Over-refraction provides a powerful method for the refractive examination of the aphakic or highly ametropic patient. Nevertheless, in the past, practical difficulties that attend mathematical or graphical combination of over-refraction and original spherocylinders have tended to limit the clinical use of over-refraction methods. Programmable calculators, now available inexpensively, render over-refraction clinically practical. An over-refraction program for the Texas Instruments TI-59 Card-Programmable Calculator is presented. Program running time, exclusive of data entry and readout, is under 15 sec.