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Charles Bonnet Syndrome

What is Charles Bonnet Syndrome?
Charles Bonnet Syndrome (CBS) is a medical condition affecting some people with significant vision loss. Individuals with CBS see things that aren’t really there— colours, patterns, shapes, and even more complex scenes. There is low awareness and reporting of this elusive condition. Because hallucinations are most commonly associated with mental illness, experiencing symptoms of CBS may be confusing. However, CBS is not related to mental illness.

What Causes CBS?
Just as amputees can experience phantom limb sensations, people with CBS see things. The cause stems from the brain trying to ‘fill in the blanks’ for the lack of visual messages it would usually be receiving by releasing new patterns or stored images.

What are the symptoms?
People with CBS hallucinations are usually aware that what they are seeing is not real. The hallucinations are only visual, so people with CBS don’t hear, smell, or feel things that aren’t there. Visual hallucinations are often abstract in nature and may include colours, shapes, people, animals, cartoons, objects, and even more complex scenes. Images can appear at any time, lasting from a few seconds to several minutes.

Who is at risk?
One in five people that experience some form of vision loss and/or blindness may experience CBS, regardless of age. Loss of sight from macular degeneration, cataracts, glaucoma, or diabetic retinopathy can increase the risk of experiencing CBS. CBS can begin weeks or months after significant vision loss.

Can CBS be treated?
There is no known treatment of CBS. The most effective form of treatment can be peace of mind that the hallucinations are harmless and related only to vision loss.

Having a hallucination can be scary and confusing, especially when dealing with loss of sight.  Recognizing the cause of the problem and talking about it with family, friends, or a mental health counsellor can help reduce any stress. Doctors of optometry hope that bringing awareness to CBS will lead to better research, diagnosis and treatment.

Who is Charles Bonnet?
Charles Bonnet was a Swiss philosopher in the 1700s who documented the visual hallucinations experienced by his elderly grandfather, who also suffered from cataracts. The medical syndrome was coined almost 200 years later in the 1930s by Georges de Morsier, a French-Swiss neurologist.

If you are experiencing visual hallucinations as a result of vision loss, book an appointment today to speak with your local optometrist.

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