What is Charles Bonnet Syndrome?
Charles Bonnet Syndrome is the experience of seeing (hallucinating) things following a significant loss of sight, regardless of the cause of that loss. It is not remembering an image clearly, it is literally seeing something that isn’t there.
Charles Bonnet Syndrome (CBS) is the brain’s response to the lack of visual stimulus; it is compensating for the lack of detail and input due to the change in sight. It is not known why some, not all people experience CBS. The person experiencing CBS might see something simple, such as a geometric pattern or mesh-like coverings, to something much more complex such as people moving around, strange faces, wild animals or distorted buildings to give but a few examples. The hallucinations do not come with sound or other sensations, but are purely silent and visual.
It is very important to note that CBS is entirely to do with loss or deterioration of sight and nothing to do with mental health problems.
For some ‘sufferers’, CBS can happen just once or twice, for others it can be a daily occurrence. Often the CBS activity decreases for the individual over time, with it eventually disappearing for good as the brain adjusts to the new level of sight, however this is not always the case and some sufferers never lose their CBS.
It is hard to establish how many people there are in the world with CBS. It is thought that up to 60% of people with significant sight-loss also experience CBS, so taking the RNIB’s estimate that more than two million people are living with sight loss that has a significant impact on their daily life, then over one million people could have CBS in the UK alone.
Why is it called Charles Bonnet Syndrome?
It is named after the first person known to have documented the phenomenon, a scientist and philosopher from the 1700s. Charles Bonnet realised what was happening to his Grandfather after he developed sight-loss some years after cataract operations. Bonnet wrote about his Grandfather’s sight-loss and visual hallucinations and made it clear in his writings that other than his eye disease, his Grandfather was of good health and sound of mind.
Why is it a problem?
CBS is not always a problem. We are using the word ‘sufferer’ here for ease but in occasional circumstances CBS can be enjoyable – for example some who experience CBS are fully aware their hallucinations are purely a result of their sight loss, the hallucinations themselves are relatively infrequent and present pleasant images. For others ‘sufferer’ is definitely the correct word and CBS can be frightening or confusing, particularly when:
- The sufferer does not know what they are experiencing and are worried it signifies a mental health issue such as dementia.
- The sufferer sees unpleasant, grotesque or scary things.
- The sufferer feels a loss of control — they don’t know when their CBS will start or finish and what they will see.
- For some sufferers their hallucinations can cause severe disorientation, for example ‘seeing’ their living room as another room entirely, or as the same room but with wildly different dimensions; the doorway might appear to be 10 metres away when in fact it’s within touching distance.
- For other sufferers it is an obstruction to their residual sight. A pattern might appear in front of their eyes all day and they cannot see past it.
NNAB Case Study: Doreen (all names have been changed)
Doreen is a client of the NNAB. She is 89 years old and has Macular Degeneration. She is registered as sight impaired — her detailed vision is missing but she can easily see large objects, for example if you were sitting having coffee with her, she could see you and describe some of your clothing, but she would not be able to see your face.
Doreen has had CBS for several years on a daily basis but does not see things all day. She finds her hallucinations come unexpectedly, often when she is relaxed. Doreen has both simple and very complex hallucinations; she repeatedly sees mesh coverings on anything in the room (including guests!) but has also seen animals within her house and very tall, distorted people climbing out of cupboards towards her when she was in bed at night.
How does she feel?
To begin with Doreen was very frightened, particularly by the people she hallucinated — although they were completely vivid, she knew they weren’t real and worried she was ‘losing her mind’. Doreen spoke to her doctor who unfortunately at that time was unaware of CBS and referred her for brain scans. However soon after this she found out through the hospital eye clinic that she was experiencing CBS.
Having found out what it was, Doreen was greatly reassured and following the eye clinic’s advice, she ‘talked, talked, talked about it.’ Doreen feels that simply knowing her experiences were CBS and being able to be open about it really helped, indeed she attributes it to stopping the complex hallucinations. Doreen now accepts CBS as part of her sight loss although the hallucination of people coming out of cupboards has definitely left its mark and she is anxious (years later) that it may reoccur. For Doreen, continuing to talk about CBS and find out more about it is an excellent way of helping to manage it.
Is there a cure for CBS?
As yet, no, it is still being researched and there is currently no medicine or treatment made specifically for CBS. However as shown in the case study above, measures can be taken to ‘diminish’ the feelings CBS can cause. Practical steps can also be taken to reduce the
longevity of a hallucination. Here are a few examples we have learned from our clients with CBS:
So many CBS sufferers attribute their hallucinations to a change in light, including opening their eyes upon waking up. Poor or bright lighting seems to be a real trigger for some, with hallucinations frequently reported first thing in the morning or at dusk. A change in lighting can therefore be helpful; Elizabeth repeatedly saw her hallucinations when she woke up at night, she now sleeps with a lamp on and this has stopped them occurring. So, simply putting a light on or off or moving to a different room may be enough.
Here is a suggested eye exercise from the Macular Society:
Imagine two points about a metre (3ft) apart on a wall in front of you. Sit or stand about a metre and a half away and, without moving your head, -look from one point to the other once every second or faster for 15 to 30 seconds, followed by a break of a few seconds. Hold your eyes open during the
James gets the same hallucination, always at night time when he is relaxed and drowsy. His CBS starts off pleasantly, but changes into something uncomfortable to see. At the point which his hallucination becomes unbearable to him, he finds that simply focusing on a familiar object within the room and ‘re-engaging with the real world’ is enough for him to ‘break’ the hallucination.
Margaret sees playing cards everywhere in the room, for every blink of her eyes, a card disappears until they are all gone.
Address the hallucination:
Some sufferers actively talk or seek to touch their hallucination. Mary saw a smiling crocodile in her lounge, she reached out to pat it on the nose and it disappeared. Alice used to see small Victorian children in her sink when she was trying to brush her teeth at night! Alice would flap her hand at them and tell them in the nicest possible manner to go away and they duly did!
Stressful situations and medical conditions:
There is a link for many with CBS between stress and upheaval and the level of their CBS activity. Most stressful situations cannot be avoided however knowing upfront that a worsening of CBS might be a side-effect could help. Infections and other problems with your general health can also make CBS worse. If you need to go to hospital, ensuring hospital staff know about your CBS, having visits from friends and loved ones and having a comforting distraction to hand such as radio or audio books might play their part in reducing the frequency or unpleasantness of the CBS.
Taking a CBS advice booklet with you when going into hospital, respite care etc. could come in handy for those around you. See the end of this article for details on where to get more information on CBS.
Don’t go it alone:
Like Doreen said: talk, talk, talk about it. If you are worried about being disbelieved by friends or family at first, you could always talk to your eye clinic or a sight-loss charity, they will almost certainly know about CBS and can give you more information and even put you in touch with other sufferers.
If you live in Norfolk, get in touch with the NNAB (Norfolk & Norwich Association for the
Blind). The NNAB offer a Community Worker service and can visit you in your own home to talk about all aspects of your sight loss. The Community Workers have spoken to hundreds of people with Charles Bonnet Syndrome and have a really good understanding
of how it can affect people.
There is plenty of additional Charles Bonnet information available and details of some of the organisations that can help are included below.
The Norfolk & Norwich Association for the Blind (NNAB):
Tel: 01603 629 558
The NNAB would like to thank Dr. Dominic ffytche, Clinical Senior lecturer at the Institute of Psychiatry, Psychology and Neuroscience, King’s College London, for help with this article.