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                                     EXHIBIT 10.1

                           VISTA MEDICAL TECHNOLOGIES, INC.
                               THIRD AMENDMENT TO LEASE
                           --------------------------------

    This Third Amendment to Lease (the "Amendment") is made as of this 1st 
day of September, 1997, by and between Robert F. Tambone, as Trustee of MAT 
Realty Trust, u/d/t dated June 4, 1986 and recorded with the Worcester County 
Registry of Deeds in Book 9569, Page 286 (the "Landlord") and VISTA Medical 
Technologies, Inc., a Delaware corporation, successor in interest to OKTAS, a 
Massachusetts general partnership of which OKTAS, Inc., a Massachusetts 
corporation and VISTA Medical Technologies, Inc., a California corporation 
were the sole general partners (the "Tenant").

    Reference is hereby made to a certain lease (as amended, the "Lease") 
dated as of April 14, 1994 by and between Landlord and Tenant; a certain 
First Amendment to Lease dated as of March 1, 1996 (the "First Amendment"), 
and a certain Second Amendment to Lease dated as of October 28, 1996 (the 
"Second Amendment"), relating to certain space in the building located at 134 
Flanders Road, Westborough, Massachusetts.  The Guaranty of Kaiser Aerospace 
and Electronics Corporation, a Nevada corporation, remains with respect to 
the obligations arising from the 8,733 square feet originally leased under 
the Lease (the "Original Premises"), and the obligations of Tenant under the 
First Amendment are secured by a security deposit in lieu of a guaranty.  
Capitalized terms used herein and not otherwise defined shall have the 
meanings set forth in the Lease.

    WHEREAS, Landlord and Tenant desire to add 4,454 rentable square feet of 
space on the first floor of the Building (the "Third Amendment Additional 
Premises") to the Premises leased under the Lease, the First Amendment, and 
the Second Amendment, and to amend the Lease in the manner hereinafter 
provided;

    NOW, THEREFORE, in consideration of the agreements set forth herein and 
for other good and valuable consideration, the receipt and sufficiency of 
which is hereby acknowledged, Landlord and Tenant hereby amend the Lease as 
of September 1, 1997 (the "Effective Date") as follows:     

    1.   In addition to the Base Rent described in  Section 1.1 of the Lease, 
and in addition to the Base Rent described in the First Amendment, and Second 
Amendment, the following is inserted therewith and added thereto:

    "Third Amendment Additional Premises Base Rent:  The sums set forth 
below, as the same may be adjusted and/or abated pursuant to this Lease:

    (a)  Forty Eight Thousand Nine Hundred Ninety Four Dollars ($48,994.00)
         annually ($4,082.83 monthly) for the first year of the Term, i.e.
         through August 31, 1998 ($11.00 per square foot of Premises Rentable
         Area).


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    (b)  Fifty One Thousand Two Hundred Twenty One Dollars ($51,221.00)
         annually ($4,268.42 monthly) for the second year of the Term, i.e.
         through August 31, 1999 ($11.50 per square foot of the Premises
         Rentable Area).

    (c)  Fifty Three Thousand Four Hundred Forty Eight Dollars ($53,448.00)
         annually ($4,454.00 monthly) for the third and fourth years of the
         Term and through the expiration of the Term, i.e. through October 31,
         2001 ($12.00 per square foot of the Premises Rentable Area).

         The Base Rent for the Third Amendment Additional Premises shall
         commence to be due and payable on the Effective Date."

    2.   The definition of "Premises" contained in Section 1.1 of the Lease 
is hereby deleted and the following is inserted therefor:
    
         "22,524 square fee until the Effective Date and, then, 26,978 square
         feet (the "Premises Rentable Area") of the Building which is agreed to
         be as shown on EXHIBIT FP annexed hereto."

    3.   The definition of "Tenant's Proportionate Share" contained in 
Section 1.1 of the Lease is hereby deleted and the following is inserted 
therefor:

         "The quotient derived by dividing the Premises Rentable Area by the
         Building Rentable Area which as of the execution date of this Lease
         Amendment is 39.52% and, as of the Effective Date, will become
         47.33%."

    4.   EXHIBIT FP of the Lease is hereby deleted and the plan attached 
hereto as EXHIBIT FP is hereby incorporated into the Lease as EXHIBIT FP. 

    5.   The Term for the Third Amendment Additional Premises shall extend 
from the Effective Date through October 31, 2001.  The Term for the Original 
Premises and the Additional Premises leased pursuant to the Lease, the First 
Amendment, and the Second Amendment, shall be unchanged by this Third 
Amendment.

    6.   Except as otherwise expressly stated herein, the Additional Premises 
shall be delivered to Tenant by Landlord in its "AS IS" condition on the 
Effective Date and thereupon shall become part of the Premises.  Landlord 
shall not be obligated to install any tenant improvements.  Any work done by 
Tenant in the Additional Premises shall be done in full compliance with all 
applicable laws and regulations, with Section 5.2 of the Lease, and with all 
other applicable provisions of the Lease.

    7.   Landlord and Tenant agree that Tenant shall be obligated to pay, in 
the manner specified in Section 8.2 of the Lease, a management fee of three 
(3%) percent of Base Rent 


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relative to the Premises, the Additional Premises, the Second Amendment 
Additional Premises, and the Third Amendment Additional Premises.

    Except as expressly set forth herein, the Lease shall remain unmodified 
and in full force and effect.

    IN WITNESS WHEREOF, Landlord and Tenant have caused this Amendment to be 
duly executed, under seal, by persons hereunto duly authorized, in multiple 
copies, each to be considered an original hereof, as of the date first set 
forth above.

                                   LANDLORD:



                                      /s/ ROBERT F. TAMBONE, TRUSTEE   
                                    --------------------------------------
                                    Robert F. Tambone, Trustee as
                                    aforesaid and not individually


                                    TENANT:

                                    VISTA MEDICAL TECHNOLOGIES, INC., a
                                    Delaware corporation


                                    By:   /s/ JOHN LYON                    
                                        ------------------------------------
                                    Name:   John Lyon        
                                    Title:  President               
                      

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