Patent ID: 11944383
Assignee: CARL ZEISS VISION INTERNATIONAL GMBH
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 10:
11. An apparatus for determining a refractive error of an eye, the apparatus comprising:
a camera configured to capture an image of light from the eye; and
an optical power changing device configured to vary an optical power of a light path from the eye to the camera,
wherein the apparatus includes a computing device which is configured to calculate the refractive error of the eye based on a series of images of light from the eye captured by the camera with varying optical power using the series of images as at least approximate point spread functions, by determining an optical power where the point spread function is sharpest for at least three meridians, and calculate the refractive error based on the optical powers where the point spread function is sharpest determined for the at least three meridians, and
wherein, for determining the optical powers where the point spread function is sharpest, the computing device is configured to calculate modulation transfer function areas for each of the at least three meridians, and to determine the optical power where the point spread function is sharpest as an optical power at a maximum modulation transfer function area for the respective meridian.