Charles Bonnet Syndrome, Hallucinations & Macular Degeneration

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.

View a transcript of the video.