Patent ID: 7275825

Claim:
An eye refractive power measurement apparatus for measuring eye refractive power of an eye of an examinee, the apparatus comprising: a measurement optical system including a projection optical system having a light source, which projects spot-shaped measurement light onto a fundus of the eye, and a photo-receiving optical system having an optical axis, a photodetector arranged on the optical axis, a ring-shaped aperture having the optical axis as its center, which is arranged at a position conjugate with a pupil of the eye, and passes the light reflected from the fundus via a peripheral pupillary portion of the eye, an image-forming optical member arranged on the optical axis, by which the reflection light from the fundus via the peripheral pupillary portion and the ring-shaped aperture forms a ring-shaped image on the photodetector, and a diaphragm having the optical axis as its center, which is arranged at a position conjugate with the fundus and on a side of the eye relative to the image-forming optical member; and a calculation part which obtains the eye refractive power based on an output from the photodetector, wherein the diaphragm is set to have a size such that a projection region by the diaphragm through the image-forming optical member on the photodetector overlaps the optical axis only within a predetermined amount, and such that the reflection light forms the image within the projection region by the diaphragm in projecting the measurement light onto a myopic eye with the measurable highest diopter.