<PAGE>   1

                                                                   EXHIBIT 10.18


                AMENDED AND RESTATED INTER-COMPANY LOAN AGREEMENT


        This Amended and Restated Inter-Company Loan Agreement (this
"AGREEMENT") is made and entered into effective as of June 1, 1999 (the
"EFFECTIVE DATE") by and between Ocular Sciences, Inc., a Delaware corporation
("OSI"), and Precision Lens Manufacturing & Technology, Inc., a Barbados
corporation ("PLMT"), and replaces and supersedes in its entirety that certain
Inter-Company Loan Agreement dated as of March 1, 1999 (the "ORIGINAL DATE") by
and between OSI and PLMT.

                                    RECITALS

        WHEREAS, on March 1, 1999 PLMT entered into an Inter-Company Loan
Agreement providing for the loan of up to $20,000,000 from OSI to PLMT and PLMT
executed and delivered to OSI a Revolving Secured Promissory Note in the
principal sum of $20,000,000 (the "ORIGINAL NOTE");

        WHEREAS, PLMT now wishes to borrow up to an additional $70,000,000 from
OSI, its parent corporation, from time to time, on and subject to the terms and
conditions contained in this Agreement;

        WHEREAS, OSI is willing to provide loans of up to an aggregate of
$90,000,000 to PLMT from time to time, on and subject to the terms and
conditions contained in this Agreement;

        NOW, THEREFORE, in consideration of the mutual promises,
representations, warranties, covenants and conditions set forth in this
Agreement, OSI and PLMT hereby agree as follows:

        1. CERTAIN DEFINITIONS. As used herein:

                1.1 BUSINESS DAY. The term "BUSINESS DAY" means any day other
than a Saturday, Sunday, or other day on which commercial banks in San Mateo
County, California are authorized or required by law to close.

                1.2 LOAN DOCUMENTS. The term "LOAN DOCUMENTS" means,
collectively, this Agreement, the Replacement Note (as defined below) executed
and delivered pursuant hereto and any other documents executed or delivered by
OSI or PLMT pursuant to this Agreement or in connection with any Loan (as
defined below).

                1.3 LOAN PERIOD. The term "LOAN PERIOD" means that period of
time beginning on the Original Date and ending on the Maturity Date.



<PAGE>   2

                1.4 MATURITY DATE. The term "MATURITY DATE" means that date
which is the earlier to occur of: (a) March 1, 2004; (b) the sale of all or
substantially all the assets of PLMT; (c) the merger or consolidation of PLMT
with or into another company or other reorganization of PLMT following which the
shareholders of PLMT immediately prior to such transaction do not own at least
51% of the company emerging as the survivor or parent company in such
transaction; (d) the date the OSI Loan Facility (as defined in Section 2.1) is
terminated pursuant to Section 5.2(a); (e) the date on which OSI declares the
entire unpaid principal amount and all accrued interest on an outstanding Note
immediately due and payable in full pursuant to the terms of such Note or under
Section 5.2(b), or such amount otherwise becomes immediately due and payable in
full; or (f) the date on which OSI and PLMT mutually agree to terminate this
Agreement.

        2. AMOUNT AND TERMS OF LOAN.

                2.1 OSI LOAN FACILITY. Subject to all the terms and conditions
of this Agreement, and in reliance on the representations, warranties and
covenants of PLMT set forth in this Agreement, OSI agrees to make loans of funds
to PLMT, in each case subject to the sole discretion of OSI, during the Loan
Period on a revolving basis (such loans being collectively hereinafter referred
to as "LOANS" and each individually as a "LOAN"), in an aggregate cumulative
total principal amount outstanding at any one time not to exceed Ninety Million
Dollars (US$90,000,000). Loans may be requested and drawn down by PLMT as and
when PLMT needs such sums for general corporate purposes upon two (2) Business
Days written notice to OSI. OSI in its sole discretion, for any reason or no
reason and without liability to PLMT, may refuse to provide one or more Loans
requested by PLMT. OSI's obligation to consider requests for Loans to PLMT under
this Agreement is referred to as the "OSI LOAN FACILITY". PLMT's indebtedness to
OSI for Loans advanced by OSI under this Agreement will be evidenced by a
Promissory Note of PLMT in the form attached hereto as Exhibit "A" (the
"REPLACEMENT NOTE").

                2.3 MATURITY. Unless payment thereof is accelerated or otherwise
becomes due earlier under the terms of this Agreement (including but not limited
to the provisions of Section 5.2), the unpaid principal amount of all Loans and
all unpaid interest accrued thereon, together with any other fees, expenses or
costs incurred in connection therewith, will be immediately due and payable to
OSI in full on the earlier of the Maturity Date or the Payment Date set forth in
the Replacement Note.

                2.4 CANCELING OR REDUCING LOAN FACILITY. Upon ten (10) calendar
days written notice to PLMT, OSI may cancel the OSI Loan Facility or reduce the
amount of the OSI Loan Facility. Upon OSI providing a notice electing to cancel
the amount of the OSI Loan Facility made available to PLMT hereunder, the
Replacement Note shall be deemed automatically converted, without further action
required on the part of either party hereto, into a non-revolving fixed
promissory note, due on the Payment Date set forth in such Replacement Note, in
a principal amount equal to then aggregate principal amount of all Loans
outstanding under such Replacement Note plus accrued interest thereon, and will
bear interest from such date forward at the rate specified in such Replacement
Note, and no further Loans will be made by



                                       2
<PAGE>   3

OSI to PLMT under such Replacement Note or this Agreement. Upon OSI providing a
notice electing to reduce the amount of the OSI Loan Facility made available to
PLMT hereunder, the Replacement Note shall be deemed automatically converted,
without further action required on the part of either party hereto, into a
promissory note, due on the Payment Date set forth in such Replacement Note, in
a principal amount equal to the amount to which the OSI Loan Facility is so
reduced and all other terms of the Replacement Note shall remain unchanged.

                2.5 PAYMENT OF AMOUNTS OWING; OFFSET. Upon the earliest to occur
of the Payment Date set forth in the Replacement Note or the Maturity Date
specified in this Agreement, OSI shall provide PLMT written notice of the
aggregate amount of principal and accrued interest owing to OSI by PLMT as of
such date under the Replacement Note and this Agreement and such amounts shall
be offset against any amounts then owing by OSI to PLMT, if any, and the net
amount owing to OSI shall be immediately due and payable by PLMT.

        3. REPRESENTATIONS AND WARRANTIES OF PLMT. PLMT hereby represents and
warrants to OSI that:

                3.1 ORGANIZATION AND STANDING. PLMT is a corporation duly
organized, validly existing and in good standing under the laws of Barbados, and
has all requisite corporate power and authority to own, lease and operate its
properties and to conduct its business as such is presently conducted and as
proposed to be conducted.

                3.2 AUTHORIZATION. All corporate action on the part of PLMT and
its officers, directors and shareholders that is necessary for the
authorization, execution, delivery and performance of each of the Loan Documents
by PLMT has been taken; and each of the Loan Documents constitutes valid and
legally binding obligations of PLMT, enforceable in accordance with their terms.

        4. REPRESENTATIONS AND WARRANTIES OF OSI. OSI hereby represents and
warrants to PLMT that:

                4.1 ORGANIZATION AND STANDING. OSI 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 own, lease and
operate its properties and to conduct its business as such is presently
conducted and as proposed to be conducted.

                4.2 AUTHORIZATION. All corporate action on the part of OSI and
its officers, directors and shareholders that is necessary for the
authorization, execution, delivery and performance of each of the Loan Documents
by OSI has been taken; and each of the Loan Documents constitutes valid and
legally binding obligations of OSI, enforceable in accordance with their terms.

        5. EVENTS OF DEFAULT OF BORROWER.

                5.1 EVENTS OF DEFAULT. The occurrence of any of the following
events will constitute an "EVENT OF DEFAULT" under this Agreement and the
applicable Replacement Note:



                                       3
<PAGE>   4

                        (a) PLMT fails to pay any principal or any accrued
interest under any Replacement Note or any Loan when the same is due and
payable, or fails to pay any amount of principal or accrued interest due under
the Replacement Note or any Loan on the Payment Date or Maturity Date therefor,
and such failure to pay is not cured by PLMT within two (2) Business Days after
OSI gives written notice of such failure to pay to PLMT; or

                        (b) PLMT is in default under any other agreement, note
or instrument pursuant to which PLMT has borrowed money from OSI; or

                        (c) PLMT is in default with respect to any agreement or
other evidence of indebtedness or liability for borrowed money if the effect of
such default is to (i) to accelerate the maturity of such indebtedness or
liability or to require the prepayment thereof, or (ii) to permit the holder
thereof to cause such indebtedness to become due prior to the stated maturity
thereof;

                        (d) PLMT becomes insolvent, or admits in writing its
inability to pay its debts as they mature, or makes an assignment for the
benefit of creditors, or applies for or consents to the appointment of a
receiver, liquidator, custodian or trustee for it or for a substantial part of
its property or business, or such a receiver, liquidator, custodian or trustee
otherwise is appointed and is not discharged within thirty (30) calendar days
after such appointment;

                        (e) bankruptcy, insolvency, reorganization or
liquidation proceedings or other proceedings for relief under any bankruptcy law
or any law for the relief of debtors are instituted by or against PLMT, or any
order, judgment or decree is entered against PLMT decreeing its dissolution or
liquidation; provided, however, with respect to an involuntary petition in
bankruptcy, such petition is not dismissed within thirty (30) days after the
filing of such petition;

                        (f) a court order or judgment for the payment of money
in excess of US$500,000 is entered against PLMT; or

                        (g) the assets of PLMT are seized by or surrendered to
any governmental entity.

                5.2 REMEDIES OF OSI. Upon and after the occurrence of any Event
of Default, OSI will have no further obligation to make any Loan or Loans to
PLMT, and in addition, at OSI's sole option by written notice to PLMT, OSI may
take any one or more of the following actions:

                        (a) OSI may immediately terminate the Loan Facility it
provides hereunder and all other liabilities and obligations of OSI under this
Agreement, without affecting OSI's rights under this Agreement and the
Replacement Note; and

                        (b) OSI may declare the entire principal amount of and
all accrued interest on the Replacement Note and all Loans immediately due and
payable in full, whereupon



                                       4
<PAGE>   5

such amounts will immediately be due and payable in full, provided that in the
case of an Event of Default listed in paragraph (d), (e) or (g) of Section 5.1,
the principal and interest will immediately become due and payable without the
requirement of any notice or other action by OSI; and

                        (c) Exercise all rights and remedies granted under the
Loan Documents or otherwise available to OSI at law or in equity.

        6. SECURITY INTEREST.

                6.1 GRANT OF SECURITY INTEREST. PLMT hereby grants OSI a present
and continuing security interest in all of PLMT's right, title and interest in
and to and arising under that certain contract with Arthur D. Little, Inc. dated
August 17, 1995, as amended, regarding the contact lens automation project.

                6.2 FURTHER ASSURANCES. PLMT hereby covenants and agrees to take
all steps and execute and file all documents requested by OSI to document,
evidence and perfect such security interest in favor of OSI.

        7. MISCELLANEOUS.

                7.1 ENTIRE AGREEMENT. This Agreement and the Replacement Note
and schedules attached thereto constitute the entire agreement and understanding
among the parties with respect to the subject matter thereof and supersede any
prior understandings or agreements of the parties with respect to such subject
matter. The Replacement Note replaces and supersedes in its entirety the
Original Note, which is deemed canceled.

                7.2 GOVERNING LAW. This Agreement will be governed by and
construed in accordance with the internal laws of the State of California as
applied to agreements entered into solely between residents of, and to be
performed entirely in, such state, without reference to that body of law
relating to conflicts of law or choice of law.

                7.3 MODIFICATION; WAIVER. This Agreement may be modified or
amended only by a writing signed by both parties hereto. No waiver or consent
with respect to this Agreement will be binding unless it is set forth in writing
and signed by the party against whom such waiver is asserted. No course of
dealing between OSI and PLMT will operate as a waiver or modification of any
party's rights under this Agreement or any other Loan Document. No delay or
failure on the part of either party in exercising any right or remedy under this
Agreement or any other Loan Document will operate as a waiver of such right or
any other right. A waiver given on one occasion will not be construed as a bar
to, or as a waiver of, any right or remedy on any future occasion.

                7.4 RIGHTS AND REMEDIES CUMULATIVE. The rights and remedies of
OSI herein provided will be cumulative and not exclusive of any other rights or
remedies provided by law or otherwise.



                                       5
<PAGE>   6

                7.5 NOTICES. Any notice required or permitted under this
Agreement will be given in writing and will be deemed effectively given upon
personal delivery, upon confirmed transmission by telecopy or email, or three
(3) days following deposit with the United States Post Office, postage prepaid,
addressed:

                      To OSI:

                      475 Eccles Avenue
                      So. San Francisco, CA 94080
                      Attention: Chief Financial Officer

                      To PLMT:

                      c/o KPMG
                      Chartered Accountants
                      Hastings Christ Church
                      Barbados
                      Attention: General Manager


or at such other address as such party may specify by written notice given in
accordance with this Section.

                7.7 SEVERABILITY. Any invalidity, illegality or unenforceability
of any provision of this Agreement in any jurisdiction will not invalidate or
render illegal or unenforceable the remaining provisions hereof in such
jurisdiction and will not invalidate or render illegal or unenforceable such
provision in any other jurisdiction.

                7.7 ATTORNEYS' FEES. If any party hereto commences or maintains
any action at law or in equity (including counterclaims or cross-complaints)
against the other party hereto by reason of the breach or claimed breach of any
term or provision of this Agreement, any Note or any other Loan Document, then
the prevailing party in said action will be entitled to recover its reasonable
attorneys' fees and court costs incurred therein.

                7.8 SUCCESSORS AND ASSIGNS. This Agreement, and its rights and
obligations hereunder, may be transferred and assigned by OSI to any entity
which is controlled by, which controls, or is under common control with OSI. The
terms and conditions of this Agreement will inure to the benefit of and be
binding upon the respective successors and permitted assigns of the parties;
provided, however, that this Agreement may not be transferred, assigned or
delegated by PLMT, whether by voluntary assignment or operation of law, without
the prior written consent of OSI.

                7.9 COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which will be deemed an original, but all of which
together will constitute one and the same instrument.



                                       6
<PAGE>   7

        IN WITNESS WHEREOF, the parties have duly executed and delivered this
Agreement as of the Effective Date.


<TABLE>
<CAPTION>
OCULAR SCIENCES, INC.                              PRECISION LENS MANUFACTURING & TECHNOLOGY, INC.
<S>                                                <C>
Name: /s/ Gregory E. Lichtwardt                    Name: /s/ Fernando Vazquez
     -----------------------------------------          ------------------------------------------
By: Gregory E. Lichtwardt                          By: Fernando Vazquez
   -------------------------------------------        --------------------------------------------
Title: Vice President, Chief Financial Officer     Title: Director
      ----------------------------------------           -----------------------------------------
Executed at: South San Francisco, CA               Executed at: Rex Halcyon Cove, Antigua
            ----------------------------------                 -----------------------------------
</TABLE>


ATTACHMENTS:

Exhibit A - PLMT Revolving Secured Promissory Note - $90,000,000


                               [SIGNATURE PAGE TO
               AMENDED AND RESTATED INTER-COMPANY LOAN AGREEMENT]



                                       7