1. A method of controlling a scanning light measurement apparatus to produce images of an area of an eye, wherein the apparatus scans light across the area, collects light from the eye, divides the light collected from the eye into a first portion of light and a second portion of light, generates first detection data that is representative of the first portion of the collected light, and generates second detection data that is representative of the second portion of collect light, the method comprising: receiving the first detection data and the second detection data; constructing a first image based on the first detection data from a first area of the eye obtained by the apparatus during a first period of time, wherein a length of time of the first period of time is a time for one scan of the first area; constructing a second image based on the second detection data from the first area of the eye obtained by the apparatus during the first period of time; selecting the first image or the second image as a position detection image; estimating a change in position of the first area during the first period of time based on the position detection image; sending instructions to the apparatus to adjust an imaging area based on the estimated change in position of the first area.