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                                                                   EXHIBIT 10.81

                                SECOND AMENDMENT
                                       TO
                             O.E.M. SUPPLY AGREEMENT
                                     BETWEEN
               OLYMPUS AMERICA INC.-PRECISION INSTRUMENT DIVISION
                                       AND
                           ACCUMED INTERNATIONAL, INC.

        This is the Second Amendment ("Second Amendment") to the O.E.M. Supply
Agreement dated May 31, 1996 ("Agreement") between Olympus America
Inc.-Precision Instrument Division ("OLYMPUS") and AccuMed International, Inc.
("ACCUMED"), as initially amended on July 1, 1996. Capitalized terms used but
not otherwise defined in this Second Amendment will have the meanings ascribed
to such terms in the Agreement. The effective date of this Second Amendment is
August 31, 1997.

        OLYMPUS and ACCUMED wish to amend the Agreement. The Agreement is hereby
amended as follows:

Al.     The text of Section 7.1 of the Agreement is deleted and replaced with
        the following: THIS AGREEMENT SHALL REMAIN IN FULL FORCE AND EFFECT
        COMMENCING ON THE EFFECTIVE DATE (I.E., MAY 31, 1996) AND EXPIRING ON
        SEPTEMBER 1, 1997 (THE "AGREEMENT TERM") UNLESS EARLIER TERMINATED
        PURSUANT TO SECTION 7.2.

A2.     The text of Section 7.4 of the Agreement is deleted and replaced with
        the following: UPON EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT,
        OLYMPUS SHALL HAVE THE RIGHT, AT ITS OPTION, TO: (A) REQUIRE ACCUMED TO
        REPURCHASE FROM OLYMPUS (AT THE PRICE PAID BY OLYMPUS) SIX ACCEIL SYSTEM
        UNITS PER CALENDAR MONTH (BEGINNING IN OCTOBER 1997) UNTIL SUCH TIME AS
        OLYMPUS'S INVENTORY THEREOF IS DEPLETED, PROVIDED THAT THE SYSTEMS TO BE
        REPURCHASED ARE IN GOOD CONDITION; (B) REQUIRE ACCUMED TO PURCHASE FROM
        OLYMPUS, AT A PRICE OF $750.00 PER UNIT, THE MICROSCOPE FRAMES ATTACHED
        TO THE AFOREMENTIONED ACCEIL SYSTEM UNITS TO BE REPURCHASED BY ACCUMED;
        (C) REMOVE, OR REQUIRE ACCUMED TO REMOVE AT ACCUMED'S COST AND EXPENSE,
        ANY AND ALL AUTHORIZED TRADEMARKS FROM THE AFOREMENTIONED ACCELL SYSTEM
        UNITS TO BE REPURCHASED BY ACCUMED, PROVIDED THAT SUCH REMOVAL DOES NOT
        MATERIALLY DEFACE THE SYSTEMS; (D) CONTINUE TO SELL TO THIRD PARTIES ANY
        AND ALL 



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        PRODUCTS IN OLYMPUS'S INVENTORY; AND/OR (E) PROVIDE ONGOING SUPPORT AND
        SERVICE TO OLYMPUS'S END-USER CUSTOMERS. IN ADDITION, UPON EXPIRATION OR
        EARLIER TERMINATION OF THIS AGREEMENT, ACCUMED SHALL NOT SELL (OTHER
        THAN TO OLYMPUS) ANY PRODUCT CONTAINING OR WHICH IS PACKAGED IN
        MATERIALS CONTAINING THE AUTHORIZED TRADEMARKS AND ACCUMED SHALL
        IMMEDIATELY CEASE ANY USE OF THE AUTHORIZED TRADEMARKS. FINALLY, UPON
        EXPIRATION OR EARLIER TERMINATION OF THIS AGREEMENT, OLYMPUS WILL SELL
        TO ACCUMED, AT ACCUMED'S OPTION AND AT A PRICE EQUAL TO OLYMPUS'S COST
        OF DEVELOPMENT AND PRODUCTION, OLYMPUS'S INVENTORY OF PRODUCT
        LITERATURE, PROVIDED THAT OLYMPUS MAY REMOVE OR REQUIRE ACCUMED TO
        REMOVE, AT ACCUMED'S COST AND EXPENSE, ANY AND ALL AUTHORIZED TRADEMARKS
        FROM SUCH PRODUCT LITERATURE.

A3.     The provisions of the Agreement listed in Section 7.6 of the Agreement
        shall remain in effect and shall survive the expiration or earlier
        termination of the Agreement.

A4.     The following Sections will be added to Article 10 (Miscellaneous) of
        the Agreement:

        10.15 OLYMPUS MICROSCOPES AND ACCESSORIES. OLYMPUS AND ACCUMED WILL
        ENDEAVOR TO ENTER INTO A MUTUALLY AGREED-UPON NON-EXCLUSIVE O.E.M.
        AGREEMENT WHEREBY ACCUMED WILL PURCHASE MICROSCOPES AND RELATED
        ACCESSORIES FROM OLYMPUS. NEITHER ACCUMED NOR OLYMPUS SHALL BE LIABLE TO
        THE OTHER IF THEY CANNOT REACH AGREEMENT, FOR ANY REASON, ON A
        NON-EXCLUSIVE O.E.M. AGREEMENT.

        10.16 RELEASES. (A) "OLYMPUS RELEASED PARTIES" SHALL REFER TO OLYMPUS
        AMERICA INC. AND EACH OF ITS PRESENT AND PAST SUBSIDIARIES,
        PREDECESSORS, SUCCESSORS, LICENSEES, ASSIGNS, PARTNERSHIPS, PARENTS, AND
        AFFILIATED OR RELATED AGENTS, CORPORATIONS AND ENTITIES, AND EACH OF
        THEIR RESPECTIVE PRESENT AND PAST OFFICERS, DIRECTORS, TRUSTEES, AGENTS,
        INSURANCE CARRIERS, ATTORNEYS, PARTNERS, EMPLOYEES, AND REPRESENTATIVES.
        "ACCUMED RELEASED PARTIES" SHALL REFER TO ACCUMED INTERNATIONAL, INC.
        AND EACH OF ITS PRESENT AND PAST SUBSIDIARIES, PREDECESSORS, SUCCESSORS,
        LICENSEES, ASSIGNS, PARTNERSHIPS, PARENTS AND AFFILIATED OR RELATED
        AGENTS, CORPORATIONS AND ENTITIES, AND EACH OF THEIR RESPECTIVE PRESENT
        AND PAST OFFICERS, DIRECTORS, TRUSTEES, AGENTS, INSURANCE CARRIERS,
        ATTORNEYS, PARTNERS, EMPLOYEES, AND 



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        REPRESENTATIVES.

        (B)EXCEPT FOR (I) THE CONTINUING AND/OR SURVIVING OBLIGATIONS, COVENANTS
        AND AGREEMENTS OF THIS AGREEMENT LISTED IN SECTION 7.6 AND (II) ANY
        AMOUNTS OWED BY ACCUMED TO OLYMPUS FOR ACCUMED'S PURCHASE OF OLYMPUS
        PRODUCTS, OLYMPUS AND ITS RESPECTIVE SUCCESSORS AND ASSIGNS GENERALLY
        RELEASE AND FOREVER DISCHARGE THE ACCUMED RELEASED PARTIES, AND EACH OF
        THEM, FROM ANY AND ALL CLAIMS, CONTRACTS, DEBTS, DAMAGES, LIABILITIES,
        DEMANDS, OBLIGATIONS, COSTS, EXPENSES, DISPUTES, SUITS, ACTIONS,
        PROCEEDINGS, JUDGMENTS, EXECUTIONS, LOSSES, DUES, DEMANDS, AND CAUSES OF
        ACTION OF WHATEVER NATURE WHATSOEVER, AND ANY KIND, WHETHER KNOWN OR
        UNKNOWN, SUSPECTED OR UNSUSPECTED, FIXED OR CONTINGENT WHICH OLYMPUS NOW
        OWNS OR HOLDS OR HAS AT ANY TIME HERETOFORE OWNED OR HELD OR MAY AT ANY
        TIME OWN OR HOLD AGAINST THE ACCUMED RELEASED PARTIES, AND EACH OF THEM,
        BY REASON OF ANY ACTS, CIRCUMSTANCES, FACTS, EVENTS, TRANSACTIONS,
        MATTER, CAUSE OR THING FROM THE BEGINNING OF THE WORLD TO THE DATE
        HEREOF.

        (C) EXCEPT FOR (I) THE CONTINUING AND/OR SURVIVING OBLIGATIONS,
        COVENANTS AND AGREEMENTS OF THIS AGREEMENT LISTED IN SECTION 7.6,
        ACCUMED AND ITS RESPECTIVE SUCCESSORS AND ASSIGNS GENERALLY RELEASE AND
        FOREVER DISCHARGE THE OLYMPUS RELEASED PARTIES, AND EACH OF THEM, FROM
        ANY AND ALL CLAIMS, CONTRACTS, DEBTS, DAMAGES, LIABILITIES, DEMANDS,
        OBLIGATIONS, COSTS, EXPENSES, DISPUTES, SUITS, ACTIONS, PROCEEDINGS,
        JUDGMENTS, EXECUTIONS, LOSSES, DUES, DEMANDS, AND CAUSES OF ACTIONS OF
        WHATEVER NATURE WHATSOEVER, AND ANY KIND, WHETHER KNOWN OR UNKNOWN,
        SUSPECTED OR UNSUSPECTED, FIXED OR CONTINGENT WHICH ACCUMED NOW OWNS OR
        HOLDS OR HAS AT ANY TIME HERETOFORE OWNED OR HELD OR MAY AT ANY TIME OWN
        OR HOLD AGAINST THE OLYMPUS RELEASED PARTIES, AND EACH OF THEM, BY
        REASON OF ANY ACTS, CIRCUMSTANCES, FACTS, EVENTS, TRANSACTIONS, MATTER,
        CAUSE, OR THING FROM THE BEGINNING OF THE WORLD TO THE DATE HEREOF.

        IN WITNESS WHEREOF, the parties have caused this Second Amendment to be
        duly executed as of the date listed in the introductory paragraph
        hereof.



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            OLYMPUS AMERICA INC.                ACCUMED INTERNATIONAL, INC.
            Precision
            Instrument Division
                                                By: \s\ MICHAEL BURKE
                                                    ----------------------------
            By: SIDNEY BRAGINSKY                Name:  Michael Burke
                -------------------             Title:  President
            Name:  Sidney Braginsky
            Title:  President