Visual hallucinations in the works of Oliver Sacks

Hallucinations are one of the most bizarre experiences in several diseases. They appear in mental diseases as well as in physical illnesses and may be the consequence of the usage of drugs of abuse. However, a detailed analysis of how patients feel under hallucinations caused by different diseases is uncommon. This article analyses how visual hallucinations are considered in the works of the neurologist and writer Oliver Sacks, with special attention to his book Hallucinations. Hallucinations have been under consideration by culture, religion and arts, which has led to multiple interpretations. Sacks's interest in perception of sensations led him to work on the analysis of hallucinations, given the limited knowledge on the topic. References to hallucinations appeared in several of his books like Migraine, Awakenings and A leg to stand on. In Musicophilia Sacks approached the auditory hallucinations and in Hallucinations he considered them in depth. In the latter work, Sacks analyses especially those present in Charles Bonnet syndrome, in situations of sensory deprivation, in patients with epilesy, those present during treatment with levodopa and those caused by drug of abuse. Hallucinations is one of Sacks's books with greater neuroophthalmological content. The descriptions of the hallucinations of his patients or those experienced by himself, as well as the reflective analysis on the world of perception make this book one of the most fascinating works of Oliver Sacks.