Acute visual loss is not an infrequent presenting complaint to the Emergency Department. The history of visual loss, physical examination of the eye, and indicated laboratory evaluation are keys to making the diagnosis. The etiology of nontraumatic visual loss is diverse, involving vascular, anatomic, infectious, autoimmune, toxicologic, and psychogenic causes. Appropriate treatment, as well as the need for timeliness of ophthalmologic consultation, is described.