Charles Bonnet syndrome
Charles Bonnet syndrome is a condition that causes visual hallucinations in people with sight loss and of a sound mind. It's more common in older people, who are more likely to have eye conditions such as macular degeneration, cataracts, and glaucoma, which can lead to visual impairment.
It can be very unsettling to start seeing things that aren't real, and you might worry this is a sign of mental illness or dementia. It's important to see your GP if you start to experience hallucinations. They'll discuss your symptoms and help you get a diagnosis.
Many people aren't aware that visual hallucinations can be a normal response of the brain to sight loss. It's thought the brain tries to compensate for the loss of information from the eye by creating these images.
The hallucinations tend to improve with time, though they can still happen occasionally up to five years after they first begin (Source: NHS). There are tips you can use to stop hallucinations or make it easier to cope with them. Speaking to others with the condition is also a great source of support and reassurance.
Charles Bonnet syndrome treatment
There is currently no medical cure for Charles Bonnet syndrome, but the condition tends to improve in time, with hallucinations becoming shorter and less frequent.
It can be helpful for people who experience Charles Bonnet syndrome to understand more about the condition. The hallucinations are a reaction of the brain to sight loss, rather than a mental health problem or other illness.
The vivid nature of the images people see with Charles Bonnet syndrome can make them quite disruptive to daily living. While there is no set medical treatment yet, talking about your hallucinations with others can be reassuring and reduce feelings of isolation. People with Charles Bonnet syndrome say that making changes to their environment can also help reduce hallucinations. For practical tips on how to try to stop hallucinations or make them easier to live with, learn more about living with Charles Bonnet syndrome.
Rarely, people experiencing distressing hallucinations may be prescribed medicines normally used to treat other conditions such as anxiety or Parkinson's disease. These help some people, but specialists only prescribe them in certain circumstances as they have side effects.
Symptoms of Charles Bonnet syndrome
Charles Bonnet syndrome causes you to see things that aren't there, known as visual hallucinations. These aren't accompanied by other sensations such as hearing noises or smelling or feeling things that aren't real. Unlike delusions, people having these hallucinations are aware they're not real.
The images you see can appear in black and white or colour, can be moving or still, and last for minutes or hours at a time.
Charles Bonnet hallucinations are associated with significant sight loss and often begin after a sudden or significant loss of vision. The frequency and length of hallucinations usually subside with time but can still happen up to five years after they start.
What causes Charles Bonnet syndrome?
Charles Bonnet syndrome happens in people with significant sight loss and is more likely if your vision in both eyes is affected.
It's a normal response of the brain to being deprived of the visual information it's used to receiving from the eyes. It's thought that the areas of the brain responsible for processing images try to 'fill the gap' left by the lack of visual stimulus. This creates the images you experience as hallucinations.
Charles Bonnet syndrome risk factors
Charles Bonnet syndrome is associated with low vision. Some common risk factors make this more likely:
- Charles Bonnet syndrome is more likely among older people who are more likely to be living with a range of eye conditions.
- Eye conditions that lead to low vision including age-related macular degeneration, cataracts, glaucoma, and diabetic retinopathy.
How is Charles Bonnet syndrome diagnosed?
A healthcare professional usually diagnoses Charles Bonnet syndrome after taking a complete medical history. If you start experiencing hallucinations, speak to your GP or ophthalmologist.
To make a diagnosis, a doctor will:
- Ask about your medical history, including any eye conditions.
- Ask about your symptoms, including details of your hallucinations.
- Sometimes do tests such as neurological and memory tests to rule out other possible conditions that can cause hallucinations.
When to get medical advice
If you experience hallucinations, see your GP as soon as possible. If you have an eye disease or condition that has led to visual loss, you may have Charles Bonnet syndrome. Your doctor will discuss your symptoms and want to rule out any other conditions.
If you have an ophthalmologist, you can ask them about your symptoms as well.
Living with Charles Bonnet syndrome
It can be very strange to see vivid images, scenes, or even people as part of your surroundings, which aren't real. It often gets easier with time, but at first, these hallucinations can be not just surprising but alarming.
Talking to other people having similar experiences can be very reassuring. They know what you're going through and often have practical ideas and tips you might not have tried.
Frequently asked questions
Medically reviewed by: The Royal College of Ophthalmologists on 18/10/2022
Edited by: Nick Astbury FRCS FRCOphth FRCP
Clinical Associate Professor
The Royal College of Ophthalmologists champions excellence in the practice of ophthalmology and is the only professional membership body for medically qualified ophthalmologists. The RCOphth is unable to offer direct advice to patients. If you’re concerned about the health of your eyes, you should seek medical advice from your GP, optometrist or ophthalmologist.