Charles Bonnet Syndrome – Fast Facts

9/2/14

“The theater of the mind could be generated by the machinery of the brain.”

What is Charles Bonnet Syndrome (CBS)?

1. It was discovered in 1790 by Charles Bonnet.
2. 10-40% of low vision individuals experience hallucinations.
3. Only 1% of them acknowledge it!
4. Images usually appear suddenly and stop as suddenly. They don’t fade in and out.
5. Most of the time, the images are not people or things familiar to you.
6. They may be startling, but they are not frightening or sinister.
7. It is like watching a movie as the images don’t interact with you, unlike psychological images that interact with you and you with them.
8. CBS usually stops within 12-18 months.

Why does it happen?

1. Vision takes place in the brain.
2. Different parts of the visual brain are triggered by different information. Faces fire up one part of the brain; buildings another and the scientists can see what activity is happening where.
3. As you lose vision and the visual parts of the brain are not getting any input, they become hyperactive and excitable. This causes them to start to “fire” spontaneously.
4. Example – If you damage (or lose vision) in a particular area, such as the one for faces, you lose the ability to recognize faces.  That will create abnormal activity in that area and you will hallucinate faces (*see more detailed explanation below).

What Can You Do?

1. There is no cure or truly effective treatment.
2. Acknowledge that you are having the visions and talk about them.
3. Look on them as an experience rather than a problem. It’s fascinating how the brain works, isn’t it?
4. Having a good sense of humor can help in adjusting well to CBS.
5. Sometimes, eye exercises — such as looking from left to right without moving one’s head for 15 to 30 seconds — can help stop a hallucination.
6. Increased room lighting can sometimes prevent an episode of CBS visions if they commonly take place in low light. Changing the lighting in the middle of an episode may stop them.
7. Stress and fatigue could be contributing factors, so try to get enough rest and reduce stress.
8. Identify and engage in activities you enjoy; keep up your social life. Reduced social isolation, boredom, lack of stimulation, and low activity seem to increase CBS.

For more information on Charles Bonnet Syndrome, please go to the Macular Degeneration Partnership website.

*Testing for functional brain imagery as individuals hallucinate can find different parts of the brain are activated.

Your brain has a particular area or lobe where vision is interpreted. The light energy that bounces off objects enters the eye and is converted to chemical energy by the retinal cells. That energy is sent through the optic nerve where processing of the vision starts to occur. When it reaches the visual cortex, it is sent to very specific areas of the brain and specific areas of the brain see specific things.

The fusiform gyrus processes faces, but different areas process the parts of faces. While damage in the fusiform gyrus causes you to lose the ability to recognize faces, abnormal activity in that area will  cause you to hallucinate faces. An area in the anterior part of this gyrus is where teeth and eyes are recognized. There are other areas that specifically sees cartoons and another part for buildings and landscapes.

Judith Delgado
Executive Director
Macular Degeneration Partnership
A Program of Discovery Eye Foundation