Visual hallucination

A visual hallucination is a vivid visual experience occurring without corresponding external stimuli in an awake state. These experiences are involuntary and possess a degree of perceived reality sufficient to resemble authentic visual perception. Unlike illusions, which involve the misinterpretation of actual external stimuli, visual hallucinations are entirely independent of external visual input. They may include fully formed images, such as human figures or scenes, angelic figures, or unformed phenomena, like flashes of light or geometric patterns.

Visual hallucinations are not restricted to the transitional states of awakening or falling asleep and are a hallmark of various neurological and psychiatric conditions. They are documented in schizophrenia, toxic encephalopathies, migraines, substance withdrawal syndromes, focal central nervous system lesions, and psychotic mood disorders. Although traditionally linked with organic aetiologies, visual hallucinations occur in approximately 25% to 50% of individuals with schizophrenia. In such cases, they frequently co-occur with auditory hallucinations, though they may also manifest independently.

Approximately one-third of individuals with psychotic disorders experience visual hallucinations. Despite their prevalence, the underlying mechanisms remain poorly understood, which hinders the development of targeted therapeutic approaches.