DESCRIPTION: A long term goal of this research program is to understand the action of retinal diseases on visual sensitivity. One aim of the proposal is to test specific hypotheses about the sites and mechanisms of disease action inpatients with glaucoma, diabetic retinopathy, retinitis pigmentosa, and allied retinal diseases. Electrophysiological, primarily ERG recordings, and a variety of psychophysical techniques will be used to probe the different retinal areas (fovea versus peripheral), retinal layers (receptor versus inner retina) and retinal pathways (cone, rod, luminance etc). The electrophysiological and psychophysical data from the patients and normal controls will be analyzed within the context of models of the normal visual system. A second long term goal is to develop models of light adaptation that can predict the adjustment of the normal visual system to ambient light. A specific aim is to continue development of a model of cone system light adaptation and extend this to the rod system. A related long term goal is to develop new techniques for localizing sites and for identifying mechanisms of light adaptation and retinal disease. A specific aim is to explore a new technique for obtaining ERG responses from local retinal regions. This could be especially valuable in assessing retinal function of patients with heterogeneous damage as in retinitis pigmentosa, diabetic retinopathy, and glaucoma.