A psychophysical technique for measuring cone photopigment bleaching.

A new, clinically applicable test has been developed to measure the bleaching of the foveal cone photopigments. This noninvasive test is called steady-state color matching. Steady-state color matching is based on the dependence of a color match on the optical density of the cone photopigments. By measuring the color match as a function of retinal illuminance, it is possible to compute the optical density of the cone photopigments at each illuminance. Thus, abnormalities of photopigment bleaching can be detected. This study demonstrates that the technique is readily performed by a clinical population. Patients with central serous retinopathy and retinitis pigmentosa are shown to have low effective optical densities.