Exhibit
10.68




NOTE
EXTENSION AGREEMENT




This
Note Extension Agreement (this "Extension Agreement"), by and between Invisa,
Inc., a Nevada corporation, having a business at 1800 2nd
Street, Suite 965, Sarasota, Florida 34236 (the “Borrower”), and Centurian
Investors, Inc., a Delaware corporation, having an address at 1800 2nd
Street Suite 970, Sarasota, Florida 34236 (the “Lender”) is entered into as of
this 17th day of March, 2010 and shall be effective as of the date hereof (the
“Effective Date”).





RECITALS:





WHEREAS, Borrower is indebted to
Lender pursuant to that certain Promissory Note, dated February 28, 2007, in the
principal amount of up to One Hundred Fifty Thousand ($150,000.00) (the
“Note”),





WHEREAS, the Note is secured by (a)
an aggregate of Twenty Million (20,000,000) shares of common stock of Borrower
and (b) a first priority lien on all of the assets of Borrower as more
specifically described in the Note and that certain General Security Agreement,
dated February 28, 2007 (the “Security Agreement” the Notes and the Security
Agreement, together with all documents executed in connection therewith being
hereinafter referred to collectively as the “Loan Documents”); and





WHEREAS, the outstanding principal
balance, together with accrued and unpaid interest, of the Note was due and
payable on August 28, 2007; and





WHEREAS, Lender has periodically
agreed to forebear with respect to certain provisions of the Notes;
and





WHEREAS, Borrower has requested and
Lender agreed to extend the maturity date of the Note, upon the terms and
subject to the provisions set forth herein.





NOW THEREFORE, for ten ($10.00)
Dollars, and other good and valuable consideration, the receipt and sufficiency
of which is hereby acknowledged, the parties hereto agree as
follows:





1.              Terms
used herein which are defined in the Loan Documents shall have the same meanings
when used herein unless otherwise provided herein.





2.              The
Note is hereby amended to extend the Maturity Date of the Note from August 28,
2007 to March 1, 2012.





3.              Lender
shall attach an executed copy of this Amendment to the original Note and all
references hereafter to the Note shall be as amended hereby.





4.              No
right of Lender with respect to the loan evidenced by the Loan Documents or any
agreement, security agreement, financing statements or other documents, executed
or delivered in connection  therewith are or will be in any manner,
released, destroyed, diminished or otherwise adversely affected by this
Agreement, except as expressly provided herein.




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5.              Borrower
understands and agrees that the remaining provisions of the Note shall remain in
full force and effect without any changes or modification except as expressly
stated herein.





6.              The
provisions set forth herein are limited precisely as written and shall not be
deemed to (a) be a consent to, or waiver or modification of, any other term or
condition of the Loan Documents, or (b) except as expressly set forth herein,
prejudice any right or rights which the Lender may now have or may have in the
future under or in connection with the Loan Documents or any of the other
documents referred to therein. Except as expressly modified hereby or by express
written amendments thereof, the terms and provisions of the Loan Documents or
any other documents or instruments executed in connection with any of the
foregoing are and shall remain in full force and effect. In the event of a
conflict between this Agreement and any of the foregoing documents, the terms of
this Agreement shall be controlling. The representations and warranties made in
each Loan Document are true and correct in all material respects on and as of
the date of this Agreement.





7.              None
of the provisions of this Agreement shall inure to the benefit of Borrower or
any person other than Lender. Consequently, Borrower shall not be, and no person
other than the Lender shall be, entitled to rely upon or raise a claim or
defense, in any manner whatsoever, the failure of Lender to comply with the
provisions of this Agreement.  Lender shall not incur
any liability to Borrower or any other person for any act or
omission  whatsoever.





8.              This
Agreement and the documents referred to herein represent the entire
understanding of the parties hereto regarding the subject matter hereof and
supersede all prior and contemporaneous oral and written agreements of the
parties hereto with respect to the subject matter hereof.





9.              This
Agreement may be executed in any number of counterparts and by different parties
on separate counterparts and all of such counterparts shall together constitute
one and the same instrument. Complete sets of counterparts shall be lodged with
the Borrower and the Lender.





IN WITNESS WHEREOF, this Agreement is
executed as of the date first written above and shall be effective as of the
Effective Date.









INVISA,
      INC.
            CENTURIAN
      INVESTORS, INC.Name:
            Name:Title:
            Title:




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