VISUAL HALLUCINATIONS

Hallucinations may be defined as perceptions that occur in the absence of a corresponding stimulus. They can involve any of the five senses, hence visual, auditory, tactile, gustatory and olfactory hallucinatio ns. By contrast, illusions depend upon a misinterpretation of an exter nal stimulus. In this review we outline the causes, and describe the c haracteristics of various hallucinatory states. This should help in th e assessment of a patient presenting with visual hallucinations.