Eyes Charles Bonnet Syndrome

Overview

Charles Bonnet Syndrome (say: sharl boh-NAY) is a condition where a person with poor or failing eyesight sees things that are not really there. These are called visual hallucinations. They can be simple, like patterns, shapes or bright colours, or detailed, like faces, animals, people or whole scenes. The important thing to know is that the person usually knows these images are not real. Charles Bonnet Syndrome is not a mental illness and it is not a sign of dementia. It happens because the brain is not getting enough pictures from the eyes, so it starts to fill in the gaps on its own.

It seems to be quite common among people who have lost a lot of their sight, though no one knows the exact numbers. Studies suggest that between 1 in 10 and 1 in 5 people with significant sight loss may have it at some point. Because many people keep it to themselves, it is likely under-reported.

It mostly affects older adults who have lost sight later in life, for example from age-related macular degeneration, glaucoma or diabetic eye disease. It can happen at any age, including in children with poor vision, but that is much less common. It can affect anyone who has lost a lot of vision, whatever the cause.

Symptoms

Common symptoms

• Seeing patterns, grids, lines, dots, blobs or bright colours
• Seeing detailed images such as faces, people, animals, buildings, trees or whole scenes
• Images that appear suddenly and may move, shrink, grow or change shape
• Images that only you can see, and that disappear when you look directly at them or blink
• Images that are silent — no sound, smell or touch comes with them
• Episodes lasting from a few seconds to several hours
• Hallucinations that are more likely in dim light, when tired, or when sitting quietly with little to do
• Knowing, at least most of the time, that what you are seeing is not real

Symptoms in children

• Children may describe seeing pictures, animals or people that others cannot see
• They may seem frightened or upset by what they see, especially if they do not understand it
• They may not realise that other people do not see the same things
• A child with poor vision who starts describing unusual sights should be checked by an eye doctor

Symptoms in older adults

• Hallucinations often start after a further drop in eyesight, such as after cataract surgery or a change in vision
• People may worry they are developing dementia or 'going mad', which adds to the distress
• Some people become anxious, avoid going out, or stop telling family and carers what they see
• Being startled by an image can raise the risk of a fall
• Poor lighting at home and being alone for long periods can make episodes more frequent

Causes

Main causes

• Any condition that causes serious sight loss. The most common are age-related macular degeneration, glaucoma, diabetic eye disease and cataracts.
• When the eyes send fewer pictures to the brain, the visual parts of the brain try to fill in the missing information. These 'fill-in' pictures are the hallucinations.
• Sight loss from other causes, such as injury to the eye, eye surgery, or conditions present from birth, can also trigger it.

Risk factors

• Having a lot of sight loss, especially in both eyes
• Being older, though this is because sight loss is more common with age
• Being in low light or in a quiet, unstimulating place for long periods
• Feeling tired, stressed or unwell
• Being socially isolated or spending a lot of time alone
• Living with hearing loss as well as sight loss

When to see a doctor

See a doctor urgently if:

• If you suddenly lose vision, or notice new flashing lights, a shower of floaters or a dark curtain across your sight
• If hallucinations come with confusion, fever, drowsiness or a change in how alert you are
• If you have new visual symptoms along with weakness, numbness, speech trouble or a severe headache
• If the images are so frightening that you feel unsafe or unable to cope

Book a routine appointment if:

• If you start seeing things that are not there — even if they do not bother you — so your doctor can check your eyes and rule out other causes
• If episodes are becoming more frequent, longer or more upsetting
• If you are avoiding going out, feeling low, or not sleeping because of what you see
• If you are caring for someone who describes seeing things, help them book an appointment and go with them

Diagnosis

There is no single test. Your doctor or eye specialist will make the diagnosis by listening carefully to what you see, when it happens, and how you feel about it. They will check your eyesight and eye health, review your medicines and general health, and rule out other causes of visual hallucinations such as infections, migraine, some neurological conditions, or medication side effects. Because people often hide the symptoms, doctors may ask about them directly when someone has poor vision.

Tests that may be done

• A full eye examination, including a check of how well you see and an examination of the back of the eye
• Questions about what you see, when it happens, and whether you know it is not real
• A review of your medicines and any recent changes to them
• Blood tests to check for other conditions if needed
• A memory and thinking check if there is any concern about confusion
• A brain scan in some cases, if the doctor wants to rule out other causes
• A hearing check, since hearing loss can go along with sight loss

What to expect at your appointment

You may be asked to describe or even draw what you see. Keeping a short diary before your appointment — noting what you saw, the time of day, the lighting and how you felt — can really help. Most people do not need lots of tests, and many are reassured once the diagnosis is explained. You should feel free to ask questions and to say if the images upset you.

Treatment

There is no cure for Charles Bonnet Syndrome, but the most powerful treatment is understanding it. Once people know the images are caused by sight loss and are not a sign of madness or dementia, many feel much calmer and the episodes often become less troubling. Many people find the hallucinations become less frequent over months or years, though for some they continue. Treatment focuses on improving your vision where possible, making episodes easier to manage, and supporting your wellbeing.

Self-care at home

• Turn on a light or change the lighting when an image appears
• Blink hard several times, look away, or move your eyes from side to side or up and down
• Stand up, walk around or change what you are doing
• Look directly at the image — it often fades when you do
• Keep a diary of when episodes happen so you can spot your triggers
• Have a plan ready, so that if an image appears you know what to do and feel more in control
• Keep your glasses or low-vision aids up to date and use them as advised
• Try to stay socially connected and keep your mind busy with audio books, radio, music or hobbies

Medical treatments

The first step is usually to treat any underlying eye condition and to make sure your glasses or low-vision aids are as helpful as possible. Talking therapies such as cognitive behavioural therapy can help you cope with distressing images and reduce anxiety. If hallucinations are severe, very distressing, or do not settle, a specialist may consider medication in some cases — always discussed carefully with you and your eye or mental health team. Your doctor will explain the options and the balance of benefits and risks.

When is surgery considered?

Surgery is not a treatment for Charles Bonnet Syndrome itself. However, some people develop it after eye surgery, such as cataract surgery, or when their vision changes. If you have an eye condition that can be treated with surgery, your eye specialist will discuss whether it might help your overall sight.

Living with this condition

Many people find that the images fade into the background once they understand them. Simple habits make a big difference: good lighting at home, keeping busy with things you enjoy, and having a plan for when an image appears. Telling family, friends or carers what you see can take away a lot of the worry, and it helps them support you instead of being puzzled or alarmed.

Lifestyle tips

• Keep rooms well lit, especially in the evening and on dull days
• Reduce glare and use lamps where you read, eat or sit
• Keep to a regular sleep routine and rest when you are tired
• Stay connected — regular contact with friends, family or local groups
• Keep up hobbies that use your other senses, such as music, audio books, podcasts, craft or gardening
• Attend your regular eye checks and low-vision appointments
• Make your home safer to reduce the risk of falls, for example by clearing clutter and using night lights

Diet and exercise

There is no special diet for Charles Bonnet Syndrome. Eating a healthy, balanced diet and staying active are good for your general health and for your eyes — especially if you have diabetes or heart and blood vessel conditions, which can affect your sight. Ask your doctor or pharmacist for advice on keeping your eyes and body healthy, and stay physically active in a way that suits you and feels safe.

Mental health and emotional wellbeing

It is very common to feel frightened, embarrassed or worried at first, and many people secretly fear they are developing dementia. That fear can lead to low mood, anxiety, poor sleep and avoiding other people. If you feel overwhelmed, low or hopeless, or if you have thoughts of harming yourself, contact your doctor, a local crisis line, or your local emergency number straight away — you deserve support and you are not alone. Talking to someone who understands the condition often brings huge relief.

Prevention

Charles Bonnet Syndrome cannot usually be prevented, because it is linked to sight loss itself. What you can do is protect your eyesight and reduce the impact. Regular eye checks, managing conditions like diabetes and high blood pressure, and keeping your glasses and low-vision aids up to date all help. If sight loss has already happened, good lighting and staying socially and mentally active may help reduce how often episodes happen.

Vaccines

There is no vaccine for Charles Bonnet Syndrome. Staying up to date with recommended vaccinations is still a good idea because infections and illnesses can make hallucinations more likely or more distressing.

Screening programmes

There is no screening programme for Charles Bonnet Syndrome. The best approach is to have regular eye checks as advised for your age and health, and to tell your doctor or optometrist straight away if you start seeing things that are not there.

Complications

If left untreated

• Ongoing fear and worry, sometimes leading to anxiety or depression
• Embarrassment that leads to silence, isolation and loneliness
• Avoiding going out or doing everyday activities
• Being wrongly assumed to have dementia or a mental illness
• A higher risk of falls if an unexpected image makes you jump or lose your balance
• Poor sleep if episodes happen at night

Long-term outlook

The outlook is generally hopeful. For many people, the images become less frequent and less troubling over time, especially once they understand what is causing them. Some people continue to have episodes, but with the right information and support they can live well with the condition. Charles Bonnet Syndrome does not damage your eyes further and it is not a sign that you are losing your mind.

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