Power of Attorney

        Each of the undersigned entities and individuals (collectively, the
"Reporting Persons") hereby authorizes and designates Sofinnova Management VIII,
L.L.C. or such other person or entity as is designated in writing by Garheng
Kong (the "Designated Filer") as the beneficial owner to prepare and file on
behalf of such Reporting Person individually, or jointly together with the other
Reporting Persons, any and all reports, notices, communications and other
documents (including, but not limited to, reports on Schedule 13D, Schedule 13G,
Form 3, Form 4 and Form 5) that such Reporting Person may be required to file
with the United States Securities and Exchange Commission pursuant to the
Securities Act of 1933, as amended (together with the implementing regulations
thereto, the "Act") and the Securities Exchange Act of 1934, as amended
(together with the implementing regulations thereto, the "Exchange Act")
(collectively, the "Reports") with respect to each Reporting Person's ownership
of, or transactions in, securities of any entity whose securities are
beneficially owned (directly or indirectly) by such Reporting Person
(collectively, the "Companies").

        Each Reporting Person hereby further authorizes and designates Nathalie
Auber (the "Authorized Signatory") to execute and file on behalf of such
Reporting Person the Reports and to perform any and all other acts, which in the
opinion of the Designated Filer or Authorized Signatory may be necessary or
incidental to the performance of the foregoing powers herein granted.

        The authority of the Designated Filer and the Authorized Signatory under
this Document with respect to each Reporting Person shall continue until such
Reporting Person is no longer required to file any Reports with respect to the
Reporting Person's ownership of, or transactions in, the securities of the
Companies, unless earlier revoked in writing. Each Reporting Person acknowledges
that the Designated Filer and the Authorized Signatory are not assuming any of
the Reporting Person's responsibilities to comply with the Act or the Exchange
Act.

                              SOFINNOVA VENTURE PARTNERS VIII, L.P.,
                              a Delaware Limited Partnership


                              By:    SOFINNOVA MANAGEMENT VIII, L.L.C.,
                                     a Delaware Limited Liability Company
                                     Its General Partner


                              By:    /s/ Garheng Kong
                                     -------------------------------------------
                                     Garheng Kong
                                     Managing Member


                              SOFINNOVA MANAGEMENT VIII, L.L.C.,
                              a Delaware Limited Liability Company


                              By:    /s/ Garheng Kong
                                     -------------------------------------------
                                     Garheng Kong
                                     Managing Member


                              By:    /s/ James I. Healy
                                     -------------------------------------------


                              By:    /s/ Garheng Kong
                                     -------------------------------------------


                              By:    /s/ Michael F. Powell
                                     -------------------------------------------