[Letterhead of Ontario Municipal Employees Retirement Board]


                                                                December 8, 1995

Myo Diagnostics, Inc.
3710 South Robertson Blvd., Suite 212
Culver City, California 90232
Attn: Mr. Gerald D. Appel

    Re:  Waiver of Rights
         ----------------

Ladies and Gentlemen:

    Reference is made to (1) that certain Securities Purchase Agreement, dated
as of December 23, 1994 (the "First Purchase Agreement"), by and among Myo
Diagnostics, Inc. (the "Company"), Ontario Municipal Employees Retirement Board
("OMERB"), Gerald D. Appel and Hershel Toomim and (2) that certain Securities
Purchase Agreement, dated as of August 18, 1995 (the "Second Purchase
Agreement"), by and among the Company, OMERB and Gerald D. Appel OMERB is the
Holder of 100% of the Registrable Securities (as deemed in the First and Second
Purchase Agreements).

    OMERB understands that the Company wishes to sell and issue not less than
300,000 nor more than 750,000 shares of cumulative convertible redeemable
preferred stock at a purchase price of $5.00 per share (the "Proposed
Offering"), such convertible preferred stock (the "Preferred Stock") to have the
rights and preferences described in that certain Confidential Offering
Memorandum of the Company dated as of December 8, 1995 a copy of which is
attached hereto as Exhibit A (the "Memorandum"). In connection with the Proposed
Offering, the Company has requested OMERB to waive its rights of first refusal
under Section 9.01 of the First Purchase Agreement and Section 9.01 of the
Second Purchase Agreement and to waive compliance by the Company with certain
covenants contained in the First Purchase Agreement and the Second Purchase
Agreement in connection with the Proposed Offering.

    Accordingly, pursuant to Section 10.02 of the First Purchase Agreement and
Section 10.02 of the Second Purchase Agreement, the undersigned hereby (1)
waives its rights of first refusal set forth in Section 9.01 of the First
Purchase Agreement and Section 9.01, of the Second Purchase Agreement in
connection with the sale and issuance by the Company of not less titan 300,000
shares nor more than 750,000 shares of Preferred Stock in accordance with the
terms of the Proposed Offering; (2) waives its rights under Section 9.01(b) of
the First Purchase Agreement and Section 9.01(b) of the Second Purchase
Agreement to notice of the Proposed Offering, any subsequent conversion of the
Preferred Stock into Common Stock or any subsequent exercise of any warrants
issuable upon conversion of the Preferred Stock; (3) waives compliance by the
Company with the



provisions of Sections 7.02(a), 7.02(b), and 7.02(c) of the First Purchase
Agreement and Sections 7.02(a), 7.02(b) and 7.02(c) of the Second Purchase
Agreement insofar as required to permit the consummation of the sale and
issuance of the Preferred Stock pursuant to the Proposed Offering, the
subsequent conversion of the Preferred Stock Into Common Stock, the payment of
cumulative annual dividends on the Preferred Stock at the rate of $.50 per
share, and the performance by the Company of the other covenants and agreements
in the terms of the Preferred Stock described in the Memorandum; and (4) waives
compliance by the Company with the provisions of Section 7.02(k) of the First
Purchase Agreement and Section 7.02(k) of the Second Purchase Agreement insofar
as the terms of the Preferred Stock described in the Memorandum may be deemed to
be "affirmative or negative covenants more favorable to an equity investor in
the Company" than those contained in the two Purchase Agreements.

    This waiver is conditioned upon the consummation of the Proposed Offering
on or before August 13, 1996 and in the event that the Proposed Offering is not
consummated on or before such date, this waiver shall be of no further force of
effect.

ONTARIO MUNICIPAL EMPLOYEES RETIREMENT BOARD



By:  /s/ Peter D. Friend
   -------------------------------------
   Peter D. Friend
   Portfolio Manager


By:  /s/ Henry A. Rachfalowski
   -------------------------------------
   Henry A. Rachfalowski
   Vice President


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