(a) As used in this Code section, the term "beneficiary" shall have the meaning specified in paragraph (7) of Code Section 47-3-1 and shall also mean:

(1) Any retired teacher who retired pursuant to any county, municipal, or local board of education retirement or pension system;

(2) The surviving spouse of any retired teacher who retired pursuant to a county, municipal, or local board of education retirement or pension system if such surviving spouse is eligible to receive and is receiving a monthly benefit pursuant to the local retirement or pension system; and

(3) The surviving spouse of a teacher who was a member of a county, municipal, or local board of education retirement or pension system and who died prior to retirement if such surviving spouse is eligible to receive and is receiving a monthly benefit pursuant to the local retirement or pension system.

(b) Effective July 1, 1986, the monthly retirement benefit of each beneficiary who was receiving a benefit on July 1, 1981, shall be increased by:

(1) One dollar for each full year of creditable service which the beneficiary had at the time of retirement; plus

(2) One dollar for each full year which has elapsed from the date of retirement until July 1, 1981.

(c) When the postretirement benefit adjustment provided by this Code section has been granted, there shall be no further postretirement benefit adjustments pursuant to the authority of this Code section.