Effective January 1, 1973, blind or partially sighted persons licensed as vending stand operators within the controlled programs of the bureau of blind services are deemed to be employees within the meaning of this act for state retirement purposes only, and except as hereinafter provided are entitled to all the rights and benefits of state employees covered by the provisions of this act. Operators licensed in the vending stand program after January 1, 1973, who meet all the eligibility requirements of the state retirement system shall participate under the provisions of this act. A person covered by this section may receive retirement system service credit for not more than 10 years of service performed before January 1, 1973, providing, that such person pays the state employees' retirement system a contribution equal to that which would have been paid for each year that the blind vending stand operator has been under the state employees' retirement system with a maximum contribution of $416.00 per year. Blindness shall not be deemed a retirable disability under this act for persons covered by this section. The employer shall be deemed to be the Michigan department of social services. The employer cost of retirement shall be funded from moneys appropriated yearly to the department of social services.