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                                 PROMISSORY NOTE

                            (Facility B Advance Note)

$15,000,000.00                    Dallas, Texas                February 9, 1996


         QUEST MEDICAL, INC., a Texas corporation, with its principal office
located at One Allentown Parkway, Allen, Texas 75002 ("Borrower"), for value
received, promises to pay to the order of NATIONSBANK OF TEXAS, N.A. ("Lender"),
at its Dallas Banking Center at 901 Main Street, Dallas, Texas 75202, in
immediately available funds and in lawful money of the United States of America,
the principal sum of Fifteen Million and 00/100 Dollars ($15,000,000.00), or
such lesser sum as shall be due and payable from time to time hereunder, on
December 31, 1997, or sooner, as provided in the Credit Agreement referred to
below. Borrower promises to pay interest on the unpaid principal amount of the
Facility B Advances (as defined in the Credit Agreement) from the date made
until such principal amount is paid in full, at such interest rates, and payable
at such times, as are specified in the Credit Agreement.

         For the purposes of this Note, the following terms have the respective
meanings assigned to them below:

                  "Applicable Law" means the laws of the United States of
         America applicable to contracts made or performed in the State of
         Texas, including, without limitation, 12 USC 86, as amended to the date
         hereof and as the same may be amended at any time and from time to time
         hereafter and any other statute of the United States of America now or
         at any time hereafter prescribing maximum rates of interest on loans
         and extensions of credit, and the laws of the State of Texas,
         including, without limitation, Article 1.04, Title 79, Revised Civil
         Statutes of Texas, 1925, as the same may be amended at any time and
         from time to time hereafter ("Article 1.04") and any other statute of
         the State of Texas now or at any time hereafter prescribing maximum
         rates of interest on loans and extensions of credit provided that
         pursuant to Article 5069-15.10(b), Title 79, Revised Civil Statues,
         1925, as amended, Borrower agrees that the provisions of Chapter 15,
         Title 79, Revised Civil Statutes of Texas, 1925, as amended, shall not
         apply to this Note.

                  "Highest Lawful Rate" means at the particular time in question
         the maximum rate of interest which, under Applicable Law, Lender is
         then permitted to charge on the obligation hereunder. If the maximum
         rate of interest which, under Applicable Law, Lender is permitted to
         charge on the obligation hereunder shall change after the date hereof,
         the Highest Lawful Rate shall be automatically increased or decreased,
         as the case may be, from time to time as of the effective time of each
         change in the Highest Lawful Rate without notice to Borrower. For
         purposes of determining the Highest Lawful Rate under the Applicable
         Law of the State of Texas, the applicable rate ceiling shall be (i) the
         indicated rate ceiling described in and computed in accordance with the
         provisions of Section (a)(1) of Article 1.04, Title 79, Revised Civil
         Statues of Texas 1925, as amended, or (ii) if the parties subsequently
         contract as allowed by Applicable Law, the quarterly 
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         ceiling or the annualized ceiling computed pursuant to Section (d) of
         said Article 1.04; provided, however, that if at any time the indicated
         rate ceiling, the quarterly ceiling or the annualized ceiling, as
         applicable, shall be less than 18% per annum or more than 24% per
         annum, the provisions of Sections (b)(1) and (2) of said Article 1.04
         shall control for purposes of such determination, as applicable.

         Notwithstanding the foregoing and all other provisions of this Note and
any documents and instruments executed in connection with this Note, in no event
shall the interest payable hereon, whether before or after maturity, exceed the
Highest Lawful Rate of interest which, under Applicable Law, Lender is permitted
to charge to Borrower.

         All agreements between Borrower and Lender, or any subsequent holder of
this Note, whether now existing or hereafter arising and whether written or
oral, are expressly limited so that in no contingency or event whatsoever,
whether by reason of acceleration of the maturity of this Note or otherwise,
shall the amount paid or agreed to be paid to the holder of this Note for the
use, forbearance, or detention of the funds advanced pursuant to this Note or
for the performance or payment of any covenant or obligation contained herein or
in any other document evidencing, securing or pertaining to this Note, exceed
the maximum amount permissible under Applicable Law. If from any circumstance
whatsoever fulfillment of any provision hereof or of any such other document, at
the time performance of such provision shall be due, shall involve transcending
the limit of validity prescribed by Applicable Law, then ipso facto, the
obligation to be fulfilled shall be reduced to the limit of such validity, and
if from any circumstance the holder hereof shall ever receive anything of value
deemed excess interest by Applicable Law, an amount equal to any such excess
interest shall be applied to the reduction of the principal amount owing under
this Note, and not to the payment of interest, or if such excess interest
exceeds the unpaid principal balance of this Note, such excess interest shall be
refunded to Borrower. All sums paid or agreed to be paid to any holder of this
Note for the use, forbearance or detention of any funds advanced pursuant to
this Note shall, to the extent permitted by Applicable Law, be amortized,
prorated, allocated and spread throughout the full term of this Note until
payment in full so that the rate of interest on account of the indebtedness
evidenced by this Note is uniform throughout the term hereof. The terms and
provisions of this paragraph shall control and supersede every other provision
of all agreements between Borrower and any holder of this Note.

         This Note is issued pursuant to the Second Amended and Restated Credit
Agreement between Borrower and Lender dated as of February 9, 1996 (such
agreement, together with all amendments and restatements, the "Credit
Agreement"), to which reference is made for a statement of the rights and
obligations of Lender and the duties and obligations of Borrower in relation
thereto; but neither this reference to the Credit Agreement nor any provision
thereof shall affect or impair the absolute and unconditional obligation of
Borrower to pay unpaid principal of and interest on this Note when due. The
Credit Agreement among other things, contains provisions for acceleration of the
maturity hereof upon the happening of certain stated events and also for
prepayments on account of principal hereof prior to the maturity hereof upon the
terms and conditions therein specified. If a breach of or default under the
Credit Agreement 


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or any other Loan Paper (as defined in the Credit Agreement) shall occur, unpaid
principal of and interest on this Note may be declared due and payable without
notice, at the option of the holder of this Note, in the manner and with the
effect provided thereunder. Failure to exercise this option shall not constitute
a waiver of the right to exercise the same in the event of any subsequent
default or event of default. This Note is a renewal and restatement of the
promissory note (Facility B Note) dated March 31, 1995 made by Borrower and
payable to the order of Lender in the principal amount of $15,000,000.00, and is
not a novation or impairment of such note.

         If this Note is placed in the hands of an attorney for collection after
default, or if all or any part of the indebtedness represented hereby is proved,
established or collected in any court or in any bankruptcy, receivership, debtor
relief, probate or other court proceedings, Borrower and all endorsers, sureties
and guarantors of this Note jointly and severally agree to pay reasonable
attorneys' fees and collection costs to the holder hereof in addition to the
principal and interest payable hereunder.

         Borrower and all endorsers, sureties and guarantors of this Note hereby
severally waive demand, presentment for payment, protest, notice of protest,
notice of acceleration of and notice of intention to accelerate the maturity of
this Note, diligence in collecting, the bringing of any suit against any party
and any notice of or defense on account of any extensions, renewals, partial
payments or changes in any manner of or in this Note or in any of its terms,
provisions and covenants, or any releases or substitutions of any security, or
any delay, indulgence or other act of any trustee or any holder hereof, whether
before or after maturity.

         THIS NOTE AND THE RIGHTS AND DUTIES OF THE PARTIES HEREUNDER SHALL BE
GOVERNED BY THE LAWS OF THE STATE OF TEXAS, EXCEPT TO THE EXTENT THE SAME ARE
GOVERNED BY THE FEDERAL LAWS OF THE UNITED STATES OF AMERICA APPLICABLE TO
NATIONAL BANKS. THE BOOKS AND RECORDS OF LENDER SHALL CONSTITUTE PRIMA FACIE
EVIDENCE OF ALL SUMS DUE LENDER HEREUNDER.

                                  QUEST MEDICAL, INC.

                                  By:
                                     ------------------------------------------
                                  F. Robert Merrill III, Vice President


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               N O T I C E   O F   F I N A L   A G R E E M E N T
               -------------------------------------------------


THIS NOTE AND THE OTHER WRITTEN LOAN PAPERS EXECUTED CONTEMPORANEOUSLY WITH THIS
NOTE 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.

BORROWER REPRESENTS THAT IT TODAY RECEIVED A COPY OF THIS NOTICE.

Borrower                               Lender

QUEST MEDICAL, INC.                    NATIONSBANK OF TEXAS, N.A.

By:                                    By:
   --------------------------             ------------------------------
   F. Robert Merrill III,                 Brian K. Schneider,
   Vice President                         Senior Vice President

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