What Is Charles Bonnet Syndrome?

Charles Bonnet Syndrome (CBS) is a condition that some people get when they lose some or all their vision. It causes them to have visual hallucinations (seeing things that aren't really there).

What Causes Charles Bonnet Syndrome?

With healthy vision, light enters the eye and is received by the retina (the light-sensitive tissue in the back of the eye). The retina converts these light rays into visual messages, which are sent to the brain, so we can see.

When people lose vision from diseases like age-related macular degeneration, glaucoma, or diabetic retinopathy, their visual system doesn't process new images. Without visual data coming in through the eyes, the brain fills the void and makes up images or recalls stored images for you to see. This is what causes the visual hallucinations of CBS.

What Are Symptoms of Charles Bonnet Syndrome?

The main symptom of CBS is having visual hallucinations. Most people have them when they wake up. What people see varies, but can include:

• repeating patterns of lines, dots, or other geometric shapes
• landscapes, such as mountains or waterfalls
• people, animals, or insects
• people dressed in costume from an earlier time
• imaginary creatures, like dragons

The hallucinations may move or remain still, and they can appear in black and white or color. The length of the hallucinations can last seconds, minutes, or hours.

How Is Charles Bonnet Syndrome Diagnosed?

There is no special test to find out if you have CBS. Your doctor will want to talk to you about your medical history. They will try to rule out other sources of visual hallucinations, including:

• mental health problems, like schizophrenia
• other neurological (brain) conditions, like dementia or Parkinson's
• whether you take certain medications

If you have vision loss and visual hallucinations without these other conditions, you likely have CBS.