The unidirectionality of cerebral polyopia.

Polyopia, visual perseveration in space, has been associated with seizure activity, afterimage formation, and the presence of visual field defects. It can be interpreted both as a positive and a negative visual phenomenon. A patient with polyopia associated with the acute onset of hemianopsia is presented. The phenomenon has been investigated objectively with a simple procedure. The polyopia was highly correlated to movement of the eyes into the hemianoptic visual field and to increased contrast but not duration of the stimulus. This type of polyopia could be the result of incomplete visual processing due to poor visuospatial localization in a hemianopic field.