The project is planned to study the effect of human retinal and cortical organization on visual evoked potentials and psychophysical responses to contrast modulated grating patterns. Visual evoked potential analysis will be performed by a new, rigorous mathematical method of nonlinear analysis, which has already been shown in the laboratory to be the most powerful tool in the study of parallel visual pathways. The topography of evoked potential components will be studied in normals and in specifically selected patients. Scalp distribution of VEP kernels in normals and in patients with monocular and binocular visual defects will be compared to discern whether response properties of X and Y ganglion cells of the retina are reflected, in addition to signals of separate neuronal ensembles of the cortex, in the harmonics of the evoked potential. Emphasis will be on studies of patients with glaucoma and localized lesions of the visual pathways. Their in-depth psychophysical and VEP studies will be utilized to develop diagnostic methods which may be of special value for future management of ocular hypertension. The studies will contribute to improved diagnosis and characterization of impaired vision in lesions of the eye and brain. By applying up-to-date technology and sophisticated systems analysis to clinical studies, physiological properties of the human visual pathways will be inferred.