1. An ophthalmologic apparatus that measures, by light interference, a dimension of an eye to be examined, the ophthalmologic apparatus comprising: a light source; an incidence member that causes light from the light source to be incident on a plurality of different positions in the eye to be examined; an acquisition unit that acquires a two-dimensional tomographic image of an interior of the eye to be examined on the basis of a plurality of interference signals acquired as a result of the incidence member causing the incidence of light on the plurality of different positions; and a display unit that displays the acquired two-dimensional tomographic image.