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                                                                    EXHIBIT 4.3

                              SECOND AMENDMENT TO
               AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT

                  This Second Amendment to Amended and Restated Registration
Rights Agreement (the "Amendment") amends that certain Amended and Restated
Registration Rights Agreement dated as of October 21, 1996, as amended pursuant
to that certain First Amendment to Amended and Restated Registration Rights
Agreement dated November 30, 1999, (the "Agreement") by and among SPECTRX,
INC., a Delaware corporation (the "Company") and the holders of Registrable
Securities (as such term is defined in the Agreement).

                              W I T N E S S E T H:

                  WHEREAS, the Company has determined to issue and sell to
George F. Landegger, a resident of the State of Connecticut, The Whittemore
Collection, Ltd., a corporation and T. Brown Badgett, a resident of the State
of Kentucky (collectively, the "Purchasers", and individually each a
"Purchaser") a total of 500,000 shares of common stock, par value $.001 per
share, of the Company ("Common Stock"), and as a condition to the obligation of
Purchasers to purchase shares of Company Stock, the Company and Purchasers
desire to effect an amendment to the Agreement to provide Purchasers with
registration rights in respect of shares of Common Stock to be issued to
Purchasers by the Company;

                  WHEREAS, the holders of at least a majority of the
Registrable Securities for the benefit of the Company have agreed, to induce
Purchasers to purchase the 500,000 shares of Common Stock referenced above, to
amend the Agreement by entering into this Amendment;

                  NOW, THEREFORE, in consideration of the mutual promises and
other terms and conditions set forth in the Agreement and in the agreements
pursuant to which Purchasers will acquire the Common Stock referenced above,
the parties hereto agree as follows:

                  1.       EFFECTIVENESS OF AMENDMENT. The Company and the
holders of Registrable Securities who have executed and delivered this
Amendment below acknowledge

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and agree that the Agreement is hereby amended by this Amendment pursuant to
the provisions of Section 14 of the Agreement whereby any provision of the
Agreement may be amended with the written consent of the Company and the
holders of a majority of the Registrable Securities then outstanding, and
further acknowledge and agree that such Amendment shall be binding upon each
holder of Registrable Securities then outstanding and each future holder of all
Registrable Securities of the Company.

                  2.       AMENDMENT. The parties hereto agree that the
definition of "Registrable Securities" as contained in Section 2 of the
Agreement is hereby amended and restated as follows:

         "Registrable Securities" shall mean (i) the Common Stock issued upon
         conversion of the Series A Preferred Stock, (ii) the Common Stock
         issued upon conversion of the Series A Preferred Stock issued upon
         exercise of certain warrants issued pursuant to the Note and Warrant
         Purchase Agreement dated April 6, 1994, (iii) the Common Stock issued
         upon conversion of the Series A Preferred Stock issued upon exercise
         of certain warrants issued pursuant to the Note and Warrant Purchase
         Agreement dated April 29, 1994, (iv) the Common Stock issued upon
         conversion of the Series A Preferred Stock issued upon exercise of
         certain warrants issued pursuant to the Note and Warrant Purchase
         Agreement dated June 15, 1994, (v) the Common Stock issued upon
         conversion of the Series B Preferred Stock, (vi) the Common Stock
         issued upon conversion of the Series C Preferred Stock, (vii) the
         Common Stock issuable or issued upon conversion of the Redeemable
         Convertible Preferred Stock, (viii) the Common Stock which may be
         issued to Abbott Laboratories pursuant to the Common Stock Purchase
         Agreement dated November 30, 1999, by and between the Company and
         Abbott Laboratories, (ix) the Common Stock which has been issued to
         George F. Landegger, The Whittemore Collection, Ltd., and T. Brown
         Badgett (the "Purchasers") pursuant to the Common Stock Purchase
         Agreement dated of even date herewith by and between the Company and
         the Purchasers and (x) any Common Stock or other securities issued
         with respect to such Series A Preferred Stock, Series B Preferred
         Stock, Series C Preferred Stock, Redeemable Convertible Preferred
         Stock or Common Stock; provided, however, that shares of Common Stock
         or other securities shall only be treated as Registrable Securities if
         and so long as they have not been (i) sold to or through a broker or
         dealer or underwriter in a public distribution or a public securities
         transaction or (ii) sold by a person in a transaction in which their
         rights under this Agreement are not assigned."

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                  IN WITNESS WHEREOF, the parties have caused this Agreement to
be duly executed and delivered by their proper and duly authorized officers as
of the date first above written.

                                    SPECTRX, INC.

                                    By:
                                       -----------------------------------------
                                    Title:
                                          --------------------------------------

                                    HILLMAN MEDICAL VENTURES 1993 L.P.,
                                      a Delaware limited partnership

                                    By:  Hillman/Dover Limited Partnership,
                                         general partner

                                    By:  Wilmington Securities, Inc.,
                                         its sole general partner

                                    By:
                                       -----------------------------------------
                                    Title:
                                          --------------------------------------

                                    NORO-MOSELEY PARTNERS II, L.P.,
                                      a Georgia limited partnership

                                    By:  Moseley & Company, II,
                                         general partner

                                    By:
                                       -----------------------------------------
                                       Jack R. Kelly, Jr.
                                    Title:  General Partner

                                    ABBOTT LABORATORIES

                                    By:
                                       -----------------------------------------
                                    Title:
                                          --------------------------------------

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                                                                    Exhibit 10.5

                                SEAN E. BELANGER

                       OUTLINE OF EMPLOYMENT RELATIONSHIP

                              PARADYNE CORPORATION

1.       Position and Responsibilities:
         a.       Position - President and Chief Operating Officer of Paradyne
                  Networks Inc.
         b.       Responsibilities - Paradyne Corporate Marketing, Worldwide
                  Sales, R&D and Product Management report directly to position.
         c.       There will likely be situations where Paradyne will acquire
                  companies and certain departments may not report into the
                  Pres/COO of Paradyne during transition periods.

2.       Compensation:
a.       Base Annual Salary:  $225,000
b.       Annual Incentive Compensation:  $125,000

3.       Equity:
         a.       Grant of 750,000 nonqualified options with:
                  (i)   Normal four year vesting
                  (iii) Option price is closing price on the day prior to the
                  grant.
         b.       Grant of 100,000 nonqualified options with:
                  (i) 60% vesting on the first anniversary and 5% each three
                  months thereafter (iii) Option price is closing price on the
                  day prior to the grant.
         Change of Control Provision:
         During the four year period covered by the grants above, Sean will have
         a Constructive Termination Clause: If there is a change of control
         (defined the same as current change of control) and Sean is not offered
         the same position at the new company then Sean's options will have 100%
         acceleration. If Sean is offered the same position at the new company
         (President and/or Chief Operating Officer) with the same
         responsibilities (Sales, Marketing and R&D) then Sean's options will
         not accelerate.

4.       Termination:
         -        By Company
         a.                With cause - Sean receives salary through date of
                           termination and is not entitled to any bonus not yet
                           paid and no further vesting beyond the termination
                           date.
         b.                Without cause - If Sean is terminated before 10/15/00
                           then Sean will receive 6 months of salary and his
                           options will vest through 4/15/01. If he is
                           terminated after 10/15/00 then Sean will receive 6
                           months of salary and 6 months vesting.
         -        By Executive
         c.                With cause - same as termination by company without
                           cause
         d.                Without cause - same as termination by company with
                           cause

5.       Noncompete Provisions: For six months after the termination of Sean, he
         will not directly or indirectly:
         1.       engage in, or be employed by, or in any way advise or act for,
                  or have any financial interest in any business which is a
                  material competitor of the company which produces, markets
                  and/or sell products or services that were offered for or
                  planned to be offered for sale, license, or lease by the
                  company while Executive was employed by the company, provided
                  however that the ownership of 1% of the outstanding securities
                  of any corporation, even though such corporation may be a
                  material competitor of the company as specified above, shall
                  not be deemed as constituting a financial interest in such
                  competitor, or
         2.       recruit, solicit, or induce or attempt to induce any employee
                  or employees of the company to terminate their employment
                  with, or otherwise cease their relationship with, the Company;
                  or
         3.       divert or take away, or attempt to divert or to take away, the
                  business or patronage for any of the clients, customers or
                  accounts, or prospective clients, customers or accounts, of
                  the Company which were contacted, solicited or served by
                  Executive while employed by the Company

Paradyne Corporation

-------------------------                         ------------------------------
Andy May, President & CEO                         Sean E. Belanger
Date: April ___, 2000                             Date: April  ___, 2000

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