[Visual hallucinations in ophthalmological and neurological diseases]

Visual hallucination can be defined as visual sensory perception without external stimulation, or something that a patient sees that other observers in the same environment do not see. The images may be unformed (lights, streaks, flashes) or formed (objects, people, scenes). Clinical experience indicates that, despite the infrequency with which they are mentioned, visual hallucinations commonly occur in patients with ophthalmological and neurological diseases. Content, duration and timing of visual hallucinations relate to their cause and provide useful clinical information. This paper reviews the topical, pathophysiological and clinical aspects of visual hallucinations.