Any state employee who opted for membership in the teachers’ retirement system pursuant to chapter 167a and who retires under the provisions of said chapter shall be compensated, effective as of the date of his date of retirement, at the rate of one-fourth of such employee’s salary for sick leave accrued to his credit as of his last day on the active payroll, up to a maximum payment equivalent to sixty days’ pay. Such payment for accumulated sick leave shall not be included in computing retirement income and shall be charged by the State Comptroller to the department, agency or institution in which the employee worked.