Abstract: In a process for fitting a contact lens to a human eye, the geometry of the eyeball and the back surface geometry of the lens, and the required optical corrections for the distant and near vision of the eye to be corrected are determined. The measurement for fitting the contact lens takes place with a measuring lens that enables determination of relative pupil motion with respect to a reference system on or near the eye on changing from far vision to near vision. The measuring lens to be used for this measurement process has a substantially spherical lens body that has a substantially convex outer surface and a substantially concave inner surface. This measuring lens preferably serves for fitting multifocal contact lenses. To facilitate the measuring process, arrangements for determining the relative movement of a human pupil with respect to the surface of the measuring lens is provided on the measuring lens.