Patent ID: 9480396
Filing Date: 2016-11-01
CPC Classification: A61B

Claim Text:
1. An ophthalmic measurement apparatus comprising: a projection optical system configured to project a pattern target toward a cornea of a subject eye; an imaging optical system provided with an imaging device configured to capture an image of the subject eye, the image including a second Purkinje image, which is a target image formed due to the pattern target being reflected from a posterior corneal surface of the subject eye; a processor connected to the imaging device; and a memory storing computer readable instructions, when executed by the processor, causing the processor to function as: a detecting unit configured to detect the second Purkinje image from the image captured by the imaging device; an acquiring unit configured to acquire posterior corneal surface information related to the posterior corneal surface of the subject eye based on the second Purkinje image detected by the detecting unit; wherein the projection optical system is configured to selectively project one of a plurality of pattern targets on cornea to have an asymmetric shape with respect to a center of the cornea; the processor controls the projection optical system to selectively project one of the pattern targets before performing detection of the second Purkinje image; and the processor detects the second Purkinje image from an upright reflected image of the selectively projected asymmetric pattern target.