**NEITHER
      THIS NOTE NOR ANY SECURITIES THAT MAY BE ISSUED UPON CONVERSION HEREOF HAVE
      BEEN
      REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR REGISTERED OR
      QUALIFIED UNDER ANY STATE SECURITIES LAWS. THIS NOTE AND ANY SUCH SECURITIES
      MAY
      NOT BE TRANSFERRED UNLESS SO REGISTERED AND QUALIFIED UNDER ALL APPLICABLE
      SECURITIES LAWS, OR UNLESS SUCH REGISTRATION AND QUALIFICATION ARE NOT
      REQUIRED.**




**CONVERTIBLE
      UNSECURED PROMISSORY NOTE**




$240,000.00 August
      1,
      2006




FOR
      VALUE
      RECEIVED, the undersigned, **Solx,
      Inc.** ,
      a
      Delaware corporation (the “ Company ”),
      hereby promises to pay to **OccuLogix,
      Inc.** ,
      a
      Delaware corporation, or its assigns (“ OccuLogix ”),
      at
      the times set forth below and subject to acceleration or conversion as set
      forth
      herein, the aggregate principal amount of TWO HUNDRED AND FORTY THOUSAND DOLLARS
      ($240,000.00) (the “ Principal
      Amount ”),
      and
      interest on the unpaid Principal Amount, from time to time outstanding, which
      shall accrue on a daily basis from the date on which the Principal Amount has
      been loaned to the Company through and including the date on which such
      Principal Amount is paid in full (or the Principal Amount and accrued interest
      is converted into Conversion Shares (defined below) in accordance with Section 3 hereof),
      at an annual interest rate equal to the “Prime Rate” as announced from time to
      time by Bank of America, N.A., or its successor, plus two percent (2%). Unless
      the indebtedness evidenced by this Convertible Unsecured Promissory Note (this
      “ Note ”)
      becomes due and payable earlier as provided in Section 4 below,
      or is converted into Conversion Shares in accordance with Section 3.2 below,
      the Principal Amount then outstanding, and any interest accrued but unpaid
      thereon, shall be paid in one (1) payment in lawful money of the United States
      of America, on October 2, 2006 (the “ Maturity
      Date ”).




**1.**  Defined
      Terms .
      For
      purposes of this Note, the terms listed below shall have the respective meanings
      set forth below:




**1.1**  “ Amended
      and Restated Stockholders Agreement ”
means
      the Amended and Restated Stockholders Agreement, dated as of June 17, 2004,
      by
      and among the Company, Boston Scientific Corporation, and the stockholders
      listed on Exhibit A thereto, as such agreement may be amended, restated,
      supplemented or replaced from time to time;




**1.2**  “ business
      day ”
means
      any day that banks located in Boston, Massachusetts are open for business
      ( *i.e* .,
      not
      Saturdays, Sundays or legal holidays for such banks);




**1.3**  “ Common
      Stock ”
means
      the common stock, $.001 par value, of the Company;




**1.4**  “ Conversion
      Shares ”
means,
      in the case of any conversion pursuant to Section 3.2 below,
      shares of the Company’s Common Stock;




**1.5**  “ Due
      Diligence Period ”
means
      the time period between March 27, 2006 through and including July 31, 2006
      or
      such other date as the Company and OccuLogix may mutually agree;




**1.6**  “ Fully
      Diluted Basis ”
means
      to take into account all issued and outstanding shares of Common Stock and
      all
      issued and outstanding shares of preferred stock of the Company on an
      as-converted basis at their respective conversion prices then in
      effect;




**1.7**  “ Letter
      Agreement ”
means
      the Letter of Intent between the Company and OccuLogix dated March 26, 2006,
      as
      amended;




**1.8**  “ Material
      Adverse Effect ”
means
      any change or effect that, when taken individually or together with all other
      adverse changes or effects, is or is reasonably likely to be materially adverse
      to the business, results of operations or financial condition of the Company,
      taken as a whole;




**1.9**  “ Merger
      Agreement ”
means
      the Agreement and Plan of Merger, dated as of the date hereof, by and among
      OccuLogix, OccuLogix Mergeco, Inc., the Company and Doug P. Adams, John Sullivan
      and Peter M. Adams, acting, in each case, in his capacity as a member of the
      Stockholder Representative Committee referred to therein;




**1.10**  “ OccuLogix
      Transaction ”
means
      the merger of the Company with and into OccuLogix Mergeco, Inc. pursuant to
      the
      Merger Agreement or the acquisition of the Company by OccuLogix or any of its
      affiliates by any other means;




**1.11**  “ Original
      Promissory Note ”
means
      the Convertible Unsecured Promissory Note of the Company, dated April 4, 2006
      and in the principal amount of $2,000,000.00, issued in favor of
      OccuLogix;




**1.12**  “ Post-Conversion
      Agreement ”
has
      the
      meaning attributed to such term in Section 3.3 ;




**1.13**  “ Sale
      of the Company ”
means
      (i) during the Due Diligence Period, any agreement, agreement in principle
      or other commitment (whether or not legally binding or written or oral) relating
      to a sale of the Company in a single or related series of transactions, whether
      by merger, consolidation or other transaction (including, without limitation,
      the sale of outstanding shares of the capital stock of the Company) in which,
      in
      each case, the holders of the Company’s voting securities outstanding
      immediately prior to the consummation of the transaction or transactions own
      securities with less than a majority of the voting power of the Company or
      a
      successor immediately after the transaction (a “Change in Voting Control”), or
      by sale or license of all or substantially all of the Company’s assets, or
      otherwise (a “Competing Transaction”) or (ii) during the Due Diligence
      Period and for a three-month period following the end of the Due Diligence
      Period, the consummation of a Competing Transaction; provided, however, that
      if
      the consummation of a Competing Transaction occurs during the three-month period
      after the Due Diligence Period, then such Competing Transaction shall only
      be a
      Sale of the Company if any discussion regarding such Competing Transaction
      was
      initiated by the Company, or any step in furtherance of it was taken by the
      Company, during the Due Diligence Period. For clarification, the OccuLogix
      Transaction, if consummated, shall not be considered a Sale of the Company.
      For
      further clarification, any offering by the Company of shares of its capital
      stock in exchange for cash in which a Change of Voting Control does not occur,
      shall not be considered a Sale of the Company.




**2.**  Payment .
      Payment
      of interest and principal hereunder shall be made at the business address of
      the
      holder hereof. All computations of interest payable under this Note shall be
      made on the basis of the actual number of calendar days elapsed. All payments
      hereunder shall be applied first to any unpaid accrued interest, second to
      payment of all, if any, other amounts except principal due under or in respect
      of this Note, and third to repayment of the unpaid Principal
      Amount.




**3.**  Cancellation;
      Conversion .
      This
      Note shall be cancelled or convertible as follows:




**3.1**  Cancellation
      Upon OccuLogix Transaction .
      Notwithstanding anything else to the contrary in this Note, this Note and all
      outstanding obligations and amounts owing by the Company under this Note shall
      automatically (without any action by any party) be cancelled upon the
      consummation of the OccuLogix Transaction, unless OccuLogix should otherwise
      decide that this Note shall not be cancelled.




**3.2**  Conversion
      Upon a Sale of the Company, etc .
      At the
      sole option of OccuLogix, this Note may be converted immediately upon (with
      such
      conversion made contingent upon) (a) a
      Sale of the Company, (b) a
      breach by the Company of its exclusivity covenant in paragraph 8 of the Letter
      Agreement, (c) the
      Principal Amount remaining outstanding and owing after the Maturity Date, (d) the
      termination by OccuLogix of the Merger Agreement pursuant to Sections 8.1(b)
      or
      8.1(d) thereof, (e) the
      termination by the Company of the Merger Agreement pursuant to Section 8.1(g)
      thereof, or (f) the
      occurrence of an Event of Default as set forth in Section 4 below,
      into that number of Conversion Shares as shall be equal to 1.2% of the issued
      and outstanding capital stock of the Company on a Fully Diluted Basis. The
      Company shall give OccuLogix written notice fifteen (15) business days prior
      to
      the consummation of any Sale of the Company, which notice shall describe in
      sufficient detail the terms of such transaction, to enable OccuLogix to make
      a
      decision as to whether to exercise its option under this Section 3.2 .




**3.3**  Manner
      of Conversion .
      OccuLogix shall be deemed to be the holder of the Conversion Shares: (a) in
      connection with a conversion pursuant to Section 3.2 ,
      immediately upon (and contingent upon) the consummation of a Sale of the
      Company, provided that OccuLogix has provided the Company with written notice
      of
      conversion prior to the consummation of the Sale of the Company as provided
      in
      Section 3.2 above; (b) in
      connection with the breach by the Company of its exclusivity covenant in
      paragraph 8 of the Letter Agreement, immediately upon (and contingent upon)
      the
      independent determination of a third party arbitrator, or other competent
      decisionmaker mutually acceptable to the Company and OccuLogix, acting
      reasonably, conducted in accordance with procedures mutually acceptable to
      the
      Company and OccuLogix, acting reasonably; (c) in
      the event that the Principal Amount remains outstanding and owing after the
      Maturity Date, immediately upon (and contingent upon) the expiration of the
      cure
      period after receipt of notice as set forth in Section 4(d) below
      and provided that OccuLogix has delivered a notice to the Company of its
      intention to convert this Note pursuant to Section 3.2 ; (d) in
      connection with the termination of the Merger Agreement pursuant to Sections
      8.1(b), 8.1(d) or 8.1(g) thereof, immediately upon (and contingent upon) the
      effective time of such termination; and (e) in
      connection with an Event of Default, immediately upon (and contingent upon)
      the
      expiration of the applicable cure period after receipt of notice as set forth
      in
      Section 4 below.
      At such time, OccuLogix shall have all of the rights of a holder of Common
      Stock
      and, upon its request, shall be entitled to receive a certificate representing
      the Conversion Shares into which this Note converts. Upon conversion of the
      Principal Amount and accrued but unpaid interest on this Note into Conversion
      Shares as provided herein, the provisions of this Note relating to the
      obligation of the Company to pay principal and interest to OccuLogix, set forth
      herein, shall be null and void and no payment of principal and interest shall
      be
      owed or paid by the Company to OccuLogix pursuant to this Note. However, subject
      to the foregoing, this Note shall remain in full force and effect until such
      time as the Company and OccuLogix enter into a separate agreement that shall
      provide OccuLogix with protection substantially equivalent to the protection
      provided to OccuLogix hereunder, including, without limitation, the
      anti-dilutive protection contemplated in Section 3.4 (the
“ Post-Conversion
      Agreement ”).
      The
      Company and OccuLogix shall use best efforts to negotiate, execute and deliver
      the Post-Conversion Agreement as soon as practicable following the conversion
      of
      this Note but, in any event, by no later than the end of the 45-day period
      following the conversion of this Note, subject to any mutually agreed extension
      of time. If the Post-Conversion Agreement is not entered into within such 45-day
      period or other agreed time period, then the provisions of Section 3.4 below of
      this Note shall continue in full force and effect.




**3.4**  Continuing
      Equity Ownership .
      Until
      the earlier of (i) any merger or consolidation which results in the voting
      securities of the Company outstanding immediately prior thereto representing
      immediately thereafter (either by remaining outstanding or by being converted
      into voting securities of the surviving or acquiring entity) less than a
      majority of the combined voting power of the voting securities of the Company
      or
      such surviving or acquiring entity outstanding immediately after such merger
      or
      consolidation or any sale of all or substantially all of the assets of the
      Company, in each case, with a pre-transaction valuation of the Company equal
      to
      or greater than $5,000,000.00, and (ii) an underwritten public offering of
      shares of common stock of the Company at a pre-offering valuation of the Company
      greater than $5,000,000.00 and net proceeds to the Company of at least
      $1,000,000.00, from time to time, following the conversion of this Note pursuant
      to Section 3.2 ,
      the
      Company shall issue to OccuLogix, without payment of additional consideration
      by
      OccuLogix, such number of additional shares of Common Stock as shall be
      necessary for OccuLogix always to maintain (solely by reason of its ownership
      of
      Conversion Shares and any shares of Common Stock issued to it pursuant to this
      Section 3.4 )
      an
      ownership percentage in the Company equal to 1.2% of the issued and outstanding
      capital stock of the Company on a Fully Diluted Basis. For greater certainty,
      OccuLogix’s rights under this Section 3.4 are in
      addition to, and not in lieu of or in substitution for, any other applicable
      right that OccuLogix may have, under Section 3.4 of the Original Promissory
      Note
      and/or the Merger Agreement.




**4.**  Acceleration .
      At
      OccuLogix’s option, the entire unpaid portion of the Principal Amount and all
      accrued but unpaid interest represented by this Note will become due and payable
      upon written notice of acceleration given by OccuLogix to the Company
      immediately prior to or following any of the following (each, an “ Event
      of Default ”) (a) liquidation
      or dissolution of the Company, or any other termination or winding-up of its
      existence or business, (b) appointment
      of any receiver for the Company or its assets, (c) assignment
      by the Company for the benefit of its creditors, (d) material
      breach by the Company of this Note that is not cured within thirty (30) days’
written notice thereof from OccuLogix, in the case of any defaults other than
      payment defaults, or two (2) days’ written notice thereof from OccuLogix, in the
      case of any payment defaults, (e) institution
      by the Company of insolvency, receivership or bankruptcy proceedings or any
      other proceedings for the settlement of a party’s debts, change of control of
      the Company or Sale of the Company, or if any such proceeding shall be filed
      or
      shall be commenced against the Company by a third party and the Company shall
      indicate its approval thereof, consent thereto or acquiescence therein or such
      proceeding shall not have been dismissed within sixty (60) days following the
      filing thereof, (f) an
      event of default under any mortgage, indenture, obligation, instrument or
      indebtedness of the Company, which default results in $50,000 or more (in the
      aggregate) of such indebtedness to become due and payable by the Company prior
      to its stated maturity date (including, without limitation, an Event of Default
      (as such term is defined in the Original Promissory Note) under the Original
      Promissory Note), or (g) a
      Sale of the Company. A breach by the Company of the representation and warranty
      contained in Section 5.3 shall be
      considered a material breach of this Note.




**5.**  Representations
      and Warranties of the Company .
      The
      Company hereby represents and warrants to OccuLogix as follows:




**5.1**  Organization,
      Good Standing and Qualification .
      The
      Company is a corporation duly organized, validly existing and in good standing
      under the laws of the State of Delaware and has all requisite corporate power
      and authority to carry on its business as now conducted. The Company is duly
      qualified to transact business and is in good standing in each jurisdiction
      in
      which the failure to so qualify would have a Material Adverse Effect. The
      Company has all requisite corporate power and authority to own and operate
      its
      properties and assets, to issue this Note, the Conversion Shares and any shares
      of Common Stock issuable pursuant to Section 3.4 ,
      and to
      perform its obligations under, and carry out the provisions of, this
      Note.




**5.2**  Authorization;
      Binding Obligations; Governmental Consents .




(a)  All
      corporate action on the part of the Company, its officers, directors and
      stockholders necessary for the authorization, execution and issuance of this
      Note, and the performance of all obligations of the Company hereunder, have
      been
      taken prior to the date hereof. This Note is a valid and legally binding
      obligation of the Company, enforceable in accordance with its terms, except
      (i)
      as limited by applicable bankruptcy, insolvency, reorganization, moratorium,
      and
      other laws of general application affecting enforcement of creditors’ rights,
      and (ii) as limited by laws relating to the availability of specific
      performance, injunctive relief, or other equitable remedies.




(b)  No
      consent, approval, permit, order or authorization of, or registration,
      qualification, designation, declaration or filing with, any federal, state
      or
      local governmental authority on the part of the Company is required in
      connection with the execution and issuance of this Note.




**5.3**  Compliance
      with Other Instruments .
      The
      Company is not in violation or default of any provision of its certificate
      of
      incorporation or by-laws or similar organizational documents, or, other than
      as
      disclosed in writing to OccuLogix pursuant to the Merger Agreement, of any
      mortgage, indenture, contract, agreement, instrument, judgment, order, writ,
      decree or contract to which it is a party or by which it is bound or, to the
      best of the Company’s knowledge, of any provision of any federal or state
      statute, rule or regulation applicable to the Company, which violation or
      default could reasonably be expected to have a Material Adverse Effect. The
      issuance of this Note and the Conversion Shares will not result in any such
      violation or be in conflict with or constitute, with or without the passage
      of
      time or giving of notice, either a default under any such provision, instrument,
      judgment, order, writ, decree or material contract, or result in the creation
      of
      any mortgage, pledge, lien, charge or encumbrance upon any of the properties
      or
      assets of the Company or the suspension, revocation, impairment, forfeiture,
      or
      nonrenewal of any permit, license, authorization, or approval applicable to
      the
      business, or operations or any of the assets or properties of the
      Company.




**5.4**  Valid
      Issuance .
      The
      Conversion Shares to be issued sold and delivered upon conversion of this Note,
      in accordance with the terms hereof and for the consideration expressed herein,
      will be duly and validly issued, fully paid and nonassessable. Any additional
      shares of Common Stock issuable, in accordance with the terms of Section 3.4 ,
      will be
      duly and validly issued, fully paid and nonassessable.




**5.5**  Seniority
      of Note. Until
      cancellation or conversion as provided for in this Note, after the Maturity
      Date
      (or earlier upon and as of an Event of Default), this Note shall be senior
      to
      all other debt obligations of the Company evidenced by any loan agreement,
      note
      or other instrument of any similar kind (other than the Original Promissory
      Note, the Company’s indebtedness under which shall rank pari passu with the
      indebtedness of the Company hereunder), and, after the Maturity Date (or earlier
      upon and as of an Event of Default), no payment(s) shall be made under any
      such
      other debt obligations (other than the Original Promissory Note) until OccuLogix
      has received payment in full of the Principal Amount.




**5.6**  Current
      Liabilities .
      The
      current liabilities of the Company as of June 30, 2006 do not exceed
      $4,030,400.




**6.**  Representations
      and Warranties of OccuLogix .
      OccuLogix hereby represents and warrants to the Company as follows:




**6.1**  Organization .
      OccuLogix is a corporation duly organized, validly existing and in good standing
      under the laws of the State of Delaware and has all requisite corporate power
      and authority to carry on its business as now conducted. OccuLogix has all
      requisite corporate power and authority to perform its obligations under, and
      carry out the provisions of, this Note.






**6.2**  Authorization;
      Binding Obligations; Governmental Consents .




(a)  All
      corporate action on the part of OccuLogix, its officers, directors and
      stockholders necessary for the performance of all obligations of OccuLogix
      hereunder, have been taken prior to the date hereof. This Note is a valid and
      legally binding obligation of OccuLogix, enforceable in accordance with its
      terms, except (i) as limited by applicable bankruptcy, insolvency,
      reorganization, moratorium, and other laws of general application affecting
      enforcement of creditors’ rights, and (ii) as limited by laws relating to the
      availability of specific performance, injunctive relief, or other equitable
      remedies.




(b)  No
      consent, approval, permit, order or authorization of, or registration,
      qualification, designation, declaration or filing with, any federal, state
      or
      local governmental authority on the part of OccuLogix is required in connection
      with the execution and issuance of this Note.




**6.3**  Investment
      Representations .
      OccuLogix understands that neither this Note nor the Conversion Shares have
      been
      registered under the Securities Act of 1933, as amended (the “ Securities
      Act ”).
      OccuLogix also understands that this Note and the Conversion Shares are being
      offered and sold pursuant to an exemption from registration contained in the
      Securities Act based in part upon OccuLogix’s representations contained in this
      Note. OccuLogix hereby represents and warrants as follows:




(a)  *Acquisition
      for Own Account* .
      OccuLogix is acquiring this Note and would acquire the Conversion Shares for
      OccuLogix’s own account for investment only, and not with a view toward their
      distribution.




(b)  *Accredited
      Investor* .
      OccuLogix represents that it is an “accredited investor” within the meaning of
      Regulation D under the Securities Act.




**7.**  Affirmative
      Covenants .
      Unless
      OccuLogix shall otherwise agree in writing, the Company covenants and agrees
      that, so long as this Note is outstanding:




**7.1**  Punctual
      Payment .
      The
      Company will duly and punctually pay, or cause to be paid, the Principal Amount
      and interest under this Note and all other amounts provided for in this Note,
      all in accordance with the terms hereof;




**7.2**  Notices .




(a)  Defaults .
      The
      Company will, promptly upon becoming aware thereof, notify OccuLogix in writing
      of any Event of Default, together with a reasonably detailed description
      thereof, and the actions the Company proposes to take with respect thereto;
      and




(b)  Notice
      of Litigation and Judgments .
      The
      Company will give notice to OccuLogix in writing within fifteen (15) business
      days of becoming aware of any litigation or proceedings threatened in writing
      or
      any pending litigation and proceedings affecting the Company or to which the
      Company is or becomes a party involving an uninsured claim against the Company
      that could, in each case, reasonably be expected to have a Material Adverse
      Effect and stating the nature and status of such litigation or proceedings;
      and
      the Company will give notice to OccuLogix, in writing, in form and detail
      reasonably satisfactory to OccuLogix, within ten (10) business days of any
      judgment not covered by insurance, final or otherwise, against the
      Company;




**7.3**  Legal
      Existence and Good Standing. The
      Company will do, or cause to be done, all things necessary to preserve and
      keep
      in full force and effect its legal existence and good standing in the State
      of
      Delaware and its good standing and qualification to transact or do business
      in
      each jurisdiction in which the failure to so qualify or be in good standing
      would have a Material Adverse Effect;




**7.4**  Taxes .
      The
      Company will duly pay and discharge, or cause to be paid and discharged, before
      the same shall become overdue, all taxes, as well as all claims for labor,
      materials, or supplies that if unpaid might by law become a lien or charge
      upon
      any of its property or assets;




**7.5**  Inspection
      of Properties and Books, etc .
      The
      Company shall permit OccuLogix upon five (5) business days’ written notice to
      the Company and through its designated representatives, to visit and inspect,
      during regular business hours on a business day, any of the properties of the
      Company, to examine the books of account of the Company (and to make copies
      thereof and extracts therefrom), and to discuss the affairs, finances and
      accounts of the Company with, and to be advised as to the same by, its officers,
      all at such reasonable times and intervals as OccuLogix may reasonably request;




**7.6**  Covenant
      of the Company to Reserve Stock .
      At all
      times prior to the earlier of (a) the conversion of this Note into Conversion
      Shares in accordance with the terms hereof, or (b) the Maturity Date, the
      Company shall reserve, out of its authorized and unissued capital stock, an
      adequate number of shares of Common Stock such that the Conversion Shares shall
      be immediately issuable upon conversion of this Note. If at any time the number
      of authorized but unissued shares of capital stock shall not be sufficient
      to
      enable the conversion of this Note into Conversion Shares, the Company will
      take
      such corporate action as may be necessary to increase its authorized but
      unissued shares of capital stock to such number of shares of capital stock
      as
      shall be sufficient for such purpose;




**7.7**  Use
      of
      Proceeds .
      The
      Company shall use the Principal Amount for general corporate purposes;
      and




**7.8**  Exemption
      from Rights of Participation .
      The
      Company shall (a) obtain continuing and effective written waivers, in a form
      reasonably satisfactory to OccuLogix, or (b) cause to be amended, as soon as
      practicable, Section 7.5 of the Amended and Restated Stockholders Agreement,
      so
      as to ensure in either case that the rights of participation of each of Boston
      Scientific Corporation and the Trustees of Boston University, established by
      Section 7 of the Amended and Restated Stockholders Agreement, shall have no
      application to any Conversion Shares to be issued to OccuLogix in the event
      of
      the conversion of this Note pursuant to Section 3.2 or any
      subsequent issuances of shares of the capital stock of the Company as a result
      of any anti-dilution rights of OccuLogix (as set forth in Section 3.4 ).




**8.**  Negative
      Covenants .
      Without
      limiting the foregoing, the Company covenants and agrees that it shall not,
      so
      long as this Note is outstanding, directly or indirectly do or cause, or propose
      to do or cause, any of the following without the prior written consent of
      OccuLogix:




**8.1**  Charter
      Documents .
      Cause
      or permit any amendments to its certificate of incorporation or by-laws or
      similar organizational documents, each as in effect on the date hereof, to
      the
      extent it could reasonably be expected to cause a material impairment of any
      rights of OccuLogix under this Note;




**8.2**  Dividends;
      Changes in Capital Stock .
      Except
      as otherwise specifically contemplated in this Note, (a) declare or pay any
      cash
      dividends or dividends of property on, or make any other distributions (in
      cash
      or property) in respect of, any of its capital stock, or (b) repurchase or
      otherwise acquire, directly or indirectly, any shares of its capital stock
      (other than pursuant to repurchase rights of the Company that permit the Company
      to repurchase securities from the holders thereof at the original purchase
      price
      therefor in connection with the termination of services of such holder as an
      employee of or consultant to the Company);




**8.3**  Dispositions .
      Sell,
      lease, license or otherwise dispose of or encumber any of its properties or
      assets which are material, individually or when aggregating all such
      dispositions taking place in any 12-consecutive-month period, taken as a whole,
      to the conduct of the Company’s business, or that could otherwise be reasonably
      expected to have a Material Adverse Effect, except as part of a Sale of the
      Company;




**8.4**  Related
      Party Transactions .
      Enter
      into or be a party to any transaction with any director, officer, employee,
      significant stockholder or family member of or consultant to any such person,
      corporation or other entity of which any such person beneficially owns 10%
      or
      more of the equity interests or has 10% or more of the voting power, or
      subsidiary or affiliate of the Company (a “ Related-Party
      Transaction ”)
      except
      as previously approved by (i) a majority of the independent members of the
      Company’s Board of Directors or (ii) the holders of a majority of the
      Independent Shares. Any Related-Party Transaction shall be fair and reasonable
      to the Company and on terms no less favorable to the Company than those that
      could be obtained from unaffiliated third parties. For purposes of this Section 8.4 ,
      “ Independent
      Shares ”
shall
      mean, with respect to any transaction, the shares of outstanding capital stock
      of the Company held by stockholders who are not directly interested in such
      transaction;




**8.5**  Breach
      or Violate Note. Take any
      action that could reasonably be expected to materially violate or breach, or
      result in a material violation or breach, of the Company’s obligations under
      this Note;




**8.6**  No
      Impairment .
      Take
      any action that could reasonably be expected to deny OccuLogix the anticipated
      benefits of the conversion rights provided in this Note in any material respect,
      or, if this Note is not so converted, the payment of the Principal Amount or
      unpaid accrued interest pursuant to the terms of this Note; or




**8.7**  General .
      Authorize, commit to, agree to take, or permit to occur any of the foregoing
      actions.




**9.**  Independent
      Obligations .
      The
      Company agrees and acknowledges that each covenant contained in Sections 7 and 8 constitutes an independent obligation of the Company, not qualified by any
      other
      clause, and shall be deemed to be cumulative.




**10.**  No
      Security Interest .
      This
      Note is unsecured and the Company does not pledge any assets or other collateral
      as security for the payment of the Principal Amount and interest described
      in
      this Note.




**11.**  Reasonable
      Estimate of Damages .
      After
      negotiation, the Company and OccuLogix have mutually agreed that, considering
      all of the circumstances existing on the date hereof, the right of OccuLogix
      to
      convert this Note pursuant to Section 3.2 ,
      and the
      attendant consequences of doing so, represent fair and reasonable compensation
      for damages that OccuLogix would suffer as a result of the existence of the
      conditions giving rise to such right. The granting of such right is not intended
      as a forfeiture or penalty but, rather, is intended to constitute liquidated
      damages to OccuLogix. The Company hereby specifically confirms the accuracy of
      the foregoing and its agreement therewith. Nothing contained in this Section 11 shall be
      deemed or construed as a limitation on any other rights or remedies that
      OccuLogix may have hereunder, at law or in equity, or otherwise.




**12.**  Waiver
      of Presentment, Etc .
      The
      Company hereby, to the fullest extent permitted by applicable law, waives
      presentment, demand, notice, protest, and all other demands and notices in
      connection with delivery, acceptance, performance, default, acceleration or
      enforcement of or under this Note.




**13.**  Amendment;
      Waivers .
      Neither
      this Note nor any term hereof may be waived, amended, discharged, modified,
      changed, or terminated orally, nor shall any waiver of any provision hereof
      be
      effective except by an instrument in writing signed by the party granting the
      waiver. The failure of the holder hereof to exercise any of its rights,
      remedies, powers, or privileges hereunder in any instance will not constitute
      a
      waiver thereof, or of any other right or remedy, and no single or partial
      exercise of any right or remedy shall preclude any other or further exercise
      thereof or of any other right or remedy.




**14.**  Payment
      of Collection Costs .
      The
      Company will pay on demand all costs of collection, including all court costs
      and reasonable attorneys’ fees, paid or incurred by OccuLogix in enforcing this
      Note after an Event of Default.




**15.**  GOVERNING
      LAW .
      THIS
      NOTE WILL BE GOVERNED BY AND INTERPRETED AND CONSTRUED IN ACCORDANCE WITH THE
      INTERNAL LAWS OF THE COMMONWEALTH OF MASSACHUSETTS (WITHOUT REFERENCE TO
      PRINCIPLES OF CHOICE OF LAW).




**16.**  Notices .
      All
      notices and other communications required or permitted hereunder shall be in
      writing and shall be deemed to have been duly given when delivered in person
      or
      upon confirmation of receipt when transmitted by facsimile transmission (but
      only if followed by national overnight courier or hand for delivery on the
      next
      business day) or on receipt after dispatch by registered or certified mail,
      post
      prepaid, addressed, or on the next business day if transmitted by national
      overnight courier, in each case as follows:




If
      to the
      Company:




Solx,
      Inc.


8
      Saint
      Mary’s Street


Suite
      629


Boston,
      MA 02215


Attention:
      President


Telephone:
      617-353-1277


Facsimile:
      617-358-1933




with
      a
      copy to:




Rackemann,
      Sawyer & Brewster


Professional
      Corporation


One
      Financial Center


Boston,
      MA 02111


Attention:
      Jamey A. Wachta, Esq.


Telephone:
      617-951-1141


Facsimile:
      617-542-7437




If
      to
      OccuLogix, Inc.:




OccuLogix,
      Inc.


2600
      Skymark Avenue


Building
      9


Suite
      201


Mississauga,
      ON Canada L4W5B2


Attention:
      Chief Executive Officer


Facsimile:
      905-602-7623




With
      a
      copy to:




Torys
      LLP


Suite
      3000


79
      Wellington Street West


Toronto-Dominion
      Centre


Toronto,
      ON Canada M5K 1N2


Attention:
      David A. Chaikof


Facsimile:
      416-865-7380





**In
      Witness Whereof** ,
      the
      Company has executed and delivered this Convertible Unsecured Promissory Note
      as
      an instrument under seal as of the date first above written.


**SOLX,
                  INC.**By:
              /s/
                  Doug P. AdamsName:
              Doug
                  P. AdamsTitle:
              President




**Acknowledged
                  and Agreed:**
                
                
                **OCCULOGIX,
                  INC.**By:
              /s/ Elias VamvakasName:
              Elias
                  VamvakasTitle:
              Chairman
                  and Chief Executive Officer