Charles Bonnet Syndrome


Charles Bonnet (1720-1793) was a Swiss naturalist and philosopher. He was the first scientist to describe, in 1760, the visual hallucinations experienced by his grandfather who was vision impaired.

Charles Bonnet syndrome

Charles Bonnet syndrome causes a person whose vision has started to deteriorate to see things that aren’t real (hallucinations).

The hallucinations may be simple patterns or detailed images of events, people, or places. They are only visual and do not involve hearing things or any other sensations. It is important to be aware that hallucinations associated with Charles Bonnet syndrome are caused by failing eyesight. They’re not caused by a mental health problem or dementia. While in some instances the visions are vivid most people with Charles Bonnet syndrome are usually aware that they’re not real.

Please contact your GP if you’re experiencing hallucinations so that they can investigate the cause.

2 Main Types of Hallucination

There are 2 main types of hallucination that people with Charles Bonnet syndrome tend to experience. They may see:

  • Simple repeated patterns
  • Complex images of people, objects or even landscapes
  • Simple repeated patterns can take the form of grids, shapes or lines, which can appear in bright or vivid colours. The patterns may be across or cover everything the person sees.
  • More complex hallucinations can involve people, places, animals and insects.
  • Most people don’t see hallucinations of people they know or past events they have experienced.
  • The hallucinations aren’t usually unpleasant or threatening but may be slightly frightening when first experienced.
  • They can sometimes occur out of the blue and can last for a few minutes or several hours.
  • They may be moving or static.

Who is affected?

Charles Bonnet syndrome affects people who have lost most or all of their eyesight.

It’s more likely to occur if vision loss affects both eyes.

According to studies, up to half of all people with Macular Degeneration, a gradual loss of central vision, may experience Charles Bonnet hallucinations at some time.

People of any age can be affected by Charles Bonnet hallucinations, but they tend to occur later in life after a person starts to lose their sight.

The hallucinations often begin when a person’s sight suddenly deteriorates.

The main cause of Charles Bonnet syndrome is thought to be vision loss and how the brain reacts to it. It’s not clear how loss of vision leads to hallucinations, but research is beginning to help us better understand the relationship between the eyes and the brain. When a person starts to lose their sight, their brain doesn’t receive as much information as it used to. It’s thought the brain sometimes responds by filling in the gaps with fantasy patterns or images that it’s stored. These stored images are experienced as hallucinations.

Worried mature man touching his head

What effect can hallucinations have?

Visual hallucinations are a normal response the brain has to the loss of vision.

But as Charles Bonnet syndrome isn’t widely known, many people worry about what it means and fear they may be developing a serious mental health problem or dementia. People who experience these hallucinations often keep the information to themselves, afraid that people will not understand or assume that they have a mental illness or have dementia.

It can also cause practical problems. People who see complex hallucinations may find it difficult to get around. Streets and rooms may be distorted, and brickwork or fencing may appear directly in front of you, making it difficult to judge exactly where you are and whether you can walk straight ahead. Some people can overcome this problem by having good knowledge of their surroundings.

Complex hallucinations can be unsettling. Although the visions may not be frightening, it can be disturbing to suddenly see strangers in your home or garden.

The hallucinations often improve over time, with episodes becoming shorter and less frequent.

Recent evidence suggests most people will still have occasional hallucinations 5 years or more after they first started.

If the hallucinations do stop entirely, there’s always a chance they’ll reappear after a further decline in vision.

Treating Charles Bonnet syndrome

There’s currently no cure for Charles Bonnet syndrome.

Simply understanding that the hallucinations are a normal consequence of vision loss, rather than a mental health problem, can be very reassuring and help the person cope better. No specific medication has been shown to stop hallucinations caused by Charles Bonnet syndrome.

Self-help measures

There are some things you could try yourself to help relieve your hallucinations when you experience them.

For example, when a hallucination starts, you could:

  • change the lighting conditions to see if it disappears – if you’re in a dimly lit area, switch on more lights or move to somewhere that’s brighter; if you’re in a brightly lit area, make it dimmer
  • move your eyes from left to right – do this once every second 15 times without moving your head, then pause for a few seconds and repeat; it’s worth trying this up to 4 or 5 times
  • stare at the image and blink rapidly or reach out to touch the vision – try this for a few seconds
  • move around or perform a task – for example, get up to make a cup of tea
  • make sure you’re well rested and are getting enough sleep at night – the hallucinations may be worse when you’re tired or stressed

Help and support

If you have Charles Bonnet syndrome, talking about your hallucinations and how they make you feel may help you to cope better. You could try talking to your family, friends, GP, Optometrist or Ophthalmologist.

NCBI’s Community Resource Workers (CRW) are also available to listen to your experiences and will assist you develop strategies to help deal with the hallucinations. For more information on how to access your local CRW please call our InfoLine on 1800 911 250 or online

There aren’t any specific support groups and forums for people affected by Charles Bonnet syndrome but we in NCBI offer support in many ways including, if appropriate and with consent, putting you in touch with individuals dealing with Charles Bonnet syndrome.

Further contacts

Esme’s Umbrella, an awareness campaign for Charles Bonnet syndrome, has a website with links to information and helpful resources for both those affected by it and for healthcare professionals. The website can be found here: