What Is Charles Bonnet Syndrome?

Charles Bonnet syndrome (CBS) is a condition that can affect you if you have lost some of your sight. It can cause you to see things that are not there (hallucinations). These can be scary and upsetting, especially if you do not know why they are happening. You may wonder if your mind is unwell and be afraid to tell anyone.^1-5

Fortunately, you can rest assured that hallucinations that happen with CBS are harmless. Your brain is just reacting to your sight loss.^1-4

Who gets Charles Bonnet syndrome?

Anyone with sight loss can get CBS. But most people who get it are between 70 and 85 years old. It is hard to say how common it is because many people do not report their hallucinations. They fear they are mentally ill. But those who have CBS do not have psychosis, dementia, or any other cause of hallucinations besides vision loss.^1,3-5

As many as 2 out of 3 people do not know about CBS. And nearly half of family doctors are unaware of it.^1,3-5

Some sources report that as many as 1 in 3 people with vision loss get CBS. But others suggest as few as 1 in 173. Most studies agree that your chances of having CBS increase as your vision decreases.^1,3-5

What vision loss conditions are linked to CBS?

CBS happens when sight loss interferes with the messaging pathway between your eyes and brain. This pathway includes 3 key structures:^1,2,4-6

• The light-sensitive tissue at the back of your eye (retina)
• The nerve that carries sight messages to the brain (optic nerve)
• The back part of the brain that interprets sight messages from the optic nerve (occipital lobe)

Vision loss conditions related to CBS include:^1-5

• Macular degeneration
• Glaucoma
• Diabetic retinopathy
• Retinitis pigmentosa
• Optic neuritis
• Cataracts

Why am I seeing things that are not there?

Researchers do not know the exact cause of CBS. But they have suggested a few possible reasons it happens.^1-6

First, with regular vision, your optic nerve continually sends your brain picture information. These images stimulate your brain’s vision center. When your eye nerve sends fewer picture messages, the brain misses the constant input. So, it makes up images for you to see.^1-6

Also, researchers have studied brain images of people not using their eyes. The brain’s sight area was still active. This may mean that the brain contains unreal images that it usually does not process. But when real images are few, the brain releases the unreal ones.^2,3,5,6

Finally, there is the phantom image theory. When some people lose an arm or leg, their brain still sends pain messages about the limb. In CBS, the brain may send phantom sight messages even when the eye cannot see.^3-6

What are the visual symptoms of CBS?

You may experience a variety of hallucinations, depending on what part of your brain sends them. You will usually know they are not real. You may see images that are:^1-3,5-7

• Simple, such as patterns, lines, or shapes
• Complicated, like faces, people, animals, buildings, or scenes
• Imaginary or realistic
• Colorful or black-and-white
• Moving or still
• Pleasant or unpleasant
• Brief or long-lasting

The images may bother you at first, but you may get used to them over time. Six in 10 people pay little attention to them. Seven in 10 even find them nice to look at. But up to 1 in 3 people describe them as scary, troublesome, and disruptive.^2-5

How will my doctor know if I have CBS?

Your doctor will ask you questions about your health history. Then, they can do tests to rule out causes other than CBS. These tests may include:^2,3

• Brain imaging procedures
• An EEG, which looks at brain waves
• Lab work
• Genetic testing

Your doctor also may ask you about any drugs you are taking. There are some prescription as well as recreational drugs that can cause hallucinations.^2,3

What are the treatments for CBS?

There is no known cure for CBS. However, certain actions may lessen its effects. You can try:^1-5

• Blinking, looking away from the image, and closing your eyes
• Using brighter lighting to stimulate the brain and curb its tendency to create unreal pictures
• Getting together with family, friends, or a support group to stimulate your brain
• Managing the stress of dealing with CBS with relaxation, breathing, meditation, yoga, physical exercise, or talk therapy

If you remain worried or upset by the visions, speak to your doctor. They may prescribe drugs that treat anxiety or depression. Such drugs may help you manage your troubling feelings.^1-5

The images you see may decrease with time, or they may last for months or years. If your vision loss condition is treatable, treating it may end the hallucinations.^2,3,5,6

What is the takeaway?

Above all, remember that having CBS is not a sign of mental illness. Instead, CBS causes people with low vision to see things that are not there. If you see hallucinations, speak to your doctor or an eye specialist about CBS. They can rule out other causes and help you manage the condition.^1-6