What is Charles Bonnet Syndrome?
Reviewed by: HU Medical Review Board | December 2018 | Last updated: March 2020
There are a variety of complications of macular degeneration, and some may not initially seem related to the conditions. Charles Bonnet Syndrome (CBS) is one such complication.
CBS is a rare condition that causes visual hallucinations in an individual, but the hallucinations are not caused by a mental illness.1 Most people with CBS do have a visual impairment, such as decreased visual acuity or constricted field of vision.
The hallucinations can be simple shapes, patterns, or may be complex images of people or animals.2 They can last seconds to hours, and can recur, sometimes for years.
What causes visual hallucinations?
The actual cause of these hallucinations is not entirely known, but it’s thought to stem from the idea that vision loss causes the interruption of visual-sensory nerve cells, which then causes disinhibition and spontaneous firing of visual-cortical regions in the brain.1 In a sense, the brain continues to interpret images, even though no images are actually being sent to the brain. Functional MRI studies in individuals with CBS have found a relationship between visual hallucinations and spontaneous activity of the ventral, or frontal, occipital lobe.1
Diagnosing Charles Bonnet Syndrome
There aren’t precise statistics on CBS, mainly because it can be hard to accurately diagnose, especially among older adults. It may also be underreported because individuals with CBS know their hallucinations are not real and may fear being stigmatized, misunderstood, or misdiagnosed.2 For health care providers meeting with a patient reporting visual hallucinations, it’s important to get a complete picture of what’s going on, as well as a health history that includes questions about visual disorders, in order to accurately assess and diagnose for CBS.
Symptoms of CBS
The hallucinations in CBS can vary. They can be shapes, flashes of light, or patterns; they can also be people, animals, or even whole scenes. No other sense is involved in the hallucination, and there is no underlying psychiatric disorder or dementia.2 The hallucinations often occur in the morning, when the person wakes up, and there’s usually a pattern or routine to the hallucinations. They often occur when the eyes are open and will disappear once the eyes are closed.1 There is no relationship between the complexity or detail of the hallucinations and the severity of visual loss.2
Treatment can vary among individuals with CBS, since there is no one treatment that works for everyone. Treatment options can include2:
- Low vision aids to help maximize the vision you do still have
- Reassurance about the nature and origin of the hallucinations
- Antipsychotic and neuromodulating medications like carbamazepine (Tegretol), clonazepam (Klonopin), quetiapine (Seroquel), or olanzapine (Zyprexa). These medications do not suggest that you are being treated for a psychiatric condition, rather they are designed to modulate brain activity and may be helpful for CBS
- Minimizing any known triggers to keep CBS aggravation to a minimum. Triggers can include stress, sensory deprivation, anxiety, social isolation
- Programmed blinking/intermittent opening and closing of the eyes3
- Regular, consistent checkups with the eye doctor to monitor AMD and any other symptoms or complications like CBS
What can you do?
With a chronic condition like macular degeneration, complications can arise that don’t immediately seem related to the condition but are actually related to it. It’s important to note anything out of the ordinary and talk to your doctor about it; even if it turns out to be nothing, it’s better than ignoring it or not mentioning something that might end up getting worse as time goes on rather than being treated early. There are treatments that might help CBS, so tell your eye doctor about any visual hallucinations you might have had or are having. Your treatment team can help you through this.