Overview
Also known as visual release hallucinations, Charles Bonnet syndrome (CBS) describes the experience of visual hallucinations in a person that has experienced a partial or complete loss of vision. The hallucinations are always visual, usually temporary, and are unrelated to any mental or behavioural disorders. Its aetiology is unknown.
Epidemiology
- Affects anyone with a sharp decline in vision, particularly people with macular degeneration, cataracts, and diabetic retinopathy
- More common in elderly people but has been seen in children
Risk Factors
- Increased age
- Visual impairment
- Diabetic patients
- History of macular degeneration
- History of cataracts
Presentation
Patients experience exclusively visual hallucinations, typically on a background of visual loss. It is always essential to rule out neuropsychiatric conditions. Some features are:
- They may see simple patterns
- They may see figures and faces which may be recognisable to the patient
- They may see text or letters but cannot read them when they try to
- The hallucinations are always outside of the body
- They have no personal meaning to the patient
- Hallucinations last from seconds to hours
- Symptoms tend to worsen in dim lighting conditions
- Patients generally do not have features of neuropsychiatric disorders (e.g. dementia)
