An apparatus and a method for optical measurement of an internal contour of a spectacle frame are disclosed. The apparatus contains an optical unit, which is configured to capture light reflected from an illuminated section of the inner contour of the spectacle frame. The optical unit is insertable into the inner contour of the spectacle frame and, when inserted as intended, is rotatable relative to the spectacle frame. The optical unit contains at least one light source, an objective, and at least one optical sensor, wherein the light source is configured to generate a light section, wherein at least one section of the inner contour is illuminable by the light section, wherein the objective is configured to image the illuminated section of the inner contour onto the optical sensor, and wherein the optical sensor is configured to capture the light reflected by the illuminated section of the inner contour.