Charles Bonnet Syndrome: Causes, Symptoms, Diagnosis, Treatment, and Prevention
The Charles Bonnet syndrome (CBS) causes visual hallucinations in people who are visually impaired or have low vision. A person with CBS is aware that the hallucinations are not real and does not suffer any other cognitive difficulties. The hallucinations can be simple, like shapes or patterns, or complex, like animals or people.
Causes of Charles Bonnet Syndrome
Despite not knowing the exact cause of CBS, it appears to be related to the brain's response to vision loss. The brain may try to fill in the gaps in visual information by creating images from memories or imagination when the eyes cannot send enough visual information to the brain. When you close your eyes or in the dark, you may see shapes or patterns.
People with low vision or vision loss can develop CBS, but the condition is more prevalent in older adults and people with conditions affecting the retina, such as age-related macular degeneration, diabetic retinopathy, glaucoma, or cataracts. A stroke, eye surgery, or eye removal can also cause CBS.
Symptoms of Charles Bonnet Syndrome
The main symptom of CBS is seeing visual hallucinations that are not caused by any external stimulus. The hallucinations can vary in:
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Duration: They can last from a few seconds to several hours or days.
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Frequency: They can occur once or several times a day, or less often.
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Intensity: They can be clear or blurry, colorful or black and white, realistic or distorted.
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Content: They can be simple, such as lines or dots, or complex, such as faces or landscapes.
Hallucinations can appear anywhere in the visual field, move or remain static. They may overlap with the real environment or replace it entirely. They can be pleasant or unpleasant, but rarely cause fear or distress.
Some people with CBS may also experience other visual phenomena, such as flashes of light, distortions, or illusions.
Diagnosis of Charles Bonnet Syndrome
There is no specific test for CBS, but the diagnosis is based on the following criteria:
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The person has low vision or vision loss.
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The person sees visual hallucinations that are not caused by any external stimulus.
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The person is aware that the hallucinations are not real and does not have any other cognitive problems.
The diagnosis of CBS can be challenging, as many people with CBS may not report their hallucinations for fear of being labeled as mentally ill or losing their independence. The health care provider must ensure that people with low vision or vision loss are informed about visual hallucinations and reassure them that CBS is a benign and common condition.
The person may undergo a physical examination, blood tests, and imaging tests, such as an MRI or CT scan, in order to rule out other possible causes of visual hallucinations.
Treatment of Charles Bonnet Syndrome
There is no specific treatment for CBS, but the following strategies may help reduce the frequency or severity of the hallucinations:
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Improving the vision: Using glasses, magnifiers, or other aids may help enhance the visual input and reduce the brain's need to create images.
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Stimulating the vision: Engaging in activities that involve visual attention, such as reading, watching TV, or playing games, may help distract the brain from producing hallucinations.
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Confronting the hallucinations: Acknowledging, talking to, or staring at the hallucinations may help make them disappear or change.
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Changing the environment: Altering the lighting, moving the eyes, or changing the position may help modify or stop the hallucinations.
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Seeking support: Joining a support group, talking to a counselor, or sharing the experience with family and friends may help cope with the emotional impact of the hallucinations.
Anticonvulsants, antidepressants, or antipsychotics may be prescribed to treat CBS in some cases. It is important to use them with caution and under medical supervision because they have limited evidence of effectiveness and may have side effects.
Prevention of Charles Bonnet Syndrome
There is no known way to prevent CBS, but maintaining good eye health and regular eye check-ups may help prevent or delay vision loss and reduce the risk of developing CBS. Some lifestyle factors that may help protect the eyes include:
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Eating a balanced diet rich in antioxidants, vitamins, and minerals.
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Quitting smoking and limiting alcohol intake.
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Wearing sunglasses and hats to protect the eyes from UV rays.
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Avoiding eye injuries and infections by wearing protective eyewear and practicing good hygiene.
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Managing chronic conditions that may affect the eyes, such as diabetes, high blood pressure, or high cholesterol.
Outlook for Charles Bonnet Syndrome
The condition is not life-threatening or progressive, and doesn't affect a person's intelligence or mental health. However, it can affect a person's quality of life and well-being, especially if the hallucinations are frequent, persistent, or distressing.
Most people with CBS experience hallucinations that decrease or disappear over time, as the brain adjusts to the loss of vision or as the vision stabilizes. This may take months or years, depending on the underlying cause of the vision loss.
For some people with CBS, the hallucinations may persist or recur, but they may learn to live with them and cope with them effectively.
