Charles Bonnet Syndrome: Diagnostic Criteria and Management

Diagnostic Criteria and Epidemiology

Charles Bonnet syndrome (CBS) is characterized by recurrent, vivid visual hallucinations in patients with vision impairment who maintain insight that their perceptions are not real, without other neurological or medical diagnoses explaining the hallucinations, as defined by the American Academy of Ophthalmology 1, 2, 3
The syndrome is defined by four key features: recurrent, vivid visual hallucinations, patient insight that what is seen is not real, no other neurological or medical diagnosis explaining the hallucinations, and some degree of vision loss, according to the American Academy of Ophthalmology 1
CBS affects patients with any level of vision impairment, with a prevalence ranging from 15% to 60% among patients with ophthalmologic disorders, depending on definition and population studied, as reported by the American Academy of Ophthalmology 1
More than 20% of people with vision loss experience these hallucinations, according to the American Academy of Ophthalmology 4

CBS is attributed to a cortical-release phenomenon resulting from lack of afferent visual information, representing a form of "phantom vision" due to deafferentiation of visual association areas in the cerebral cortex, as explained by the American Academy of Ophthalmology 1
A possible link between CBS and cognitive dysfunction is under current research, according to the American Academy of Ophthalmology 1
Hallucinations can occur with various types of vision loss, including reduced visual acuity, contrast sensitivity deficits, visual field loss, and monocular vision loss, as reported by the American Academy of Ophthalmology 1

Educate patients and family/caregivers that phantom vision is common in visually impaired people, and reassure patients that hallucinations do not indicate mental illness, as recommended by the American Academy of Ophthalmology 1
Self-management techniques that may reduce hallucinations include eye movements, changing lighting conditions, and distraction techniques, according to the American Academy of Ophthalmology 1
Transcranial direct-current stimulation (tDCS) has shown promise in reducing hallucination frequency in a small trial, as reported by the American Academy of Ophthalmology 1
Consider psychological therapies and support groups for patients with vision loss, as recommended by the American Academy of Ophthalmology 1

Atypical features that should raise suspicion of diagnoses other than CBS include lack of insight into the unreal nature of images, hallucinations that interact with the patient, associated neurological signs or symptoms, and evolution to include psychotic symptoms, as warned by the American Academy of Ophthalmology 1, 3, 5

Total visual loss is extremely rare in conditions like AMD that may cause CBS, as reported by the American Academy of Ophthalmology 6