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                                                                    EXHIBIT 10.4

                                  AMENDMENT TO
                              EMPLOYMENT AGREEMENT
                              --------------------

         This Amendment to Employment Agreement is hereby entered into by and
between Opticon Medical, Inc., an Iowa corporation (the "Company") and William
J. Post, an individual resident of the State of Ohio (the "Executive") as of the
12th day of February, 1998.

         Whereas, the Company and Executive are parties to an Employment
Agreement, dated as of March 10, 1997, by and between the Company and the
Executive (the "Employment Agreement"), which the parties now desire to amend;

         Whereas, pursuant to Section 4.02 of the Employment Agreement,
Executive is eligible for a cash bonus of $60,000 payable in two equal
installments on September 10, 1997 and March 10, 1998 upon the achievement of
milestones set by the Company's Board of Directors;

         Whereas, the Company acknowledges that the milestones underlying such
bonus have been met and that the Executive has earned the bonus in accordance
with the Employment Agreement;

         Whereas, the Company was unable to pay Executive the first installment
of the bonus on September 10, 1997 because of the Company's limited financial
resources, and it is unlikely that the Company will be able to pay Executive the
second bonus installment on March 10, 1998;

         Whereas, Executive and the Company desire to amend the Employment
Agreement to provide that interest shall accrue on the unpaid bonus payments and
to provide for the conversion of the unpaid bonus payments and interest accrued
thereon into equity in the Company;

         NOW THEREFORE, in consideration of the mutual promises contained
herein, Company and the Executive agree to amend the Employment Agreement as
follows:

         1. The Employment Agreement is hereby amended by the addition of the
following sentence at the end of Section 4.02:

                  The bonus payments due and payable to Executive on September
                  10, 1997 and March 10, 1998 shall not be paid to Executive
                  until January 31, 1999, and shall accrue interest at the
                  annual rate of ten (10) percent from the respective due date
                  of each bonus payment until January 31, 1999, the date the
                  bonus payments and all accrued interest thereon shall be due
                  and payable.

         2. The Employment Agreement is hereby amended by the addition of the
following as Section 4.07:



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                  4.07 CONVERSION OF BONUS. Notwithstanding any other provision
                  in this Agreement to the contrary, upon the Company's sale
                  during calendar year 1998 of at least $2,000,000 aggregate of
                  its Common Stock, Convertible Preferred Stock, Series A, or a
                  new series of preferred stock established by the Company (the
                  "1998 Offering"), the amount of unpaid bonus payments and
                  accrued interest to date thereon shall be converted into
                  Common Stock of the Company. The unpaid bonus amount and
                  accrued interest shall be converted into the number of shares
                  of bonus amount and accrued interest being converted into the
                  number of shares of the Company's Common Stock equal to the
                  unpaid bonus payments and accrued interest being converted,
                  less the amount required to be withheld by the Company for
                  federal and state taxes, divided by the lesser of (i) the per
                  share price paid for the securities in the 1998 Offering or
                  (ii) $1.50 (the "Conversion Price"); provided, however if the
                  1998 Offering is an offering of the Company's Convertible
                  Preferred Stock, Series A, or a new series of preferred stock
                  established by the Company and the per share price paid in
                  such offering is $1.50 or less, then the unpaid bonus amount
                  and accrued interest thereon, less the amount required to be
                  withheld by the Company for federal and state taxes, shall be
                  converted into the preferred stock offered in the 1998
                  Offering in lieu of the Company's Common Stock. In addition,
                  concurrently with the conversion of the unpaid bonus payments
                  and accrued interest into stock of the Company, the Company
                  shall issue a warrant to Executive exercisable for ten (10)
                  years from the date of issue for that number of shares of
                  Common Stock of the Company equal to the number of shares of
                  Company stock, either common or preferred, into which the
                  unpaid bonus amount and accrued interest is converted pursuant
                  to this section. The exercise price for the warrant shares
                  shall be equal to the Conversion Price. The warrant shall be
                  in substantially the same form as the Series 1998 Warrants to
                  be issued by the Company pursuant to the terms of the Series
                  1998 Convertible Debentures issued by the Company, which form
                  is attached hereto as an exhibit.

         3. All other provisions of the Employment Agreement shall remain in
full force and effect and shall not be modified by this Amendment.



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         IN WITNESS WHEREOF, the Executive and the Company have executed this
Amendment as of the date first written above.

                                            OPTICON MEDICAL INC.



                                            By /s/ Walter L. Sembrowich
                                               ---------------------------------
                                               Walter L. Sembrowich,
                                               Chairman of the Board


                                            WILLIAM J. POST

                                                /s/ William J. Post
                                                --------------------------------


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