EXHIBIT 10.43 COMMERCIAL SECURITY AGREEMENT

EXHIBIT 10.43

COMMERCIAL SECURITY AGREEMENT

THIS COMMERCIAL SECURITY AGREEMENT is entered into between SYNERGETICS, INC., a Missouri Corporation (referred to below as “Grantor”); and Union Planters Bank N.A. (referred to below as “Lender”). For valuable consideration, Grantor grants to Lender a security interest in the Collateral to secure the Indebtedness and agrees that Lender shall have the rights stated in this Agreement with respect to the Collateral, in addition to all other rights which Lender may have by law.

DEFINITIONS. The following words shall have the following meanings when used in this Agreement. Terms not otherwise defined in this Agreement shall have the meanings attributed to such terms in the Uniform Commercial Code. All references to dollar amounts shall mean amounts in lawful money of the United States of America.

Agreement. The word “Agreement” means this Commercial Security Agreement, as this Commercial Security Agreement may be amended or modified from time to time, together with all exhibits and schedules attached to this Commercial Security Agreement from time to time.

Collateral. The word “Collateral” means the following described property of Grantor, whether now owned or hereafter acquired, whether now existing or hereafter arising, and wherever located:

All Inventory, accounts and equipment, together with the following specifically described property: See Exhibit A and B attached hereto and made a part hereof

In addition, the word “Collateral” also includes all the following, whether now owned or hereafter acquired, whether now existing or hereafter arising, and wherever located:

(A) All attachments, accessions, accessories, tools, parts, supplies, increases, and additions to and all replacements of and substitutions for any property described above.

(B) All products and produce of any of the property described in this Collateral section.

(C) All accounts, general intangibles, instruments, rents, monies, payments, and all other rights, arising out of a sale, lease, or other disposition of any of the property described in this Collateral section.

(D) All proceeds (including insurance proceeds) from the sale, destruction, loss, or other disposition of any of the property described in this Collateral section.

(E) All records and data relating to any of the property described in this Collateral section, whether in the form of a writing, photograph, microfilm, microfiche, or electronic media, together with all of Grantor’s right, title, and interest in and to all computer software required to utilize, create, maintain, and process any such records or data on electronic media.

Event of Default. The words “Event of Default” mean and include without limitation any of the Events of Default set forth below in the section titled “Events of Default”.

Grantor. The word “Grantor” means SYNERGETICS, INC., a Missouri Corporation, its successors and assigns.

Guarantor. The word “Guarantor” means and includes without limitation each and all of the guarantors, sureties, and accommodation parties in connection with the Indebtedness.

Indebtedness. The word “Indebtedness” means the indebtedness evidenced by the Note, including all principal and interest together with all other indebtedness and costs and expenses for which Grantor is responsible under this Agreement or under any of the Related Documents. In addition, the word “Indebtedness” includes all other obligations, debts and liabilities, plus interest thereon, of Grantor, or any one or more of them, to Lender, as well as all claims by Lender against Grantor, or any one or more of them, whether existing now or later; whether they are voluntary or involuntary, due or not due, direct or indirect, absolute or contingent, liquidated or unliquidated; whether Grantor may be liable individually or jointly with others; whether Grantor may be obligated as guarantor, surety, accommodations party or otherwise; whether recovery upon such Indebtedness may be or hereafter may become barred by any statute of limitations; and whether such indebtedness may be or hereafter may become otherwise unenforceable.

Lender. The word “Lender” means Union Planters Bank N.A., its successors and assigns.

Note. The word “Note” means the note or credit agreement dated March 10, 2000, in the principal amount of $1,250,000.00 from SYNERGETICS, INC., a Missouri Corporation to Lender, together with all renewals of, extensions of, modifications of, refinancings of, consolidations of, and substitutions for the note or credit agreement.

Related Documents. The words “Related Documents” mean and include without limitation all promissory notes, credit agreements, loan agreements, environmental agreements, guaranties, security agreements, mortgages, deeds of trust, and all other instruments, agreements and documents, whether now or hereafter existing, executed in connection with the Indebtedness.

RIGHT OF SETOFF. Grantor hereby grants Lender a contractual security interest in and hereby assigns, conveys, delivers, pledges, and transfers all of Grantor’s right, title and interest in and to Grantor’s accounts with Lender (whether checking, savings, or some other account), including all accounts held jointly with someone else and all accounts Grantor may open in the future, excluding, however, all IRA and Keogh accounts, and all trust accounts for which the grant of a security interest would be prohibited by law, Grantor authorizes Lender, to the extent permitted by applicable law, to charge or setoff all Indebtedness against any and all such accounts.

OBLIGATIONS OF GRANTOR. Grantor warrants and covenants to Lender as follows:

Perfection of Security Interest. Grantor agrees to execute financing statements and to take whatever other actions are requested by Lender to perfect and continue Lender’s security interest in the Collateral. Upon request of Lender, Grantor will deliver to Lender any and all of the documents evidencing or constituting the Collateral, and Grantor will note Lender’s interest upon any and all chattel paper if not delivered to Lender for possession by Lender.

Grantor hereby appoints Lender as its irrevocable attorney-in-fact for the purpose of executing any documents necessary to perfect or to continue the security interest granted in this Agreement. Lender may at any time, without further authorization from Grantor, file a carbon, photographic or other reproduction of any financing statement or of this Agreement for use as a financing statement. Grantor will reimburse Lender for all its expenses for the perfection and the continuation of the perfection of Lender’s security interest of the collateral. Grantor promptly will notify Lender before any change in Grantor’s name including any change to the assumed business names of Grantor. This is a continuing Security Agreement and will continue in effect even though all or any part of the indebtedness is paid in full and even though for a period of time Grantor may not be indebted to Lender.

No Violation. The execution and delivery of this Agreement will not violate any law or agreement governing Grantor or to which Grantor is a party, and its certificate or articles of incorporation and bylaws do not prohibit any term or condition of this Agreement.

Enforceability of Collateral. To the extent the Collateral consists of accounts, chattel paper, or general intangibles, the Collateral is enforceable in accordance with its terms, is genuine, and complies with all applicable laws and concerning form, content and manner of preparation and execution, and all persons appearing to be obligated on the Collateral have

authority and capacity to contract and are in fact obligated as they appear to be on the Collateral. At the time any account becomes subject to a security interest in favor of Lender, the account shall be a good and valid account representing an undisputed, bona fide indebtedness incurred by the account debtor, for merchandise held subject to delivery instructions or theretofore shipped or delivered pursuant to a contract of sale, or a service theretofore performed by Grantor with or for the account debtor, there shall be no setoffs or counterclaims against any such account; and no Agreement under which any deductions or discounts may be claimed shall have been made with the account debtor except those disclosed to Lender in writing.

Location of the Collateral. Grantor, upon request of Lender, will deliver to Lender in form satisfactory to Lender a schedule of real properties and Collateral locations relating to Grantor’s operations, including without limitation the following: (a) all real property owned or being purchased by Grantor; (b) all real property being rented or leased by Grantor; (c) all storage facilities owned, rented, leased or being used by Grantor; and (d) all other properties where Collateral is or may be located. Except in the ordinary course of business, Grantor shall not remove the Collateral from its existing locations without the prior written consent of Lender.

Removal of the Collateral. Grantor shall keep the Collateral (or to the extent the Collateral consists of intangible property such as accounts, the records concerning the Collateral) at Grantor’s address shown above, or at such other locations as are acceptable to Lender. Except in the ordinary course of its business, including the sale of inventory, Grantor shall not remove the Collateral from its existing location without the prior written consent of Lender. To the extent that the Collateral consists of vehicles, or other titled property, Grantor shall not take or permit any action which would require application for certificates of title for the vehicles outside the State of Missouri, without the prior written consent of Lender.

Transactions Involving Collateral. Except for inventory sold or accounts collected in the ordinary course of Grantor’s business, Grantor shall not sell, offer to sell, or otherwise transfer or dispose of the Collateral. While Grantor is not in default under this Agreement, Grantor may sell inventory, but only in the ordinary course of its business and only to buyers in the ordinary course of business. A sale in the ordinary course of Grantor’s business does not include a transfer in partial or total satisfaction of a debt or any bulk sale. Grantor shall not pledge, mortgage, encumber or otherwise permit the Collateral to be subject to any lien, security interest, encumbrance, or charge, other than the security interest provided for in this Agreement, without the prior written consent of Lender. This includes security interests even if junior in right to the security interests granted under this Agreement. Unless waived by Lender, all proceeds from any disposition of the Collateral (for whatever reason) shall be held in trust for Lender and shall not be commingled with any other funds; provided however, this requirement shall not constitute consent by Lender to any sale or other disposition. Upon receipt, Grantor shall immediately deliver any such proceeds to Lender.

Title. Grantor represents and warrants to Lender that it holds good and marketable title to the Collateral, free and clear of all liens and encumbrances except for the lien of this Agreement. No financing statement covering any of the Collateral is on file in any public office other than those which reflect the security interest created by this Agreement or to which Lender has specifically consented. Grantor shall defend Lender’s rights in the Collateral against the claims and demands of all other persons.

Collateral Schedules and Locations. As often as Lender shall require, and insofar as the Collateral consists of accounts, Grantor shall deliver to Lender schedules of such Collateral, including such information as Lender may require, including without limitations names and addresses of account debtors and agings of accounts. Insofar as the Collateral consists of inventory and equipment, Grantor shall deliver to Lender, as often as Lender shall require, such lists, descriptions, and designations of such Collateral as Lender may require to identify the nature, extent, and location of such Collateral. Such information shall be submitted for Grantor and each of its subsidiaries or related companies.

Maintenance and Inspection of Collateral. Grantor shall maintain all tangible Collateral in good condition and repair. Grantor will not commit or permit damage to or destruction of the Collateral or any part of the Collateral. Lender and its designated representatives and agents shall have the right at all reasonable times to examine, inspect and audit the Collateral wherever located. Grantor shall immediately notify Lender of all cases involving the return, rejection, repossession, loss or damage of or to any Collateral; of any request for credit or adjustment or of any other dispute arising with respect to the Collateral; and generally of all happenings and events affecting the Collateral or the value or the amount of the Collateral.

Taxes, Assessments and Liens. Grantor will pay when due all taxes, assessments and liens upon the Collateral, its use or operation, upon this Agreement, upon any promissory note or notes evidencing the Indebtedness, or upon any of the other Related Documents. Grantor may withhold any such payment or may elect to contest any lien if Grantor is in good faith conducting an appropriate proceeding to contest the obligation to pay and so long as Lender’s interest in the Collateral is not jeopardized in Lender’s sole opinion. If the Collateral is subjected to a lien which is not discharged within fifteen (15) days, Grantor shall deposit with Lender cash, a sufficient corporate surety bond or other security satisfactory to Lender in an amount adequate to provide for the discharge of the lien plus any interest, costs, attorneys’ fees or other

charges that could accrue as a result of foreclosure or sale of the Collateral. In any contest Grantor shall defend itself and Lender and shall satisfy any final adverse judgment before enforcement against the Collateral. Grantor shall name Lender as an additional obligee under any surety bond furnished in the contest proceedings.

Compliance with Governmental Requirements. Grantor shall comply promptly with all laws, ordinances, rules and regulations of all governmental authorities, now or hereafter in effect, applicable to the ownership, production, disposition, or use of the Collateral. Grantor may contest in good faith any such law, ordinance or regulation and withhold compliance during any proceeding, including appropriate appeals, so long as Lender’s interest in the Collateral, in Lender’s opinion, is not jeopardized.

Hazardous Substances. Grantor represents and warrants that the Collateral never has been, and never will be so long as this Agreement remains a lien on the Collateral, used for the generation, manufacture, storage, transportation, treatment, disposal, release or threatened release of any hazardous waste or substance, as those terms are defined in the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended, 42 U.S.C. Section 9601, et seq. (“CERCLA”), the Superfund Amendments and Reauthorization Act of 1986, Pub. L. No. 99-499 (“SARA”), the Hazardous Materials Transportation Act, 49 U.S.C. Section 1601, et seq., the Resource Conservation and Recovery Act, 42 U.S.C. Section 6901, et seq., or other applicable state or Federal laws, rules, or regulations adopted pursuant to any of the foregoing. The terms “hazardous waste” and “hazardous substance” shall also include, without limitation, petroleum and petroleum by-products or any fraction thereof and asbestos. The representations and warranties contained herein are based on Grantor’s due diligence in investigating the Collateral for hazardous wastes and substances. Grantor hereby (a) releases and waives any future claims against Lender for indemnity or contribution in the event Grantor becomes liable for cleanup or other costs under such laws, and (b) agrees to indemnify and hold harmless Lender against any and all claims and losses resulting from a breach of this provision of this Agreement. This obligation to indemnify shall survive the payment of the Indebtedness and the satisfaction of this Agreement.

Maintenance of Casualty Insurance. Grantor shall procure and maintain all risks insurance, including without limitation fire, theft and liability coverage together with such other insurance as Lender may require with respect to the Collateral, in form, amounts, coverages and basis reasonably acceptable to Lender and issued by a company or companies reasonably acceptable to Lender. Grantor, upon request of Lender, will deliver to Lender from time to time the policies or certificates of insurance in form satisfactory to Lender, including stipulations that coverages will not be cancelled or diminished without at least thirty (30) days’ prior written notice to Lender and not including any disclaimer of the insurer’s liability for failure to give such a notice. Each insurance policy also shall include an endorsement providing that