Subject to regulations of the President, lightkeepers, assistant lightkeepers, and officers and crews of vessels of the former Lighthouse Service, including any such persons who subsequent to June 30, 1939, were involuntarily assigned to other civilian duty in the Coast Guard, who were entitled to medical relief at hospitals and other stations of the Public Health Service prior to July 1, 1944, and who retired under the provisions of section 763 of title 33, shall be entitled to medical, surgical, and dental treatment and hospitalization at hospitals and other stations of the Public Health Service.