Charles Bonnet Syndrome

What is Charles Bonnet Syndrome?

Charles Bonnet Syndrome (CBS) is a common condition among people with serious vision loss characterized by temporary visual hallucinations.

Charles Bonnet Syndrome is not a mental illness, nor is it a symptom of dementia or any other disease. Rather, it is a condition specifically related to vision loss. While it is actually very common, awareness is limited, which can cause confusion and concern among those experiencing and diagnosing it.

While it is not yet known exactly why these hallucinations occur, researchers are beginning to believe they are related to an attempt by the brain to fill in information that would normally be obtained from the eyes.


CBS hallucinations tend to begin in the months immediately following a loss of sight. Hallucinations can be very distressing, but aren’t usually permanent. Symptoms generally decrease in frequency after about a year to 18 months, although some people may have the condition for five years or more.

Images can appear at any time and can last from just a few seconds to several minutes.

People with CBS hallucinations are usually aware that what they’re seeing is not real. CBS hallucinations only affect sight, which means that people with CBS don't hear, smell or feel things that aren't there.

These visual hallucinations can take many forms, ranging from simple shapes and lines to detailed images of people and landscapes. They may seem “real” (like seeing cows in a field when the field is actually empty) or “surreal” (like seeing dragons). Most frequently, people will see patterns or simple shapes, however there are many accounts of more complex hallucinations, including:

  • Little men holding umbrellas at the end of the bed
  • Women in red dresses sweeping the floor
  • Cloakroom tickets lining the walls and ceiling
  • Soldiers marching down the street

It’s clear that CBS affects every person differently, so it’s important to choose a coping strategy that works for each unique case.

Am I at risk?

You may be at risk for Charles Bonnet Syndrome if you have lost some of your vision to conditions like:

  • macular degeneration
  • glaucoma
  • diabetic retinopathy

If this describes you, it’s a great first step that you are armed with the information that CBS exists, and that you are not alone. If you believe you have started to hallucinate (seeing things that you know aren’t really there), talk to your doctor about CBS.

A recent CNIB study showed that about one in five new CNIB clients had experienced some form of hallucination associated with vision loss.

Diagnosing CBS

Although Charles Bonnet Syndrome occurs relatively frequently in people who have lost vision, few people (including the medical community) have actually heard of it. There is also some reluctance among people experiencing hallucinations to discuss it, as they fear they’re experiencing mental health issues. By talking about it, you can help open the dialogue between patients and doctors.

There isn’t one simple test your doctor can do to determine your diagnosis. Likely, they will try to rule out other conditions that could be causing visual hallucinations, in the absence of which they may diagnose Charles Bonnet Syndrome. There are, however, other conditions that affect the brain that may cause hallucinations. It is important for your doctor to rule these out before confirming a diagnosis of Charles Bonnet Syndrome.

Coping Strategies

There is no cure for CBS, but there are coping strategies that can make it easier to live with.

  • Shifting your eyes left to right every second for up to half a minute, without moving your head, may help diminish hallucinations. 
  • Many people experience hallucinations when they are sitting quietly. Try putting the TV or radio on, or moving locations.
  • Try adjusting your lighting. If you are experiencing a hallucination in dim light, turn on a bright light. If you are in a bright space, shut the curtains or dim the lights.
  • Consider telling family and friends about what you see or discuss it with other people who are experiencing CBS.

Our research

There are very few studies on the prevalence of CBS, so CNIB set out to get some answers for people like Doris. Through our research, we asked all new CNIB clients undergoing low vision assessment over a four month period if they had experienced hallucinations.

We had more than 2,500 respondents, and 18.8% said they’d experienced hallucinations.

We then explored the experiences of those living with visual hallucinations in greater depth, speaking to 35 clients about the nature of their hallucinations and their thoughts and feelings about them. Here is what we found:

  • The most common hallucinations were of people, animals, and shapes or patterns.
  • Most people saw hallucinations almost every day
  • Most people saw hallucinations for just a few seconds or minutes at a time
  • About a third of people found they could get rid of their hallucinations temporarily by blinking or moving their head
  • About half of participants saw their hallucinations mostly at night, in darkness, or falling asleep
  • About a third of participants did not notice any pattern to their hallucinations
  • Two-thirds of participants did not find their hallucinations to be troublesome

Our hope is that this research will increase the awareness and understanding of people’s experiences living with visual hallucinations, and enable professionals to better meet the needs of those with Charles Bonnet Syndrome.