Charles Bonnet syndrome (CBS) is a common condition among people who’ve lost their sight. It causes people who have lost a lot of vision to see things that aren’t there – medically known as having a hallucination.
What is Charles Bonnet syndrome?
Charles Bonnet syndrome (CBS) causes people with sight loss to see images that aren’t there. Medically, these are known as hallucinations. CBS hallucinations are caused by sight loss and are not a sign that you have a mental health problem. The amount of sight loss that people with CBS have can vary.
The types of hallucinations people with CBS may experience fall into two main areas:
simple repeated patterns or shapes, such as grids or brickwork patterns or colours
complex hallucinations of objects, such as people and landscapes.
CBS hallucinations are silent and do not involve any of the other senses. You cannot hear, smell or touch the images. Although they can be disturbing or frightening, people are usually aware that what they are seeing isn’t real.
The hallucinations usually get less frequent with time, although may not stop completely. A study found that it is not unusual to still have hallucinations even five years after they first started. There may come a time when the hallucinations stop, but they may come back if your sight gets worse. Everyone is different in their experience CBS and for some people the hallucinations remain with them intermittently throughout life.
Who develops CBS?
CBS occurs in people who have varying amounts of sight loss from any eye condition. As sight loss is more common in older people, many people who have CBS also tend to be older. However, anyone of any age may develop CBS following sight loss.
It’s difficult to know how many people in the UK have CBS because often people are unaware that sight loss can cause hallucinations. They think they might be developing a mental health condition so don’t always want to tell doctors that they are experiencing hallucinations.
Research suggests that about one in five adults who experience sight loss develop CBS. This means that at least 1 million adults in the UK are living with CBS. Research has only just begun into CBS in children. Children with sight loss are just as likely to develop CBS as adults but they have never been included in research until now. This means the number of people living with CBS is actually higher. It’s not yet known why some people with sight loss get CBS and some people don’t, but if you have an eye condition which might cause sight loss, it’s helpful to know about CBS so that you are prepared if it does occur.
What causes CBS?
CBS is caused by loss of vision and the way your brain reacts to this loss. Exactly how sight loss leads to hallucinations isn’t really known, but research is slowly revealing more about how the eye and the brain work together.
When your sight is good and you are seeing real things around you, the images are detected by the retina (the light sensitive layer at the back of the eye) and signals are sent via the optic nerve to the area of the brain called the visual cortex. The route the light takes from being detected by the eyes through to being processed in the brain is known as the visual pathway.
Any eye condition that causes damage to any part of the visual pathway can cause sight loss. If your visual pathway works well your eyes stop the brain from creating its own pictures. When you lose sight, your brain isn’t receiving as much information from your eyes as it used to. Your brain can sometimes fill in these gaps by creating new fantasy patterns or pictures. When this happens, you experience these pictures as hallucinations. CBS tends to start in the weeks and months following a big deterioration in your sight but can develop at any time.
How will I know if I have CBS?
It’s natural to be worried, confused or frightened when you see things that aren’t really there. You may be concerned that seeing things is a sign of a mental health problem, or you might think that you have dementia, until you know what’s happening. CBS is caused entirely by sight loss and the hallucinations aren’t a sign of any other health problem. If you have lost sight due to any eye condition and you start to see things that aren’t there, then you may have CBS.
There isn’t one specific test that your doctor can do to find out if you have CBS. Your doctor will want to rule out other causes of hallucinations, usually by talking with you and in some cases, carrying out tests. If there are no signs of any other conditions that might be causing your hallucinations, and you have recently lost some sight, then it’s most likely that you have developed CBS.
There are some medical conditions, such as Parkinson’s disease, Alzheimer’s disease, strokes, serious mental illnesses, and other brain conditions, that can affect the parts of the brain concerned with seeing and may cause some people to hallucinate. Sometimes, if you have sight loss and one of these conditions as well, it can make your hallucinations more frequent. It’s important to remember that having CBS doesn’t mean you’re more likely to develop any of these conditions.
CBS hallucinations are different from the hallucinations caused by other conditions. CBS hallucinations only affect your sight, which means that you don’t hear, smell or feel things that aren’t there. Usually, with CBS you’re aware, or can learn to recognise, that what you’re seeing isn’t real even though it’s very vivid.
People with CBS don’t develop any complicated thoughts (delusions), or ideas about why they are seeing things. Even though you may see images which are disturbing or frightening, you would not think that the people or animals you are seeing want to harm you.
If you suddenly find that you’re seeing a pattern, person, animal, building or a landscape that you know is not really there, then don’t be afraid to tell your GP, ophthalmologist (eye doctor) or optometrist (optician), who should be familiar with CBS. You may find it useful to take a copy of this information along with you.
Even though there is no cure for CBS, letting people know that you have this problem or talking about it may offer you some peace of mind, especially if you are anxious about what you are seeing. You can read more about this in the section on “Managing your CBS” later in this publication.
What kinds of things might I see?
When you have lost a large amount of your vision it can be difficult to see everyday things, but your CBS hallucinations may be very detailed, and much clearer than your everyday vision. CBS hallucinations can be of almost anything – from simple patterns, shapes or colours, to vivid detailed pictures of people, animals, objects or buildings. The images appear very suddenly, lasting for just a few minutes or in some cases, several hours.
As mentioned before, the kinds of images you may see with CBS generally fall into two types: simple repeated patterns or shapes, or complex hallucinations of people, objects and landscapes.
You may have one type of hallucination more than another or have both types of hallucination at the same time or one after another.
Simple repeating pattern hallucinations
Your CBS hallucinations may be of patterns or shapes laid on top of everything you see or growing across any surface you look at. You may see grids or shapes or lines, which can be quite vivid in colour, for example, bright green dots surrounded by vibrant pink squares. You may also see brickwork or simple repeating patterns across your vision. People can also see patterns that look like a network of branches or roots from a tree.
Complex hallucinations
Your CBS hallucinations may be of more complicated things like faces, people, places, insects and animals. The faces may be distorted or grotesque and move up in front of you.
You may hallucinate entire scenes, such as landscapes with waterfalls, mountains or a garden full of flowers. At other times you may see a single person or animal, or groups of people. You may see people dressed in costume, like Edwardian families, Roman soldiers or small children in bonnets. The figures of people in your hallucinations may be life size, larger than life sized or very commonly, tiny.
At times, the hallucinations may fit with your surroundings such as seeing people working in your garden. At other times the hallucinations can appear very odd, such as double-decker buses in your kitchen. Sometimes the images can be totally unreal, like fantasy pictures of dragons or unicorns.
CBS hallucinations don’t usually include familiar people or past events that you may have experienced. Not all the images that you see are threatening or unpleasant, but of course, most people are frightened when they first start hallucinating.
Over time, the more you see the images, the more comfortable you may become with them. You may begin to recognise the same things appearing in your hallucinations, such as the same tiny people, or the same field of flowers.
Sometimes the hallucinations may be in black and white and at other times in colour. They may move or stay still.
Does CBS get better with time?
When you first develop CBS, your visual hallucinations may happen quite often; you may see images every day and for long periods of time. However, everyone has a different experience of CBS, for some people the hallucinations may get less frequent over a few months. They may eventually stop, but for others the condition may continue for years or lifelong.
If your hallucinations do stop, it’s possible that they may come back if you lose more sight. Many people also find that their hallucinations can come back or get worse if they are unwell with an infection, such as a bladder infection (also known as a water or urinary tract infection) or a chest infection. If you find that your hallucinations do come back or get worse, speak to your GP who can check for reasons such as infections.
You may also find that your hallucinations get worse when you are anxious, isolated or stressed. You can contact your GP if you are struggling with feelings of anxiety or stress or call our helpline so that we can offer emotional support, advice and information to help with your situation to reduce your stress, access befriending services and emotional support.
Is there any treatment for CBS?
Currently there is no medical cure for CBS, but this does not mean there is nothing that can be done to help. Sometimes just knowing that the condition is not a mental health problem, nor a symptom of another disease can help a lot. Knowing that CBS usually improves with time (even if it doesn’t go away completely) and having information on CBS as well as sharing your experiences with friends or family can also help. There are also ways to manage CBS that are described below.
Everyone with CBS should have a general health check to look for other factors that may be making the hallucinations worse. This includes ruling out memory problems and infections as well as thinking about the medication you are taking. Some medications given for other conditions may have side effects which make CBS worse. It is always worth checking with your GP if your medications may be making your CBS worse. There may be alternatives that you could take instead. It is important not to stop taking any prescribed medications without talking to your GP first.
Anticholinergics are a group of medications which can sometimes make hallucinations worse, especially in older people. They can be prescribed for lots of different health conditions including motion sickness, bowel and bladder problems. If you are taking more than one type of anticholinergic it can sometimes make your hallucinations worse. Some eye drops can also increase CBS.
If you have CBS, you’re likely to have very poor vision, or some amount of sight loss. Trying to make the most of the sight you have can help to make the hallucinations less frequent. This may mean making things bigger by using a magnifier, using brighter lighting, or using colour (contrast) to make things easier to see. A low vision assessment can explore these things with you. Your GP, optometrist or ophthalmologist can refer you to your local low vision service for an assessment. Wearing any spectacles your optometrist has prescribed for you is also important to help you make the most of the sight you have.
For those people with very troubling or distressing CBS there are medications that can be tried. There’s no proven drug you can take to stop CBS hallucinations. Some drugs prescribed for other conditions, such as epilepsy, Parkinson’s disease, dementia and mental health problems have been tried to help manage CBS hallucinations. However, all these drugs are very strong and can have serious side effects. Most people with CBS wouldn’t need them, but they may be useful for some people (if used carefully).
Managing your CBS
Hallucinations can be frightening, particularly when you’re also dealing with losing your sight. Although the hallucinations may not be of anything frightening, it’s natural to feel anxious and confused just by having the experience of a hallucination.
Talking about CBS
If your hallucinations make you anxious, you may feel like keeping them to yourself. However, even though there’s no cure for CBS, letting people know you have this problem or talking about it may help give you peace of mind.
Describing your hallucinations and how they make you feel may help you cope with them. Most people find that talking about their hallucinations with their GP, optometrist, ophthalmologist, family, friends or carers can help.
It can be helpful and reassuring to talk with other people experiencing CBS hallucinations. CBS Talk and Support groups are available through RNIB. These are befriending groups specifically for people with CBS. You can share and listen to others’ experiences which can help you feel less alone.
Family and friends can support those experiencing CBS hallucinations by allowing them to talk openly about what they are seeing. It’s helpful if you don’t ‘play along’ with the hallucination the person is seeing, but to instead, gently remind and reassure them that what they are seeing isn’t real.
Although CBS isn’t connected to mental health problems, professionals who work in the mental health field have a lot of experience in helping people deal with hallucinations. If your hallucinations become upsetting, your GP could refer you to the local mental health team for further help. Talking over your feelings with a counsellor, psychologist or psychiatrist may provide you with ways to reduce the anxiety the hallucinations may cause.
Dealing with the hallucinations
For most people there isn’t just one way to deal with their hallucinations, but there are a few things that you can try to do that may help.
Change what you are doing
Many people find that their hallucinations appear when they are sitting quietly without much occupying their mind. Putting the TV or radio on, or standing up and moving around, or going into a different room can sometimes make the hallucination disappear. Moving your head slowly from side to side, dipping your head at each shoulder may also help.
Change the lighting
If your hallucinations happen in dim light, then try opening the curtains, turning on a light or the television. Lighting conditions in certain rooms may also mean that you see the hallucinations more often in one room than another. For example, you may find that you rarely get your hallucinations in your garden or kitchen, but that you often see them in your living room. This may be because the kitchen and garden are much brighter and this is helping to control the hallucinations. If your hallucinations happen when there’s a lot of light, then switching off a light may also help.
Making sure that the lighting is the right level for your sight condition in all the rooms in your home will help you make the most of your sight and might help with your hallucinations.
Look directly at the image or reach out to it
Some people also find that looking directly at the image they are seeing or reaching out to touch it or brush it away causes it to fade.
Eye movements and blinking
Sometimes moving your eyes or blinking rapidly can also help.
A study has shown that a specific eye movement exercise may help. When a hallucination starts, look from left to right about once every second for 15 – 30 seconds, without moving your head. As a guide to how far to move your eyes, imagine two points about a metre (three feet) apart on a wall in front of you and look from one point to the other when standing about a metre and a half away (five feet). Your eyes should be held open during the movements. If the hallucination continues, have a rest for a few seconds and try another 15 – 30 seconds of looking left and right. If you’ve tried four or five times and the hallucination is still there, then it’s unlikely to work, but you may want to try again another time or when you have a different type of hallucination.
Relaxation or mindfulness
Some people find that their CBS hallucinations are worse when they’re tired or stressed. It is important to make sure you have enough sleep at night and have time to relax.
Familiarise yourself with the images
Sometimes it can help to get to know your hallucinations so that you become familiar with them. You may find that this means the hallucinations become less frightening and easier to cope with. This could mean you have some control over the way you feel about the images you are seeing.
Food supplements
The addition of real ginger or Omega 3 in your diet has been found to be helpful by some people but it is important that you check with your GP before trying this because this can interfere with some medications.
Is it too detailed to be real?
When you see something that is frightening or makes you unsure, ask yourself “Is this too detailed to be real?” The fact that the image is detailed and vivid compared with the way you usually see, is a clue that this is an hallucination. As well as these general points, here are a few more tips which may help you deal with certain types of hallucinations.
Dealing with hallucinations of space
Your hallucinations may change the shape of streets and rooms. For instance, your hallucinations might suddenly make it look like there is a wall or fence in front of you and you may have to check if this is real. This can make you lose confidence when walking around and it may take you longer to get out and about.
If you experience hallucinations like this, reach out and check the area around you before you move. Using a cane or walking stick to do this is useful. Moving slowly, feel around for what is real and what is not. Having a good knowledge of your surroundings can also help with these kinds of hallucinations.
Dealing with hallucinations of people
Hallucinations of people can be frightening, particularly if they’re inside your home. Often the images are of very small people or people in costumes, these can be easier to recognise as hallucinations than if the figure is in ordinary clothes. Having a good idea of when you’re likely to have real people visiting you will help in making you feel secure in your home or your surroundings.
Dealing with hallucinations of animals
Hallucinations of animals are also very common. Often people describe animals on their chairs or in their bed. Sometimes this can be very upsetting, especially if you aren’t keen on a particular type of animal.
You can try using touch to make sure that the animals are hallucinations, and sometimes reaching out towards the hallucination may cause them to disappear