The long-term objective is to describe and elucidate the photopic abnormalities that occur in a variety of human visual disorders. This objective is pursued in a psychophysical study of patients afflicted with a retinal disease such as retinitis pigmentosa, Stargardt's macular dystrophy, or with a cortical disorder, for example, acquired from a head injury. The principal measurements consist of Stiles' two-color threshold measurements, color matches, and the Westheimer's spatial excitatory-inhibitory areas. We also propose to develop and explore the use of pupillometry as an objective measure of the visual function in clinical patients. The understanding of the functional abnormalities which we expect to accrue can contribute to the development of more sensitive diagnostic methods as well as to a better understanding of the underlying pathology.