<PAGE>   1
                                                                 EXHIBIT 10-A(2)

                                   ZILA, INC.

                    NON-EMPLOYEE DIRECTORS STOCK OPTION PLAN
                      (as amended through October 25, 1995)

               1. Purposes Of The Plan. The purposes of this Plan are to
enable the Company to attract and retain the best available individuals to serve
as non-employee members of the Board, to reward such directors for their
contributions to the Company, and to maximize the identity of interest between
such directors and the Company's stockholders generally.

               2. Definitions. As used herein, the following definitions shall 
apply:

                  (a) "Board" shall mean the Board of Directors of the Company.

                  (b) "Company" shall mean ZILA, INC., a Delaware corporation.

                  (c) "Exercise Price" shall mean, with respect to each Share
         granted, the Fair Market Value on the date of grant.

                  (d) "Fair Market Value" shall mean, with respect to the date a
         given Option is granted or exercised, the value determined by the Board
         in good faith using a generally accepted valuation method; provided,
         however, that where there is a public market for the Stock, the Fair
         Market Value per Share shall be the mean of the final bid and asked
         prices of the Stock on the date of grant or exercise, as reported in
         The Wall Street Journal (or, if not so reported, as otherwise reported
         by NASDAQ/National Market System or NASDAQ) or, in the event the Stock
         is listed on a stock exchange, the Fair Market Value per Share shall be
         the closing price of the Stock on such exchange on the date of grant or
         exercise of the Option, as reported in The Wall Street Journal.

                  (e) "Option" shall mean a right to purchase Stock, granted
         pursuant to the Plan.

                  (f) "Optioned Stock" shall mean the Stock subject to an
         Option.

                  (g) "Optionee" shall mean a non-employee director of the
         Company who has been granted an Option.

                  (h) "Plan" shall mean this Zila, Inc. Non-Employee Directors
         Stock Option Plan.

                  (i) "Share" shall mean a share of the Stock.

                  (j) "Stock" shall mean the common stock of the Company
         described in the Company's Certificate of Incorporation, as amended or
         restated from time to time.

                  (k) "Trading Day" shall mean a day on which the Fair Market
         Value of the Stock can be determined.

               3. Stock Subject To The Plan.

                  (a) Subject to increases and adjustments pursuant to Section 9
         hereof, the initial number of Shares reserved and available for
         distribution under the Plan shall be 200,000.

                  (b) If an Option should terminate, or be canceled, rescinded
         or surrendered, the Optioned Stock subject to such Option shall not be
         available for future grants under the Plan.
<PAGE>   2
         4.       Option Grants. An Option to purchase 2,500 Shares shall be
granted annually to each non-employee director of the Board on the date
determined pursuant to Section 10 hereof; provided, however, that such Option
shall not be granted to any non-employee director of the Company who during the
fiscal year immediately preceding such grant date (or the period that he served
as a director of the Company, if less than the full fiscal year) attended fewer
than 75 percent of the aggregate of (i) the total number of the regularly
scheduled and special meetings of the Board and (ii) the total number of
meetings held by all committees of the Board on which he served; provided,
further, that no such Options shall be granted to any of the non-employee
directors of the Company in the event that, on such grant date, the number of
Shares remaining available for distribution under the Plan is less than the
product of the number of then current non-employee directors of the Company
multiplied by 2,500.

         5.       Board Approval And Effective Dates. This Plan shall become
effective as of October 20, 1989, the date as of which the Board adopted the
Plan. The Plan shall be submitted as a proposal for stockholder approval at the
Company's 1989 Annual Meeting of Stockholders, or any adjournment thereof. In
the event that such approval is not obtained, the Board may, but need not,
terminate the Plan. The Plan and all outstanding Options shall remain in effect
until such Options shall have been exercised, shall have expired or shall
otherwise be terminated.

         6.       Term; Exercise; Rights As A Stockholder.

                  (a) The term of each Option shall be five years from the date
         of grant thereof. Subject to Section 5, an Option shall be exercisable
         upon grant and may be exercised in whole or in part at any time or
         times during its term; provided, however, that an Option may not be
         exercised for a fraction of a Share.

                  (b) An Option shall be deemed to be exercised upon receipt by
         the Company from the Optionee of written notice of such exercise. Such
         notice shall be accompanied by full payment for the Shares subject to
         such exercise.

                  (c) No person shall have any right or privilege as a
         stockholder of the Company, whether to vote or to receive dividends or
         otherwise, by reason of the grant of an Option, but shall obtain such
         right only when Shares are actually issued to such person upon the
         exercise thereof.

         7.       Payment.  The Exercise Price shall be paid:

                  (a) In United States dollars in cash or by check payable to
         the order of the Company; or

                  (b) At the election of the Optionee by delivery of Shares with
         an aggregate Fair Market Value equal to the Exercise Price; or

                  (c) By any combination of (a) and (b) above.

         The Board shall determine acceptable methods for tendering Stock as
payment upon exercise of an Option and may impose such limitations and
prohibitions on the use of Stock to exercise an Option as it deems appropriate.

         8.       Transferability Of Options. The Option may not be sold,
pledged, assigned, hypothecated, transferred, or disposed of in any manner other
than by will or by the laws of descent and distribution and may be exercised,
during the lifetime of the Optionee, only by the Optionee or by his guardian or
legal representative.

         In the event of the Optionee's death, his Option shall be exercisable,
prior to the expiration of the Option, by the person or entity to whom his
accrued and vested rights pass by will or by the laws of descent and
distribution.

                                      2
<PAGE>   3
          9. Adjustments Upon Changes In Capitalization Or Merger. If the
outstanding Stock of the Company shall at any time be changed or exchanged by
declaration of a stock dividend, split-up, combination of shares,
recapitalization, merger, consolidation, or other corporate reorganization in
which the Company is the surviving corporation, the number and kind of Shares
subject to the Plan or subject to any Options theretofore granted, and the
Options' prices, shall be appropriately and equitably adjusted.

         In the event of a liquidation or dissolution of the Company, sale of
all or substantially all of its assets, or a merger, consolidation or other
corporate reorganization in which the Company is not the surviving corporation,
or any merger or other reorganization in which the Company is the surviving
corporation but the holders of its Stock receive securities of another
corporation, any outstanding Options hereunder shall be appropriately and
equitably adjusted.

         10. Time Of Granting Options. The Option grant date shall be the third
Trading Day after the Company publicly announces its year-end financial results
for the immediately preceding fiscal year; provided, however, that grants for
the first year only under the Plan shall be effective as of the date the
Company's stockholders approve the Plan.

         11. Amendment And Termination Of The Plan. The Board may from time to
time amend the Plan in whole or part in such respects as the Board may deem
advisable or may terminate the Plan, provided, however, that amendments to the
Plan relating to the amount, price, or timing of the option grants shall not be
made more than once in any six month period. Any amendment or termination of the
Plan shall not affect Options already granted and such Options shall remain in
full force and effect as if the Plan had not been amended or terminated. Any
amendment to the Plan shall be submitted as a proposal for approval of the
Company's stockholders if such approval of the amendment is necessary for the
Plan to comply or to continue to comply with the applicable exemption, if any,
under Section 16(b) of the Securities Exchange Act of 1934, as amended, and the
rules and regulations promulgated thereunder.

         12. Conditions Upon Issuance Of Shares. The Plan, the grant, the
exercise of Options and the obligations of the Company shall be subject to all
applicable federal and state laws, rules and regulations, and to such approvals
by any regulatory or governmental agency as may be required. The Company shall
not be required to issue or deliver any certificate or certificates for Shares
of Stock prior to (i) the admission of such Shares to listing on any stock
exchange on which the Stock may then be listed, and (ii) the completion of any
registration or other qualification of such Shares under any state or federal
law (including, without limitation, the Securities Act of 1933, as amended, and
the Securities Exchange Act of 1934, as amended), or rulings or regulations of
any government body which the Company shall, in its sole discretion, determine
to be necessary or advisable.

         As a condition to the exercise of an Option, the Company may require
the Optionee to represent and warrant at the time of any such exercise that the
Shares are being purchased only for investment and without any present intention
to sell or distribute such Shares if, in the opinion of counsel for the Company,
such a representation is necessary or advisable.

         13. Option Agreement. Options shall be evidenced by written option
agreements in accordance with the terms of the Plan. A form of such agreement is
attached hereto as Exhibit "B".

         14. Miscellaneous Provisions.

             (a) Plan Expense. Any expenses of administering this Plan
         shall be borne by the Company.

             (b) Taxes. The Company shall be entitled if necessary or
         desirable to pay or withhold the amount of any tax attributable to the
         delivery of Stock under the Plan after giving the person entitled to
         receive such Stock notice as far in advance as practical, and the
         Company may defer making delivery of such Stock if any such tax may be
         pending unless and until indemnified to its satisfaction.

                                      3
<PAGE>   4
                  (c) Construction Of Plan. The validity, construction,
         interpretation, administration and effect of the Plan and of its rules
         and regulations, and rights relating to the Plan, shall be determined
         by the Board in accordance with the laws of the State of Delaware, and
         such determinations shall be final and conclusive.

                  (d) Gender. For purposes of this Plan, words used in the
         masculine gender shall include the feminine and neuter, and the
         singular shall include the plural and vice versa, as appropriate.

         As approved by the Board of Directors as of October 25, 1995.



/s/ Joseph Hines
-------------------------
JOSEPH HINES
Chairman


ATTEST:


/s/ Janice L. Backus
-------------------------
JANICE L. BACKUS
Secretary






                                      4