Patients with Cerebral Blindness*

Using high resolution perimetry in repeated sessions. we investigated 27 patients with homonymous visual field äefJcts in order to detect islands of vision within the damaged area, and to determine color- and form-recognition abilities within these zones of residual vision. In most Patients we found circumscribed areas within the "blind " field in which the stimulus was detected in about 50Vo of Presentations. Only one patient had an island of vision greater than 5 ' within the defective area. We also found an area of variable performance between the blind and the intact field. Borders of field defects were classified as being: (a) iharp (small transition zone), (b) medium, or (c) fuzzy (scattered deficits). We propose that transition zones are functional representations of partially spared neuronal stnrctures in areas of the brain which are only partially injured