((a)) The Surgeon General is authorized to provide at institutions, hospitals, and station of the Service medical, surgical, and hospital services and supplies for persons entitled to treatment under subchapter I of Chapter 81 of title 5 and extensions thereof. The Surgeon General may also provide for making medical examinations of—

((1)) employees of the Federal Government for retirement purposes;

((2)) employees in the Federal classified service, and applicants for appointment, as requested by the Director of the Office of Personnel Management for the purpose of promoting health and efficiency;

((3)) seamen for purposes of qualifying for certificates of service; and

((4)) employees eligible for benefits under the Longshore and Harbor Workers’ Compensation Act, as amended [ et seq.], as requested by any deputy commissioner thereunder.

((b)) The Secretary is authorized to provide medical, surgical, and dental treatment and hospitalization and optometric care for Federal employees (as defined in ) and their dependents at remote medical facilities of the Public Health Service where such care and treatment are not otherwise available. Such employees and their dependents who are not entitled to this care and treatment under any other provision of law shall be charged for it at rates established by the Secretary to reflect the reasonable cost of providing the care and treatment. Any payments pursuant to the preceding sentence shall be credited to the applicable appropriation to the Public Health Service for the year in which such payments are received.