About Charles Bonnet syndrome
Charles Bonnet syndrome (or CBS for short) is a term used to describe the situation when people with sight problems start to see things which they know aren't real. Sometimes called 'visual hallucinations', the things people see can take all kinds of forms from simple patterns of straight lines to detailed pictures of people or buildings.
A Swiss philosopher named Charles Bonnet first described this condition in 1760 when he noticed that his grandfather, who was almost blind, saw patterns, figures, birds and buildings which were not there. Although the condition was described almost 250 years ago, it is still largely unknown by ordinary doctors and nurses. This is partly because of a lack of knowledge about the syndrome and partly because people experiencing it don't talk about their problems from fear of being thought of as mentally ill.
Charles Bonnet syndrome affects people with serious sight loss and usually only people who have lost their sight later in life but can affect people of any age, usually appearing after a period of worsening sight. The visual hallucinations often stop within a year to eighteen months.
Causes of Charles Bonnet syndrome
At the moment little is known about how the brain stores the information it gets from the eyes and how we use this information to help us create the pictures we see. There is some research which shows that, when we see, the information from the eyes actually stops the brain from creating its own pictures. When people lose their sight, their brains are not receiving as many pictures as they used to, and sometimes, new fantasy pictures or old pictures stored in our brains are released and experienced as though they were seen. These experiences seem to happen when there is not much going on, for example when people are sitting alone, somewhere quiet which is familiar to them or when they are in lying in bed at night.
Charles Bonnet syndrome and mental health
Seeing things which aren't there can sometimes be frightening. Some people may worry that seeing things is a sign of mental health problems or of conditions such as Alzheimer's. They may be worried about this so much that they don't tell their GPs, families or friends what is happening. It is important to realise that CBS is caused by failing eyesight and not any other health problems.
There are other medical problems which can cause people to see things: Parkinson's disease, Alzheimer's, strokes, serious mental illness and other brain conditions which affect that part of the brain concerned with seeing.
Having CBS does not mean that you are more likely to develop any of these other conditions.Usually people with CBS are aware that their hallucinations, although vivid, are not real. CBS hallucinations only affect sight and do not involve hearing things or any other sensations. People with CBS do not develop complicated non-medical explanations about the cause of their hallucinations (sometimes called 'delusions'). If you think you are having Charles Bonnet syndrome hallucinations, tell your GP about them. You may find it useful to take a copy of this webpage along with you to show to your doctor.
Common hallucinations
There seem to be two different kinds of things people see. Both of them can be black and white or in colour, involve movement or stay still, and they can seem real - such as cows in a field, or unreal - such as pictures of dragons.
Firstly, there are the hallucinations of patterns and lines, which can become quite complicated like brickwork, netting, mosaic or tiles.
Secondly, there are more complicated pictures of people or places. Sometimes whole scenes will appear, such as landscapes or groups of people, which are sometimes life-size, and at other times are reduced or enlarged in size. These pictures appear 'out of the blue' and can carry on for a few minutes or sometimes several hours.
Many people begin to recognise similar things appearing in their visions such as distorted faces or the same tiny people in particular costumes.
Generally the pictures are pleasant although the effects can be scary.
Effects of the hallucinations
Sometimes the complicated pictures can make it difficult to get around. For example, streets and rooms may have their shape changed or brickwork and fencing appear directly in front of you making it difficult for you to judge exactly where you are and whether you can walk straight ahead. One gentleman describes how, approaching the top of the stairs, he had a vision of being on top of a mountain, and had considerable problems getting down the stairs. Good knowledge of your surroundings can help overcome this particular problem.
The complicated pictures can sometimes be a little scary. Although the visions themselves may not be of anything frightening, it is disturbing to start seeing strangers in your home or garden. People often overcome this by getting to know the figures in their visions. Another man describes how, when he wakes up in the morning, he says to the figures he is seeing: "Right, what have you got in store for me today?" This allows him to have some control over the way he feels about his seeing things.
Prognosis
For most people, just knowing that it is poor vision and not other health problems that cause CBS is the best treatment, helping people to understand and come to terms with their hallucinations. Generally these experiences will disappear after about a year or eighteen months but, of course, this will not happen for everyone with this problem. For those with serious disturbing hallucinations, a number of medications are available. Unfortunately, however, none are effective for everyone.
One way of dealing with visions, when they occur, is to try to change things to see if this will help them disappear. For example, if they happen in the dark, try switching a light on or if they happen in the light, try switching the light off. If you are sitting down when they happen, try standing up. Some people find that moving their eyes helps (eg from left to right or up and down).
Sometimes talking over feelings with a counsellor, psychologist or psychiatrist can help provide people with ways of coping with the visions. If you are having problems with yours, talking to your GP may be a good way to find some help. Although CBS is not connected to mental health problems, the professionals in this field are the expert at helping people deal with hallucinations. If you are very distressed by your hallucinations, then your GP may want to refer you to the local mental health team.
You may want to think about contacting RNIB's Emotional Support Telephone Service.
What next
Talk to someone
The RNIB Helpline is your direct line to the support, advice and products you need. We'll help you to find out what's available in your area and beyond, both from RNIB and other organisations.
Whether you want to know more about your eye condition, buy a product from our shop, join our library, find out about possible benefit entitlements, be put in touch with a trained counsellor, or make a general enquiry, we're only a call away.
RNIB Helpline
Telephone: 0303 123 9999
Email: helpline@rnib.org.uk
We are ready to answer your call Monday to Friday 8.45am to 6.00pm and Saturday 9.00am to 4.00pm. Outside these times leave us a message and we'll get back to you as soon as possible.
Unfortunately, RNIB can only answer email enquiries from the UK. But you may find an organisation for people with poor sight in your country through our organisations database.
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Join our discussion forums - share your ideas with others and have your say about the issues that affect you.
Get information
RNIB's guide to Adapting to sight loss offers ideas for people with sight problems on making life easier and ways of getting the most out of life.
You may also find the following useful:
Further reading
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Tuenisse et al; Visual hallucinations in psychologically normal people: Charles Bonnet Syndrome; The Lancet; vol347; March 23; 1996
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Menon GJ, Rahman I, Menon SJ, Dutton GN. Complex visual hallucinations in the visually impaired: the Charles Bonnet Syndrome. Surv Ophthalmol 2003; 48: 58-72.
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ffytche DH. Visual hallucinations and the Charles Bonnet Syndrome. Current Psychiatry Reports 2005; 7: 168-179.
Useful contacts
At the moment RNIB is not aware of any specialised support group for people affected by Charles Bonnet. However, there is a lot of more general support for people affected by serious sight loss.
The Partially Sighted Society is able to give advice on coping with sight loss and can be contacted at the:
Partially Sighted Society
7-9 Bennetthorpe
Doncaster
South Yorkshire
DN2 6AA
Telephone : 0844 477 4966
For more information on Charles Bonnet syndrome please contact:
Dr Dominic ffytche
Senior Lecturer
Centre for Neuroimaging Sciences
Institute of Psychiatry PO89
De Crespigny Park
Denmark Hill
London
SE5 8AF
Telephone: 020 3228 3064 (voicemail)
Email: d.ffytche@iop.kcl.ac.uk
About this guide
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Last updated October 2008
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