Transient vertical monocular hemianopsia with anomalous retinal artery branching.

A 62-year-old man reported 6 stereotyped attacks of transient loss of vision in the lateral visual field of the right eye and was subsequently found to have right internal carotid artery occlusion. Fundoscopy revealed an anomalous central retinal artery branching whereby a single stem vessel supplied the superior and inferior nasal quadrants of the retina. Circulatory insufficiency in this anomalous stem could explain the occurrence of vertical monocular hemianopsia as an unusual manifestation of ipsilateral carotid artery atherosclerosis.