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SYMPTOMS
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Visual hallucinations in the presence of vision/visual field loss
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SIGNS
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Any ocular disease such as age-related macular degeneration or glaucoma that can cause vision loss or visual field loss
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WORK-UP
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Pupils | EOMs | Full eye exam with dilation | Cranial nerve testing | Visual field | OCT
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TREATMENT
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Ways to stop an active visual hallucination: · Go from a dark environment to a bright environment · Look directly at the hallucinations · Blink · Move eyes around · Talk to the hallucination · Walk directly toward the hallucination · Be around other people · Perform other tasks
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Treatments for Charles-Bonnet syndrome: Improve vision, decrease glare, and increase peripheral vision whether by spectacles, low vision devices, or surgery
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Antipsychotics such as olanzapine, fumarate, risperidone Cholinesterase inhibitor such as donepezil Anticonvulsants such as clonazepam | SSRIs and SNRIs have also shown some effectiveness
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Refer to neurologist and psychiatrist for further evaluation and treatment
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If the visual hallucinations do not bother the patient, treatment may not be necessary. Typically, once hallucinations start, they tend to last for about 18 months. Another study found that in about 75% of patients, the hallucinations lasted for 5 years or more. As time progresses, after the initial presentation of the hallucinations, the frequency of the hallucinations usually decrease
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FOLLOW-UP
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Once Charles-Bonnet syndrome is confirmed, repeat an eye examination to monitor ocular health
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ADDITIONAL LAB | TESTS
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MRI with and without contrast of the brain | Neurological evaluation | Psychiatric evaluation | Complete metabolic panel | CBC with differential
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ETIOLOGY
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Deafferentation theory: Small amounts of remaining stimulus from the retina or optic tract are enough to elicit a visual hallucination because the neurons are more sensitive
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Perceptual release theory: There is “unmasking” of other neuron activity, specifically in the visual association cortex which leads to a release of visual hallucinations. This causes images to be released from the subconscious to the conscious.
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Criteria for diagnosis of Charles-Bonnet Syndrome | · (1) No evidence of dementia · (2) No evidence of drug abuse · (3) No evidence of neurologic lesions or abnormalities · (4) No evidence of psychiatric disorders · (5) Presence of vision loss or visual field loss · (6) Realization that the visual hallucinations are not real · (7) Presence of complex visual hallucination within the past 4 weeks · (8) No other types of sensory hallucination such as auditory hallucinations · (9) Greater than 4 week interval between 2 visual hallucinations
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DIFFERENTIAL DX
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Schizophrenia, Multiple sclerosis, Parkinson’s disease, Lewy-body dementia, Recreational drug use, Stroke, Brain tumors
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NOTES
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Charles Bonnet syndrome has been shown to occur in 10-40% of patients with visual impairment
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Charles Bonnet syndrome typically occurs in patients with BCVA between 20/40 to 20/1600 in each eye, with an increase if BCVA is between 20/300 to 20/800 in each eye.
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Visual hallucinations are pleasant, not dangerous in nature, and they usually do not cause any anxiety or torment to the patient
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Visual hallucinations in Charles Bonnet patients are generally of a person or a face that is unfamiliar to the patient
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In 72% of cases the hallucinations in Charles Bonnet syndrome are in color. In fact, these colors are reported to be more vivid and bright than anything these patients have seen when they could see well.
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Hallucinations can occur 1-2 times a month or up to 30 times a month. The majority of hallucinations last anywhere from 1 minute to 60 minutes with the minority lasting for only a few seconds.
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Age related macular degeneration has been reported to be the most common ocular disease associated with Charles Bonnet syndrome.
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Visual hallucinations in some patients can be caused by stress, bright light, complete darkness, sensory deprivation, drowsiness, fatigue, embarrassment, solitude, increase in severity of visual impairment centrally and peripherally, and rate of vision loss (The faster or more sudden the vision loss, the more likely it will lead to hallucinations).
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