Acute zonal occult outer retinopathy (AZOOR) is a rare unilateral or bilateral disease of unknown etiology characterized by focal degeneration of photoreceptors. A total of 131 cases of AZOOR (205 eyes), including the variant known as acute annular outer retinopathy, have been reported in the English language literature. In this group of predominantly white individuals, average age at presentation was 36.7 years, and the male:female ratio was 1:3.2. The majority of patients complained of the acute onset of a scotoma, which was associated with photopsia. Visual acuity was 20/40 or better in 74% of tested eyes, and fundus examination was unremarkable in 76% of eyes. Blind spot enlargement, with or without other field defects, was observed in 75% of the visual fields examined, and electroretinographic abnormalities were recorded in 99% of patients tested. Typically patients retained good visual acuity, although retinal pigment epithelial disturbances commonly developed over time. It was unusual for visual field loss to continue beyond six months. Various treatments have been attempted in patients with AZOOR--including systemic corticosteroids, other systemic immunosuppressive agents, and different antimicrobials--but none have been proven effective. Copyright © 2011 Elsevier Inc. All rights reserved.