<PAGE>

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                   FORM 10-K/A

              X        ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d)

              OF THE SECURITIES EXCHANGE ACT OF 1934 (FEE REQUIRED)

                     For fiscal year ended December 31, 1998

                                       OR

      TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES
                     EXCHANGE ACT OF 1934 (NO FEE REQUIRED)

               For the transition period from ________ to _______.

                         Commission File Number: 0-22743

                        VISTA MEDICAL TECHNOLOGIES, INC.
             (Exact name of Registrant as specified in its charter)

              DELAWARE                                      94-3184035
  (State or other jurisdiction of                        (I.R.S. Employer
   incorporation or organization)                        Identification No.)

                            5451 Avenida Encinas,
                      Suite A, Carlsbad, California 92008
                    (Address of principal executive offices)
                                 (760) 603-9120
              (Registrant's telephone number, including area code)

        Securities registered pursuant to Section 12(b) of the Act: None

 Securities registered pursuant to Section 12(g) of the Act: Common Stock, par
                              value $.01 per share

         Indicate by check mark whether the registrant (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___

         Indicate by check mark if disclosure of delinquent filers pursuant to
Item 405 of Regulation S-K is not contained herein, and will not be contained,
to the best of registrant's knowledge, in definitive proxy or information
statements incorporated by reference in Part III of this Form 10-K or any
amendment to this Form 10-K. [ ]

         The aggregate market value of the voting stock held by nonaffiliates of
the registrant as of January 31, 1999 was approximately $16,553,000. For the
purposes of this calculation, shares owned by officers, directors and 10%
stockholders known to the registrant have been deemed to be owned by affiliates.
This determination of affiliate status is not necessarily a conclusive
determination for other purposes.

         The number of shares outstanding of the registrant's Common Stock as of
March 25, 1999 was 13,673,876.

         Portions of Registrant's Proxy Statement for the Annual Meeting of
Stockholders scheduled to be held on June 8, 1999, to be filed on or about April
28, 1999 and referred to herein as the "Proxy Statement", are incorporated as
provided in Part III.

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         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.

                                            VISTA MEDICAL TECHNOLOGIES, INC.

         Date:  September 7, 1999           By:  /s/ John R. Lyon
                                               ---------------------------------
                                               John R. Lyon
                                               President and Chief Executive
                                               Officer

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

<TABLE>
<CAPTION>
    SIGNATURE                     TITLE                                  DATE
    ---------                     -----                                  ----
<S>                          <C>                                     <C>
/s/  John R. Lyon            President, Chief Executive               September 7, 1999
--------------------------    Officer and Director (Principal
    (John R. Lyon)            Executive Officer)

/s/  Robert J. De Vaere*     Vice President of Finance and            September 7, 1999
--------------------------    Administration and Chief
    (Robert J. De Vaere)      Financial Officer (Principal
                              Financial and Accounting Officer)

/s/  James C. Blair*         Chairman of the Board and Director       September 7, 1999
--------------------------
    (James C. Blair)

/s/  Olav B. Bergheim*       Director                                 September 7, 1999
--------------------------
    (Olav B. Bergheim)

/s/  Nicholas B. Binkley*    Director                                 September 7, 1999
--------------------------
    (Nicholas B. Binkley)

/s/  Daniel J. Holland*      Director                                 September 7, 1999
--------------------------
    (Daniel J. Holland)

/s/  Larry M. Osterink*      Director                                 September 7, 1999
--------------------------
    (Larry M. Osterink)
</TABLE>

*By:  /s/     John R. Lyon         September 7, 1999
      --------------------------
            Attorney-in-fact


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(c)      Exhibits

<TABLE>
<CAPTION>
  NUMBER
  EXHIBIT               DESCRIPTION
----------              -----------
<S>                 <C>
 (1)     10.1       Amended and Restated Sales Agreement between the Company and
                    Medtronic, Inc., dated June 26, 1998 (with certain
                    confidential portions omitted).

 (2)     10.2       Vista Medical Technologies, Inc., Industrial Real Estate
                    Lease between the Company and Ocean Point Tech Centre dated
                    July 7,1998.

 +*      10.3       Amendment Number One to License Agreement between the
                    Company and Imagyn Medical Technologies, Inc., dated
                    October 2, 1998.

         10.4       Employment Agreement with John Lyon dated December 28,
                    1998

         10.5       Employment Agreement with Koichiro Hori dated December 28,
                    1998

         10.6       Employment Agreement with Allen Newman dated December 28,
                    1998

         10.7       Employment Agreement with Robert De Vaere dated
                    December 28, 1998

  +      23.1       Consent of Ernst & Young LLP, Independent Auditors.

  +      24.1       Power of Attorney.

  +      27.1       Financial Data Schedule.
</TABLE>

        * Certain confidential portions of this Exhibit were omitted by means of
        redacting a portion of the text (the "Mark"). This Exhibit has been
        filed separately with the Secretary of the Commission without the Mark
        pursuant to the Company's Application Requesting Confidential Treatment
        under Rule 406 under the Securities Act.

        (1) Incorporated by reference to the Company's Form 10-Q, filed on
        August 12, 1998.

        (2) Incorporated by reference to the Company's Form 10-Q, filed on
        November 13, 1998.

        + Previously filed.

SUPPLEMENTAL INFORMATION

         Copies of the Registrant's Proxy Statement for the Annual Meeting of
Stockholders to be held June 8, 1999 and copies of the form of proxy to be used
for such Annual Meeting were furnished to the Commission prior to the time they
were distributed to the Stockholders.

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