Charles Bonnet's syndrome: not only a condition of the elderly

To investigate whether the experience of visual hallucinations, namely Charles Bonnet's syndrome, in psychologically healthy people is a phenomenon solely of elderly, visually impaired people.

In a prospective controlled study, four groups of subjects (total 324) were formed: age ≤40 years, no visual impairment; age ≤40 years, visually impaired; age >40 years, no visual impairment; age >40 years, visually impaired. Visual impairment was defined as best-corrected visual acuity ≤0.3 (Snellen) in the better-seeing eye. Each group consisted of 81 subjects. Visual hallucinations were defined as complex visual perceptions. After ruling out psychiatric causes for visual hallucinations or medication related to the experience of visual hallucinations, affected subjects underwent a detailed interview about their visual hallucinations.

The prevalence of visual hallucinations among young subjects with visual impairment was 4.9 %; among the elderly visually impaired subjects, it was 6.2 %. The difference was not statistically significant. No subject without visual impairment experienced visual hallucinations.

Charles Bonnet's syndrome is not limited to elderly people suffering from visual impairment, though there tends to be a higher prevalence of visual hallucinations in this group.