[Charles Bonnet syndrome]

The article reviews the current literature on Charles Bonnet syndrome (CBS), offers specific criteria to define this syndrome, evaluates its prevalence, analyses the possible associated ophthalmic and sociodemographic factors, suggests future work in this area. Despite the recent interest in CBS in contemporary medical literature, a universal definition of this entity has not been fully established yet. The syndrome is usually characterised by presence of vivid and complex visual hallucinations, which are recognised as unreal and occur in the absence of any other psychiatric symptoms. Therefore there are suggestions that the phenomena should be best described by the term 'pseudohallucinations' or 'parahallucinations'. Some researchers suggest that isolated visual hallucinations in older adults may be an indication of early stages of dementia. Contrary to what was considered for a long time, the syndrome seems to occur rather frequently. Recent findings support association of CBS with sensory deprivation and advanced age. CBS should be considered as a diagnosis in patients who complain of hallucinations and who meet the defined diagnostic criteria. There is no proven treatment, but many patients will benefit from reassurance that their hallucinations do not imply mental illness.