Charles Bonnet's Syndrome

Charles Bonnet's syndrome is a condition of the aged, similar to hypnagogic imagery and Lilliputian hallucination Opens in new window, in which individuals, experience extremely vivid visual hallucinations Opens in new window.

The syndrome occurs persistently and repetitively without any delusions Opens in new window or hallucinations Opens in new window in any other modality.

The hallucinations are exclusively visual, may occur at the close of day, are recognized as hallucinatory, and have a vivid, complex, often miniature, mobile character.

Although more common in the elderly, Charles Bonnet’s syndrome can occur at any age and is usually associated with central or peripheral reduction in vision. Episodes may last from days to years, with images of people, animals, buildings and scenery being most frequently reported, the images being static, moving in the visual field or animated.

The phantom visual images may be microscopic, macroscopic or normal in size, and with illusory distortion. Of interest is that that the position of the observer plays a role; the hallucination may change in size or character when the subject reaches out to touch it.

The hallucinations may be lateralized, presumably to the side of a visual field defect. Some authors have claimed that the disorder is related to cataracts or other ocular pathology, though there are sufficient cases with normal vision to disconfirm this view.

In most cases of Charles Bonnet’s syndrome, and in musical hallucinosis in the deaf, to which it has been likened, there is no demonstrable brain pathology (Fuchs and Lauter, 1992). The features of this syndrome have been considered by Podoll et al. (1990) to be as follows:

• Elderly persons with normal consciousness experience visual hallucinations.
• None of the following are present: delirium   Opens in new window, dementia   Opens in new window, organic affective or delusional syndromes, psychosis, intoxication or neurological disorder with lesions of the central visual cortex.
• There is reduced vision, resulting from eye disease in most cases.