The afferent pupillary defect as an early manifestation of occult temporal arteritis.

A 76-year-old man had excellent visual acuity and an afferent pupillary defect (Marcus-Gunn pupil) on one side. After several weeks of investigation, a diagnosis of biopsy-proved temporal arteritis was made. I believe that this is the first case of "occult" temporal arteritis with essentially normal vision and with an afferent pupillary defect as the sole original manifestation of the disease.