Eight psychophysical tests were used to evaluate visual function in a patient with dense opacities of the cornea and lens. Hue discrimination, dark adaptation and increment thresholds yielded quantitative data on the extent of cone and rod function. After removal of the cataractous lens, visual field size could be determined by kinetic perimetry. With eye pursuit movement, profile and flicker perimetry, some information was also obtained on foveal performance and meridional distribution of visual sensitivity. These measurements were compared with results obtained after implantation of a keratoprosthesis. They show that psychophysical procedures can be useful in establishing the postoperative prognosis in patients with opaque optic media. Such tests, therefore, should be combined with objective methods of examination.