Relative afferent pupillary defect in optic tract hemianopias.

We saw four patients with optic tract lesions and complete homonymous hemianopia. In each patient, the visual acuity was good in both eyes. All four patients had a relative afferent pupillary defect in the eye with the temporal field loss. This pupillary sign is to be expected in all such cases and may serve to differentiate acute optic tract lesions from acute geniculostriate lesions when the characteristic midnasal pallor of the nerve head has not had time to develop.