<PAGE>
 
                                                                  
                                                               Exhibit 2.2     
 
                AMENDMENT NO. 1 TO AGREEMENT AND PLAN OF MERGER
                 AND AMENDMENT NO. 1 TO REVOLVING CREDIT LINE
                         AND REVOLVING PROMISSORY NOTE
   
  This Amendment No. 1 to the Agreement and Plan of Merger and Amendment No. 1
to Revolving Credit Line and Revolving Promissory Note dated as of October 1,
1998 (the "Merger Agreement") is entered into this 16th day of March, 1999, by
and among Autonomous Technologies Corporation ("Autonomous"), Summit
Technology, Inc. ("Summit") and Alpine Acquisition Corp. ("Alpine").
Capitalized terms used herein and not otherwise defined shall have the same
meaning as in the Merger Agreement.     
 
  WHEREAS, pursuant to notice duly given on February 17, 1999, Summit extended
the termination date of the Merger Agreement to March 30, 1999 and agreed to
increase the line of credit to Autonomous under the revolving credit line to
$6.5 million; and
 
  WHEREAS, the parties now desire to, among other things, extend the
termination date of the Merger Agreement to April 30, 1999.
 
  NOW THEREFORE, pursuant to Section 8.4 of the Merger Agreement, the parties
hereby agree to amend the Merger Agreement as follows:
 
  1. Article VII of the Merger Agreement shall be amended by replacing the
     reference to February 28, 1999 with April 30, 1999.
 
  2. The last paragraph of Section 7.1 shall be deleted in its entirety.
 
  3. In connection with the execution of this Amendment, Summit and
     Autonomous hereby amend the Revolving Credit Line letter agreement,
     dated October 1, 1998, such that all references to $5,000,000 within
     such Revolving Credit Line letter are hereby replaced with $8,000,000.
     Further, Summit and Autonomous hereby amend the Revolving Promissory
     Note made by Autonomous to Summit, dated October 1, 1998, such that the
     reference to "Five Million Dollars ($5,000,000)" in the first paragraph
     of that Note is hereby replaced with "Eight Million Dollars
     ($8,000,000)."
 
  4. A new Section 1.6(g) shall be inserted into the Merger Agreement as
     follows:
 
    (g) Assumption of Warrants. At the Effective Time, each warrant to
        purchase Company Common Stock (a "Warrant") shall represent the
        right to purchase and receive (in lieu of the Company Stock
        purchasable and receivable upon exercise of the rights represented
        thereby), upon exercise of the Warrant, the Merger Consideration
        issued or payable with respect to or in exchange for a number of
        outstanding shares of Company Common Stock equal to the number of
        shares of Company Common Stock purchasable and receivable upon the
        exercise of such Warrant immediately before the Merger. The
        provisions of each Warrant (including, without limitation,
        provisions for adjustment of the exercise price and the number of
        shares purchasable and receivable upon exercise of the Warrant)
        shall be applicable, as nearly as practicable, after the Merger in
        relation to the Merger Consideration deliverable upon exercise of
        the Warrant. At or before the Effective Time, Summit shall execute
        such instruments of assumption as may be required by any Warrant.
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  5. Section 5.11 of the Merger Agreement is hereby amended in its entirety
     such that it reads as follows:
 
           "Upon reasonable notice from the other, Parent and the Company
           shall use their respective best efforts to cause Deloitte & Touche
           LLP, as auditor of the December 31, 1998 financial statements for
           each of the Parent and the Company, and the Company shall use its
           best efforts to cause Arthur Andersen LLP, as auditor of its
           December 31, 1996 and 1997 financial statements, to deliver to
           Parent or the Company, as the case may be, a letter, dated within 2
           business days of the Effective Date of the S-4 Registration
           Statement covering such matters as are requested by Parent or the
           Company and as are customarily addressed in accountant's "comfort"
           letters."
 
  6. This Amendment may be executed in two or more counterparts, each of
     which shall be deemed an original but all of which together shall
     constitute one and the same instrument. This
     Amendment may be executed by facsimile signature.
 
  7. Except as amended hereby, the Merger Agreement the Revolving Credit Line
     letter agreement and the Revolving Promissory Note shall remain in full
     force and effect in accordance with their terms.
 
  IN WITNESS WHEREOF, the parties have executed this Amendment as of the date
first written above.
 
                                        SUMMIT TECHNOLOGY, INC.
                                                
                                             /s/ Robert J. Palmisano     
                                        By:____________________________________
                                           Name:
                                           Title:
 
                                        ALPINE ACQUISITION CORP.
                                                
                                             /s/ Robert J. Palmisano     
                                        By: ___________________________________
                                           Name:
                                           Title:
 
                                        AUTONOMOUS TECHNOLOGIES CORPORATION
 
                                                  /s/ Randy W. Frey
                                        By: ___________________________________
                                           Name: Randy W. Frey
                                           Title:CEO