42 C.F.R. § 410.23
Screening for glaucoma: Conditions for and limitations on coverage
(a) Definitions: As used in this section, the following definitions apply:
(1) Direct supervision in the office setting means the optometrist or the ophthalmologist must be present in the office suite and be immediately available to furnish assistance and direction throughout the performance of the procedure. It does not mean the physician must be present in the room when the procedure is performed.
(2) Eligible beneficiary means individuals in the following high risk categories:
(i) Individual with diabetes mellitus.
(ii) Individual with a family history of glaucoma.
(iii) African-Americans age 50 and over.
(iv) Hispanic-Americans age 65 and over.
(3) Screening for glaucoma means the following procedures furnished to an individual for the early detection of glaucoma:
(i) A dilated eye examination with an intraocular pressure measurement.
(ii) A direct ophthalmoscopy examination, or a slit-lamp biomicroscopic examination.
(b) Condition for coverage of screening for glaucoma. Medicare Part B pays for glaucoma screening examinations provided to eligible beneficiaries as described in paragraph (a)(2) of this section if they are furnished by or under the direct supervision in the office setting of an optometrist or ophthalmologist who is legally authorized to perform these services under State law (or the State regulatory mechanism provided by State law) of the State in which the services are furnished, as would otherwise be covered if furnished by a physician or incident to a physician's professional service.
(c) Limitations on coverage of glaucoma screening examinations. (1) Payment may not be made for a glaucoma screening examination that is performed for an individual who is not an eligible beneficiary as described in paragraph (a)(2) of this section.
(2) Payment may be made for a glaucoma screening examination that is performed on an individual who is an eligible beneficiary as described in paragraph (a)(2) of this section, after at least 11 months have passed following the month in which the last glaucoma screening examination was performed.