A loss of vision for one-half of the visual field of either one or both eyes. A loss of vision for one-half of the visual field of either one or both eyes, due to a lesion of the central optic tract.
A clinical phenomenon which seems to express a severe form of automatic sidewards orienting of attention is that of "magnetic gaze attraction" described by Cohn (1972) in patients with homonymous hemianopia, and considered as an "oculomotor analog of extinction" (Friedland & Weinstein, 1977). This phenomenon, which is usually observed while assessing the visual field of a patient with the confrontation technique, involves a tendency to spontaneously orient the gaze toward the side ipsilateral to the brain lesion as soon as the examiner stretches out her/his arms and prior to the actual administration of the stimuli.