[Charles Bonnet's syndrome: clinical insights in a fascinating disease]

Even mentally and cognitively healthy people can experience visual hallucinations. These are called Charles Bonnet's syndrome, named after the Swiss scientist, who first described such perceptions in the 18th century. Usually patients possess insight in the unreality of their visual experiences. The definitions of CBS are not consistent. Visual impairment or blindness is not part of every definition, but often is associated with CBS. Ophthalmologists should be aware of this syndrome, since its prevalence is high among blind or visually impaired people: patients often are reluctant to admit their hallucinatory experiences, because of the fear of being stigmatised. Possibly women are affected more often than men. CBS is well investigated in the elderly, but also young people might experience visual hallucinations. Hallucinatory contents commonly are persons, with varying duration of the hallucinations. Most patients experience more than one hallucinatory episode. CBS is best investigated in patients suffering from AMD. Neuroimaging studies suggest that cerebral abnormalities, mainly in the occipital cortex, might also play a role in the pathogenesis of CBS. Many patients do not require (drug) treatment, since education itself is helpful in most cases. The pathophysiology remains unclear, but there are a couple of theories.