(a) Any judge of a superior court shall be permitted to pay into the fund the amount of 5 percent of the salary paid to such judge by the state and any such judge who makes payment into this fund shall be eligible to retire from office as a senior judge at a salary of two-thirds of the salary now or hereafter paid to judges of the superior courts by the State of Georgia, provided he meets the following conditions:

(1) He is in at least his nineteenth year of service as a judge of the superior courts of this state or has already been in service for 19 years as a judge of the superior courts of this state on March 9, 1945, and has been appointed as a senior judge as provided in Code Section 47-8-40;

(2) He has for a period of 19 years made payments to the fund at the rate specified in this Code section. However, all judges who are over 50 years of age shall be eligible to retire when they have attained the age of 68 years at two-thirds' the salary paid by the state to such judges, provided such judges have served for at least 19 years and have made payments to the fund at the rate therein specified until they reached the age of 68 years, such payments to commence from March 9, 1945, provided that any judge who shall, by virtue of the amendment of this chapter approved February 16, 1950, be made eligible for appointment as a senior judge and who shall not have made payments to the Superior Court Judges Retirement Fund of Georgia at the time of the passage of such amendment shall be required to pay into the fund the amount fixed by this chapter for each of the years that such judge has served as a superior court judge from January 1, 1951, up to and including the year that such judge may be appointed as a senior judge, provided such judge has served at least four years in one complete term or its equivalent number of years in two or more terms as judge of the superior courts. Any superior court judge, in order to qualify under this Code section, who has previously served as district attorney shall have contributed to the District Attorneys Retirement Fund from the date of the enactment of the District Attorneys Retirement Fund or from the time such judge became a district attorney, whichever is the later date. In the event that a judge shall receive credit under this subsection for service as a district attorney, the board of trustees of the District Attorneys Retirement Fund is authorized and directed to transfer the amounts which such judge has contributed to such fund to the Superior Court Judges Retirement Fund of Georgia; and

(3) Any other provisions notwithstanding, any judge of the superior courts who had not made payments to the Superior Court Judges Retirement Fund of Georgia at the time of the passage of the amendment of this chapter, approved February 16, 1950, and who is in his nineteenth year of service as a judge of the superior courts, district attorney, or judge or solicitor of a state, county, or city court or any court of record of the State of Georgia from which an appeal may be taken directly to the Court of Appeals of Georgia, shall make payments as provided by law to the Superior Court Judges Retirement Fund of Georgia from January 1, 1951, to the date of appointment as a senior judge under this chapter, provided that nothing in this subsection shall be construed so as to authorize the refund of any amounts previously paid into the Superior Court Judges Retirement Fund of Georgia. (b) All judges of the superior courts shall be permitted to pay into the fund the amount of 5 percent of the salary paid to such judges by the State of Georgia and any of such judges who have made payment to this fund shall be eligible to retire from office as senior judge at a salary of one-half of the salary now or hereafter paid to judges of the superior court by the State of Georgia, provided he meets either of the following conditions:

(1) He has reached the age of 65 years and has completed ten years of service as a judge of the superior courts of this state, as distinguished from creditable service, and has for the period of his service as such judge made payments to the fund at the rate specified in this subsection and has been appointed as a senior judge of the superior courts, as provided in Code Section 47-8-40; or

(2) He has for a period of ten years made payment to such fund at the rate specified in this subsection and is prevented because of incapacity from continuing his duties as judge of the superior courts and has been appointed as a senior judge, as provided in Code Section 47-8-40, provided that any amount accruing prior to December 11, 1953, may be paid at such times as the board of trustees of the Superior Court Judges Retirement Fund of Georgia may direct.