Charles Bonnet described a type of visual hallucination that occurs in the elderly with eye problems.
Clinical features:
(1) The typical patient is elderly (age > 64 years) with bilateral visual impairment (often age-related macular degeneration but it can occur with lesions anywhere in the visual system)
(2) The patient has recurrent episodes of complex visual hallucinations.
(3) The patient is cognitively intact without a mental disorder.
(4) The patient eventually is aware that the visions are unreal.
Risk factors:
(1) social isolation
(2) lower cognitive function
(3) history of stroke
(4) poor lighting
Many patients are afraid to mention the hallucinations since they do not want to be considered crazy. It is often necessary to specifically query a patient with risk factors about visual hallucinations.
Affected patients may subsequently have a higher rate of dementia.
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