<PAGE>
                                                                   Exhibit 10.31




                         SEVERANCE AND RELEASE AGREEMENT

         This Severance and Release Agreement (this "AGREEMENT") is entered into
by and between Eyetech Pharmaceuticals, Inc. (the "COMPANY") and Douglas H.
Altschuler ("ALTSCHULER").

         WHEREAS, Altschuler has been employed by the Company since May 2003 and
entered into an Employment Agreement, dated as of August 25, 2003, with the
Company (the "OLD AGREEMENT");

         WHEREAS, Altschuler has asked to resign, and the Company has agreed to
accept such resignation and to terminate the Old Agreement; and

         WHEREAS, the Company and Altschuler wish to make arrangements for
payments and other good and valuable consideration as set forth in this
Agreement, in consideration of Altschuler's agreement to comply with the
cooperation, non-solicitation and other provisions set forth in this Agreement,
which consideration Altschuler hereby acknowledges is sufficient consideration
for such provisions and are not unreasonable or overly burdensome on Altschuler.

         NOW, THEREFORE, in consideration of the mutual covenants and promises
of the parties hereto, Altschuler and the Company agree as follows:

         1. SEVERANCE OF EMPLOYMENT.

                  (a) Altschuler and the Company agree that Altschuler's
employment with the Company and, except as provided herein, the Old Agreement
will terminate as of March 18, 2005 (the "TERMINATION DATE"). Effective as of
March 17, 2005, Altschuler also resigns from all positions at the Company's
subsidiaries, including those set forth on Schedule I hereto. Altschuler shall
execute such resignation letters as the Company may reasonably request.

                  (b) Promptly following the Termination Date, Altschuler shall
be paid the allocable portion of his current Base Salary of $275,000 through the
Termination Date, and any unused vacation time accrued through the Termination
Date, and shall be entitled to elect continuation of benefits under the
Consolidated Omnibus Budget Reconciliation Act of 1985, as amended ("COBRA"),
and the reimbursement of expenses through the Termination Date in accordance
with the Company's policies.

                  (c) Upon effectiveness of this Agreement in accordance with
the provisions of Section 15(a)(iv), Altschuler shall be entitled to receive
from the Company in the future the payments and other benefits specified in
Section 2.

                  (d) All payments made to Altschuler by the Company hereunder
shall be subject to any applicable withholding taxes.
<PAGE>
         2. SEVERANCE BENEFITS.

                  (a) SEVERANCE PAYMENT. The Company shall pay Altschuler 12
monthly payments each equal in amount to 1/12th of his Base Salary of $275,000
as of the Termination Date, less applicable state and federal withholdings.

                  (b) HEALTH INSURANCE. The Company shall, for a period of 12
months (or until comparable benefits coverage becomes available to Altschuler,
if sooner), reimburse Altschuler (or pay Altschuler directly, at the Company's
option) the costs associated with the continuation of his and his dependents'
medical and dental benefits under COBRA as in effect immediately prior to the
Termination Date. As of the first anniversary of the Termination Date unless
terminated earlier in accordance with the preceding sentence, Altschuler will be
solely responsible for all applicable COBRA premiums.

                  (c) OPTIONS. The Company has previously granted Altschuler
options to purchase shares of the Company's common stock as set forth in
Schedule II to this Agreement, which Schedule also identifies the number of
shares subject to vested options as of the Termination Date, including the
additional number of shares with respect to which the Company has agreed to
accelerate vesting (or to allow the lapse of applicable repurchase rights) to
March 17, 2005 (the "VESTED OPTIONS"). As provided in the agreements pursuant to
which the Vested Options were issued and subject to the terms of such
agreements, Altschuler shall be entitled to exercise the Vested Options within
three months after the Termination Date. Immediately following effectiveness of
this Agreement in accordance with Section 15(a)(iv), the Company shall (i)
deliver to Altschuler stock certificate No. EYE0887 for 6,000 shares of common
stock that was previously issued in his name, free of all repurchase
restrictions imposed by the Company, and (ii) cancel all remaining unvested
options.

         3. RELEASE AND WAIVER OF CLAIMS; COVENANT NOT TO SUE.

                  Altschuler hereby waives and releases and promises never to
assert any claims or causes of action, whether or not now known to the greatest
extent of all applicable law, against the Company or its predecessors,
successors, or past or present subsidiaries or affiliated entities, officers,
directors, agents, employees and assigns, with respect to any matter (without
limitation) arising out of or connected with his employment with the Company or
the termination of that employment, including without limitation, claims of
wrongful discharge, constructive discharge, emotional distress, defamation,
invasion of privacy, fraud, breach of contract, breach of the covenant of good
faith and fair dealing, any claims of discrimination or harassment based on sex,
age, race, national origin, disability or on any other basis and all common law
claims and all other laws and regulations relating to employment, including
without limitation, all claims under Title VII of the Civil Rights Act of 1964,
42 U.S.C. Section 2000e et seq., the Age Discrimination in Employment Act, 29
U.S.C. Section 621 et seq., the Americans With Disabilities Act of 1990, 42
U.S.C. Section 12101 et seq., the New York Human Rights Law, N.Y. Exec. Law
Section 290 et seq., the New York Civil Rights Law, N.Y. Civ. Rights Law Section
79-e et seq., the New York Equal Rights Law, N.Y. Civ. Rights Law Section 40c et
seq., N.Y. Civ. Rights Law Section 47 et seq. (New York rights of persons with
disabilities law), N.Y. Lab. Law Section 194 et seq. (New York equal pay law),
N.Y. Lab. Law Section 740 (New York whistleblower protection law), New York City
Human

                                       2
<PAGE>
Rights Law, N.Y.C. Admin. Code Section 8-101 et seq., all as amended; all claims
arising out of the Family and Medical Leave Act, 29 U.S.C. Section 2601 et seq.,
the Fair Credit Reporting Act, 15 U.S.C. Section 1681 et seq., and the Employee
Retirement Income Security Act of 1974 ("ERISA"), 29 U.S.C. Section 1001 et
seq., all as amended. Further, Altschuler hereby agrees not to sue the Company
or its predecessors, successors, or past or present subsidiaries or affiliated
entities, officers, directors, agents, employees and assigns, for any released
claim.

         4. COOPERATION OBLIGATIONS.

                  (a) Promptly after the execution and delivery hereof,
Altschuler agrees to be available from time to time to provide additional
information about the operations of the Company to Morrison & Foerster LLP or
other counsel mutually acceptable to the Company and Altschuler.

                  (b) For a period from March 18 through April 18, 2005, the
Company will arrange for an automatic message containing forwarding information
on Altschuler's Company email address.

                  (c) Altschuler may use the services of Harry Brown, his former
administrative assistant for up to two hours per day during regular business
hours through March 24, 2005.

         5. LIMITED NON-SOLICITATION. For a period of one year after the date
hereof, Altschuler will not, without the prior written approval of the Company,
directly or indirectly, personally or through others solicit or attempt to
solicit (on his own behalf or on behalf of any other person or entity) any
employee or any consultant of the Company to end their relationship with the
Company or to hire or attempt to hire (on his own behalf or on behalf of any
other person or entity) any such employee or consultant. Altschuler understands
that this Section 6 is a material inducement to the Company for the making of
this Agreement and that, for the breach thereof the Company will be entitled to
pursue its legal and equitable remedies, including, without limitation, the
right to seek injunctive relief.

         6. SECURITIES LAWS MATTERS. Altschuler acknowledges that (1) he will
remain subject to the short-swing profit recovery and filing requirements of
Section 16 through September 17, 2005, six months after Termination Date,
(2) he will continue to be considered an "affiliate" of the Company under Rule
144 under the Securities Act of 1933, as amended, until June 17, 2005, and (3)
effective upon termination of his employment with the Company, he will no
longer be subject to the Company's insider trading policy.

         7. NO COERCION. No statements or conduct by the Company has in any way
coerced or unduly influenced Altschuler to enter into this Agreement.

         8. CONTINUING OBLIGATIONS. At all times in the future, Altschuler shall
remain bound by the terms of Section 3 of the Old Agreement and the
Non-Disclosure and Proprietary Information Agreement for Employees, between
Altschuler and the Company and the Termination Certification in connection
therewith attached hereto as Exhibit A, which shall be considered a part of this
agreement (collectively, the "NON-DISCLOSURE AND PROPRIETARY INFORMATION
AGREEMENT").

                                       3
<PAGE>
         9. WHOLE AGREEMENT. Altschuler and the Company agree that except as
expressly provided herein, this Agreement (including all exhibits and schedules
and the Non-Disclosure and Proprietary Information Agreement), shall supersede
and render null and void any and all prior agreements between the parties,
including, but not limited to, the Old Agreement. The parties further agree that
this Agreement constitutes the entire agreement between the parties regarding
the subject matter thereof, and that such Agreements may be modified only in a
written document executed by Altschuler and a duly authorized officer of the
Company.

         10. CHOICE OF LAW. The validity, interpretation, construction and
performance of this Agreement shall be governed by the laws of the State of New
York as a contract entered into and performed entirely within the State of New
York (other than their choice-of-law provisions).

         11. SUBMISSION TO JURISDICTION. Any controversy involving the
construction or application of any terms, covenants or conditions of this
Agreement, or any claims arising out of any alleged breach of this Agreement
shall be settled by the courts in New York in the County of New York. Altschuler
hereby irrevocably submits to the jurisdiction of the courts of the State of New
York, or if appropriate, a federal court located in New York (which courts, for
purposes of this Agreement, are the only courts of competent jurisdiction), over
any suit, action or other proceeding arising out of, under, or in connection
with this Agreement or its subject matter.

         12. ASSIGNMENT AND SUCCESSORS. Neither party shall assign any right or
delegate any obligation hereunder without the other party's written consent and
any purported assignment or delegation by a party hereto without the other
party's written consent shall be void, except that the Company may assign this
Agreement in connection with a business combination (whether by merger, sale of
assets or otherwise) with another entity without Altschuler's consent. This
Agreement shall be binding upon and inure to the benefit of the Company, and its
successors, and Altschuler, his heirs, executors, administrators and legal
representatives.

         13. SEVERABILITY. The invalidity or unenforceability of any provision
of this Agreement shall not affect the validity or enforceability of any other
provision hereof, which shall remain in full force and effect.

         14. COUNTERPARTS. This Agreement may be executed in two counterparts,
each of which shall constitute an original, but all of which taken together
shall constitute one and the same instrument. Execution of a facsimile copy
shall have the same force and effect as execution of an original, and a
facsimile signature shall be deemed an original and valid signature.

         15. REVIEW AND REVOCATION.

                  (a) Altschuler hereby acknowledges, understands and agrees
that:

                           (i) Altschuler may have, and has had, at least 21
days after receipt of this Agreement within which he may review and consider it,
discuss it with an attorney of

                                       4
<PAGE>
his own choosing, and decide to execute or not execute this Agreement; by
execution of this Agreement; Altschuler waives any claim that he has not
received the full 21 day review period;

                           (ii) Altschuler has seven days after the execution of
this Agreement within which he may revoke this Agreement; provided, however,
that his exercise of any of the options identified under the column "Additional
Vesting Pursuant to this Agreement" in Schedule II or any other exercise of his
rights under this Agreement during such seven-day period, will be deemed a
waiver of such revocation right;

                           (iii) In order to revoke this Agreement, Altschuler
must deliver to the Company, Attn: Clare M. Carmichael, Vice President, Human
Resources, on or before seven days after the execution of this Agreement, a
letter stating that he is revoking this Agreement; and

                           (iv) This Agreement shall not become effective or
enforceable until after the expiration of seven days following the date
Altschuler executes this Agreement.

                  (b) The parties agree they have read and understand this
Agreement, and that they affix their signatures hereto voluntarily and without
coercion. Altschuler further acknowledges that he has had or has waived his
right to have at least 21 days within which to consider this Agreement, that he
was advised by the Company to consult with an attorney of his own choosing
concerning the waivers contained in and the terms of this Agreement, and that
the waivers he has made and the terms he has agreed to herein are knowing,
conscious and with full appreciation that he is forever foreclosed from pursuing
any of the rights so waived.

                      [Balance of page intentionally blank]



                                       5
<PAGE>
         IN WITNESS WHEREOF, the Company and Altschuler have executed this
Severance and Release Agreement as of the dates indicated below, the later date
to be the date of this Agreement.

Dated:  March 18, 2005                  /s/ Douglas H. Altschuler
                                        ------------------------------
                                        Douglas H. Altschuler


                                        EYETECH PHARMACEUTICALS, INC.


                                        By:    /s/ Paul Chaney
                                              ------------------------
                                        Name:  Paul Chaney
Dated:  March 18, 2005                  Title: Chief Operating Officer
<PAGE>
                                   SCHEDULE I

                            POSITIONS AT SUBSIDIARIES

Eyetech Pharmaceuticals Boulder, Inc.                Director and Secretary

Eyetech Pharmaceuticals (Ireland) Limited            Director
<PAGE>
                                   SCHEDULE II

                    OPTIONS GRANTED TO DOUGLAS H. ALTSCHULER

                              As of March 18, 2005

<TABLE>
<CAPTION>
                                         Options
                        ----------------------------------------
   Date of                      Additional Vesting
  Agreement                         Pursuant to
   (ISO/NQ)             Vested    this Agreement    Unvested (2)  Exercise Price
   --------             ------    --------------    ------------  --------------
<S>                     <C>     <C>                 <C>           <C>
 7/7/03 (NQ)            12,548        92,857               --         $ 3.50
 7/7/03 (ISO)                          4,214(1)                       $ 3.50
                                       2,929            8,333
2/19/04 (NQ)             3,176            --            5,961         $29.91
2/19/04 (ISO)            1,824            --            9,039         $29.91
12/9/04 (NQ)                --            --           25,000         $43.55
</TABLE>

(1) The option with respect to these shares was exercised. The repurchase right
with respect to these remaining shares will lapse pursuant to this Agreement.

(2) The unvested options will be canceled upon effectiveness of this Agreement.
<PAGE>
                                    EXHIBIT A

                          EYETECH PHARMACEUTICALS, INC.

                            TERMINATION CERTIFICATION

         Capitalized terms used in this Termination Certification that are not
defined herein have the same meaning given to them in the Non-Disclosure and
Proprietary Information Agreement (the "Proprietary Information Agreement")
between Eyetech Pharmaceuticals, Inc. (the "Company") and me.

         This is to certify that I do not have in my possession, nor have I
failed to return, any devices, records, data, notes, reports, proposals, lists,
correspondence, specifications, drawings, blueprints, sketches, materials,
equipment, other documents or property, or reproductions of any aforementioned
items belonging to the Company Group.

         I further certify that I have complied with all the terms of the
Proprietary Information Agreement, including the reporting of any inventions and
original works of authorship (as defined therein), conceived or made by me
(solely or jointly with others) covered by the Proprietary Information
Agreement.

         I further agree that, in compliance with the Proprietary Information
Agreement, I will preserve as confidential all trade secrets, confidential
knowledge, data or other proprietary information relating to products,
processes, know-how, designs, formulas, developmental or experimental work,
computer programs, data bases, other original works of authorship, customer
lists, business plans, financial information or other subject matter pertaining
to any business of the Company Group or any of its employees, clients, Employees
or licensees.

         I hereby acknowledge and reaffirm all of my obligations under the
Proprietary Information Agreement, including, without limitation, the provisions
relating to non-solicitation of employees (Paragraph 6 of the Proprietary
Information Agreement).

Dated as of March 18, 2005
                                             _______________________________
                                             Douglas H. Altschuler