Patent attributes
An ophthalmologic apparatus is configured to control an optical scanner so as to perform a scan by measurement light in an intersecting direction which intersects a traveling direction of the measurement light, to specify a scan length based on a detection result of interference light corresponding to the scan, the detection result being acquired by an interference optical system, the scan length being a length of a scan range in the intersecting direction within a characteristic region in an anterior segment of the subject's eye, and to specify a movement amount of the subject's eye based on a reference value of the characteristic region and the scan length.