An ophthalmologic apparatus measures a dimension of an eye to be examined. The ophthalmologic apparatus includes a light source, an incidence member, an acquisition unit, and a display unit. The incidence member causes light from the light source to be incident on a plurality of different positions in the eye to be examined The acquisition unit 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. The display unit displays the acquired two-dimensional tomographic image.