ICharles Bonnet was French and born in 1720 – he died in 1793 he was a naturalist and philosophical writer, and was born in Geneva to a French family driven into the region by the religious persecution in the 16th century.

In 1760 he described a condition now called Charles Bonnet Syndrome in which vivid, complex visual hallucinations (fictive visual percepts) occur in psychologically normal people. He documented it in his 87-year-old grandfather who was nearly blind from cataracts in both eyes but perceived men, women, birds, carriages, buildings, tapestries and scaffolding patterns. Most people affected are elderly with visual impairments, however, the phenomenon does not occur only in the elderly or in those with visual impairments; it can also be caused by damage elsewhere in their optic pathway or brain.

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