Anterior ischemic optic neuropathy associated with macrocytic anemia.

A 37-year-old man experienced the acute onset of blurred vision, particularly in the inferior hemifield of his left eye. Neuro-ophthalmic examination showed a left afferent pupillary defect, a left inferior altitudinal visual field deficit, bilateral nerve fiber layer infarcts and hemorrhages, and left optic disc elevation with edema of the nerve fiber bundle. Complete examination and laboratory studies revealed only a severe folate deficiency anemia. This is the first well-documented report of anterior ischemic optic neuropathy associated with anemia in the absence of other systemic abnormalities.