Reversible Charles Bonnet syndrome secondary to upper lid ptosis.

Complex visual hallucinations can occur in visually impaired individuals with no underlying psychiatric disorder. This phenomenon is known as Charles Bonnet syndrome (CBS). It is more common in elderly patients who are suffering from impaired vision due to ocular or neurological disease processes, resulting in sensory deprivation. We report a case of CBS in an elderly female with marked ptosis, which was exacerbated following a knee replacement surgery under general anaesthesia. Her CBS symptoms persisted until surgical correction of the ptosis, with a rapid and dramatic resolution of her hallucinations. Although CBS is typically a chronic condition, unusually in this case it was acute and reversible.