An apparatus is provided for finding and defining a prescription for prism glasses for Diplopic patients and AMD patients whose Macula and Fovea are damaged enough that the patients have double vision, but, still have relatively good acuity. The apparatus positions lenses in infinitely variable locations horizontally and vertically in front of the patients eyes until the patient indicates that he/she sees the two images fuse. The H-V coordinates of the location of the Optic center of each lens axis in relation to the patients visual axis are decentration dimensions indicated for each eye by the H and V dials on the apparatus and are thus the basis for an accurate prescription for prism lenses.
