Visual hallucinations in Charles Bonnet syndrome

Frank Eperjesi

in Hallucinations

Published on behalf of Oxford University Press

Published in print June 2010 | ISBN: 9780199548590
Published online February 2013 | e-ISBN: 9780191754623 | DOI:
Visual hallucinations in Charles Bonnet syndrome

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Although CBS was first described in 1769, there is still much to be learned about the condition. Accurate diagnosis is critical in order to avoid misdiagnosis and inappropriate intervention (McNamara et al., 1982; Abbott et al., 2007) and although awareness is growing, many medical professionals know little about the condition.

It has been suggested that the typical CBS hallucination occurring in association with AMD (the most common eye condition causing visual impairment) is that of a person, in colour, within the central scotoma, occurring any time of the day, on most days, lasting a few seconds and not generally associated with pleasant or unpleasant feelings and possibly resolving on closing the eyes. Studies show that many people do not report their hallucinations to doctors or optometrists because they believe that they may be thought of as mentally ill. Sufferers invariably do not admit to their hallucinations unless specifically asked. It is therefore important for clinicians to inform those who are susceptible to CBS about the condition, and also to ask direct questions about the appearance of hallucinations if CBS is suspected during a sensitive and sympathetic history taking. Early reassurance is important in patient care, with sympathetic understanding and explanation providing emotional relief. Sympathetic explanation of the benign nature of such hallucinatory experiences is a source of considerable emotional relief. It is sensible to advise all visually impaired people, even those who do not admit hallucinatory experiences, of the possible future occurrence of hallucinations to render them better prepared to deal with such experiences should they arise.

Pharmacotherapy is disappointing as demonstrated by the diverse range of therapeutic agents advocated in this condition (Menon, 2005). A trial of pharmacotherapy may be justified under the guidance of an expert physician or psychiatrist in the context of persistent disturbing hallucinations in a subject refractory to reassurance (Menon, 2005).

It is my view that primary health care practitioners such as optometrists and general medical practitioners should ask about the occurrence of visual hallucinations or warn about their possible onset when they encounter patients who are old and have an eye disease (Melzack, 1989) (particularly AMD as it is a common eye disease in older people) that causes the VA to be reduced to a level where it is 6/24 in the better eye. Those with suspected CBS should initially be referred to a low vision specialist who may be able to reduce or alleviate hallucinatory activity by optimizing visual function, providing reassurance and information, and recommending methods that can help reduce the duration of hallucinatory periods. At the same time, if there is a self-help group in the locality, the patient should be given the opportunity of attending. If this approach fails to have a satisfactory impact on hallucinatory activity then, in those cases where there is an operable ocular condition such as cataract, the patient could be considered for surgery. When optical or surgical intervention is not an appropriate option, then a referral to a specialist for pharmacological therapy can be instigated. Finally, greater awareness of CBS is necessary to avoid inappropriate labelling and treatment for non-existent psychosis.

Chapter.  9831 words. 

Subjects: Psychiatry

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