Charles Bonnet Syndrome and Macular Degeneration

Scheie Eye Institute, University of Pennsylvania
A person with macular degeneration seeing a hallucination of an elephant due to Charles Bonnet Syndrome
Learn about Charles Bonnet syndrome, which can cause visual hallucinations in people living with macular degeneration, glaucoma, or cataracts.

One sensitive issue often confronting people with advanced macular degeneration, glaucoma, or cataracts is visual hallucinations, called Charles Bonnet syndrome. Charles Bonnet was a Swiss philosopher in the 18th century who realized that his grandfather’s visual hallucinations were due to eye disease rather than mental illness.

The brain essentially creates these hallucinations because the normal amount of visual information coming from the eyes is reduced. The images can be complex and can include detailed patterns or fully formed images such as animals, artwork, faces, or scenery, and can last anywhere from seconds to hours. People are reluctant to mention the hallucinations because they think it suggests mental infirmity or that they are “going mad.” Rather, it is actually just a common consequence of impaired vision.

People with Charles Bonnet syndrome realize that the images they see are not real. In contrast, people with psychiatric illness may experience delusions in which they believe the hallucinations they see are real. These delusions may be associated with hearing voices as well.

Video: Charles Bonnet Syndrome

Charles Bonnet Syndrome can be compared to phantom limb syndrome. This is a condition in which amputees still “feel” an amputated limb, because the cells in the brain responsible for sensing that limb continue to fire signals despite the absence of the limb. Similarly, in Charles Bonnet syndrome, the part of the brain responsible for vision substitutes illusions when it lacks input from the macula.


This content was first posted on: October 30, 2016

The information provided here is a public service of the BrightFocus Foundation and should not in any way substitute for personalized advice of a qualified healthcare professional; it is not intended to constitute medical advice. Please consult your physician for personalized medical advice. BrightFocus Foundation does not endorse any medical product, therapy, or resources mentioned or listed in this article. All medications and supplements should only be taken under medical supervision. Also, although we make every effort to keep the medical information on our website updated, we cannot guarantee that the posted information reflects the most up-to-date research.

These articles do not imply an endorsement of BrightFocus by the author or their institution, nor do they imply an endorsement of the institution or author by BrightFocus.

Some of the content may be adapted from other sources, which will be clearly identified within the article.

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