Charles Bonnet Syndrome

Overview

Charles Bonnet syndrome (CBS) is a condition where a person sees vivid pictures, shapes, or people that are not really there. This is called a visual hallucination. It happens most often in people who have lost some or all of their sight. The person usually knows the images are not real, even if they look very clear. CBS is not a mental illness and it is not a sign of dementia.

CBS is thought to be more common than many people realise among people with significant vision loss. It is often not reported because people may feel embarrassed or worry that it means dementia. Exact numbers are hard to know.

It most often affects older adults with eye conditions such as age-related macular degeneration (a common eye condition that affects central vision), glaucoma (damage to the eye nerve), or diabetic eye disease. It can also happen in younger people and children who lose vision, though this is less common.

Symptoms

Common symptoms

• Seeing patterns, shapes, colours, or lines that are not there
• Seeing people, faces, animals, or scenes that look real
• Images may be clear and detailed, or blurry and simple
• Hallucinations often appear in low light, when tired, or when alone
• They may last seconds or minutes, and may come and go
• The person usually knows the images are not real
• The experience can be calming, strange, upsetting, or embarrassing
• Hallucinations are usually only visual. If you hear, smell, or feel things that are not there, tell your doctor.

Symptoms in children

• CBS is rare in children, but it can happen when a child has vision loss.
• A child may describe seeing strange pictures, people, or animals.
• Children may not understand that these images are not real and may feel scared.
• They need gentle reassurance and an eye and health check.

Symptoms in older adults

• CBS is most common in older adults, especially those with age-related eye disease.
• Hallucinations may be more noticeable in low light, when tired, or after a change in vision.
• Older adults may worry that they are developing dementia or a mental illness.
• Reassurance, good eye care, and support can reduce distress.

Causes

Main causes

• Vision loss: when the eyes send less information to the brain, the brain may fill in the gaps with images.
• Damage to the eye or visual pathway from conditions such as macular degeneration, glaucoma, cataracts, diabetic eye disease, or stroke.
• Sensory deprivation: when there is less visual input, the brain can create its own pictures.

Risk factors

• Older age
• Significant vision loss in one or both eyes
• Low light, tiredness, stress, or being alone
• Recent changes in vision or eye treatment
• Social isolation

When to see a doctor

See a doctor urgently if:

• You have new visual hallucinations for the first time
• Your vision suddenly changes
• You have eye pain, redness, or a severe headache
• The hallucinations are very distressing or you feel unsafe
• You have confusion, fever, weakness, numbness, trouble speaking, or a head injury. Call your local emergency number.

Book a routine appointment if:

• You have known vision loss and start seeing things
• The hallucinations worry you or affect daily life
• You want help understanding what is happening
• You need support with coping, eye care, or safety at home
• You have known CBS and your symptoms change or become more troubling

Diagnosis

There is no single test for CBS. A doctor makes the diagnosis by talking with you about what you see, your vision history, and your health. They will also check for other causes of hallucinations, such as eye problems, brain or nerve conditions, medicines, or infections.

Tests that may be done

• A detailed eye examination and vision test
• Questions about the hallucinations: what you see, when it happens, how long it lasts, and whether you know it is not real
• A neurological examination (a check of the brain and nerves)
• A review of your medicines
• Blood tests or brain scans in some cases to rule out other causes

What to expect at your appointment

You may be asked to describe the images in detail. It can feel strange, but it helps the doctor. You may be referred to an eye specialist, a doctor who cares for older adults, or a brain and nerve specialist. Most people do not need lots of tests if the pattern is typical and the eye exam explains the vision loss.

Treatment

There is no cure for CBS, but many people find it becomes less troubling over time. Treatment focuses on checking and treating eye problems, improving lighting, reassurance, and coping strategies. For severe distress, specialists may discuss other options case by case.

Self-care at home

• Keep rooms well lit, especially at night
• Use your glasses or low vision aids as advised and have regular eye checks
• Rest when tired and reduce stress where possible
• When hallucinations start, try blinking, looking away, moving your eyes, turning on a light, or changing what you are doing
• Tell a trusted person so you are not alone with it
• Ask about support groups for people with vision loss or CBS

Medical treatments

No specific medicine is approved for CBS. Doctors may treat underlying eye conditions. In rare cases of severe, distressing hallucinations, a specialist may consider medicine, but this is decided carefully and is not a first-line treatment. Always discuss benefits and risks with your healthcare provider.

When is surgery considered?

Surgery is not a treatment for CBS itself. If a treatable eye condition is causing vision loss, your eye specialist may discuss surgery or other eye treatments. This may improve vision but does not always stop CBS.

Living with this condition

CBS can be unsettling, but it often becomes less frequent or less bothersome with time. Keeping lights on, using distraction, and reminding yourself that the images are not real can help. It is okay to tell family and friends so they can support you.

Lifestyle tips

• Keep regular eye appointments
• Make your home safer with good lighting and clear paths
• Stay connected with friends, family, or local groups
• Plan activities you enjoy
• Avoid too much tiredness and stress
• If hallucinations distract you, avoid driving or using machinery until you have spoken to your doctor

Diet and exercise

There is no special diet for CBS. A healthy, balanced diet and regular movement are good for general health and wellbeing. Ask your healthcare provider about exercise that is safe for you, especially if you have vision loss or balance problems.

Mental health and emotional wellbeing

CBS can cause anxiety, fear, embarrassment, or worry about dementia. These feelings are common. Talking to a doctor or counsellor can help. If you feel very low or have thoughts of harming yourself, contact your local emergency number or a local crisis support service right away.

Prevention

CBS cannot always be prevented because it is linked to vision loss. Looking after your eyes, having regular eye checks, and treating eye conditions early may help protect your vision. If you notice hallucinations, getting help early can reduce worry.

Vaccines

There is no vaccine for Charles Bonnet syndrome.

Screening programmes

There is no screening test for CBS. Regular eye checks are important, especially if you have a condition that can affect your vision.

Complications

If left untreated

• Ongoing distress or anxiety
• Embarrassment and social isolation
• Falls or accidents if vision loss makes moving around unsafe
• Worry that it is dementia or mental illness
• Rarely, severe distress or depression

Long-term outlook

The outlook is often good. Many people find the hallucinations become less frequent or easier to live with over time. Some people continue to have them, but support and coping strategies can help. CBS does not mean you are losing your mind, and it is not dementia.

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