Section 8C. There is hereby created in the registry a medical advisory board, consisting of the commissioner of the department of public health or his designee, who shall serve as chairman thereof, and fifteen members appointed by the registrar and approved by said commissioner, who shall be registered under the laws of the commonwealth as qualified physicians, optometrists or chiropractors, but not more than one of said appointees shall be a chiropractor and not more than one of said appointees shall be an optometrist. The members of the said board except said commissioner, shall serve at the pleasure of the registrar. The registrar may refer to said board for advisory opinions on standards of fitness for applicants for learner's permits or licenses to operate motor vehicles, and, in addition, for advisory opinions on the applications of persons who apply for learner's permits or licenses to operate motor vehicles or whose right to operate has been suspended or revoked, or whenever the registrar has reason to believe that the operation of a motor vehicle by such persons upon any way or in any place to which members of the public have access as invitees or licensees would be a threat to the safety and the welfare of the public because of physical or mental disability. Upon receipt of an application for a medical exemption for the benefit of the owner or operator of a motor vehicle whose vision is determined by the board to be light sensitive or photosensitive, said board shall grant an exemption indicating the need for special window treatment as a medical necessity. The board shall meet at the call of said commissioner at such times and places as he may select, but shall convene at the request of the registrar. Said commissioner shall provide such facilities as he may determine to be necessary or appropriate to the function of the board. Each member of the board shall receive as compensation for his service thereon a sum not to exceed thirty-five dollars for each meeting he attends.