(a) A living will executed on or after March 28, 1986, shall be effective from the date of execution thereof unless revoked in a manner prescribed in Code Section 31-32-5.

(b) A living will executed prior to March 28, 1986, in the form specified by prior law shall be effective for a period of seven years from the date of execution thereof, except that, if the declarant crosses through or otherwise marks over the paragraph of such a living will relating to the seven-year period of effectiveness of the living will so as to indicate an intention to defeat the operation of such paragraph, and if the declarant signs or initials the living will in the area of the stricken paragraph, then the living will shall continue in effect until and unless revoked in a manner prescribed in Code Section 31-32-5.