The Charles Bonnet syndrome and the problem of visual perceptual disorders in the elderly.

The literature, classical and modern, on visual perceptual disturbances in the elderly is reviewed. The utility of the concept of the Charles Bonnet Syndrome, an eponym originally coined to describe visual hallucinations in the elderly in the absence of cognitive impairment and peripheral ophthalmopathy, is challenged, particularly as the syndrome has become progressively enlarged. Three representative cases of elderly patients who have developed different types of visual perceptual disturbances are described. It is proposed to undertake a systematic study of the frequency of such disturbances in the elderly and of what other pathologies, particularly cognitive and visual, may be associated with them.