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Medical Charles Bonnet Syndrome: Non-Psychotic Visual Hallucinations

  1. Sep 22, 2005 #1
    "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. These can be enjoyable or sometimes upsetting.
    A Swiss philosopher named Charles Bonnet first described this condition in the 1760 when he noticed his grandfather who was blinded by cataracts describing seeing birds and buildings which were not there. Although the condition was described very early 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 out of fear of being thought of as mentally ill.

    Who's affected?

    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.

    What causes 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 that shows that all this constant seeing 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, 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.

    Don't only 'mad' people see things?

    It is fairly normal for people who start to see things to worry about there being something wrong with their minds. Seeing things is often a sign of mental illness and the threat of Alzheimer's can often be a worry. People often keep quiet about their hallucinations for fear that people will think they are losing their minds. It is important to realise that failing eyesight and not any other mental problems normally causes CBS.
    There are other medical problems, which can cause people to see things, Parkinson's disease, Alzheimer's, strokes and other brain conditions which effect 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.
    Another difference between the hallucinations, which people with mental health problems and people with CBS have, is that in CBS people quickly learn that the hallucinations although interesting are not real. On the other hand, people with a mental illness have trouble telling the difference between their fantasies and reality and will often come up with complicated explanations for the things they are seeing (sometimes called a delusion). If you think you are having Charles Bonnet Syndrome hallucinations then tell your GP about them.

    What kind of things do people see?

    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 e.g. cows in a field or unreal e.g. pictures of dragons.
    Firstly, there are the hallucinations of patterns and lines, which can become quite complicated like brickwork, mosaic or tiles.
    Secondly, there are more complicated pictures of people or places. Often whole scenes will appear such as landscapes or groups of people, which are sometimes life size and other times tiny people and tiny things. These pictures appear out of the blue and can carry on for a few minutes or sometimes several hours... "

    Charles Bonnet Syndrome - Eye Conditions - Neville Clarence Technologies
    Address:http://www.nctec.co.za/eye_conditions/charles_bonnet_syndrome.html [Broken]

    A more fanciful report:

    Charles Bonnet Syndrome
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Sep 27, 2005 #2
    People who develop macular degeneration get this, and think they are going mad, and won't discuss it. The hallucinations have many similar formats, once people did start discussing them, they found out there is great similarity in routine geometric phenomenon seen by people who are blinded by this disease.
  4. Sep 28, 2005 #3
    This is too bad since the fear you are going mad is a good sign that you're not: you have insight into the fact these things aren't real or normal. This is one reason I like to disseminate as much info about the various neurologically based hallucinations as I can.
    I run into mention of the notion that there are fundamental geometric shapes hardwired into the brain's visual system, but I haven't read anything detailed about it.
  5. Sep 30, 2005 #4
    There is a writer fairly well known, who chronicled his descent into blindness from macular degeneration. My father had just spent 45 minutes detailing these target patterns, and circular structures he would see, trying to see the television around the edges of his visual field, since the center is what is destroyed in macular degeneration. The next day I ran across the writings of this author, and he described the same structures my Dad had discussed the day before. There is always google.
  6. Oct 6, 2005 #5
    That's weird, I wonder doesn't everyone occasionally see geometric patterns dancing around when they turn out the lights and are going to bed?
  7. Oct 6, 2005 #6
    A recent thread about that:

    Random light with eyes closed? - Physics Help and Math Help - Physics Forums
  8. Apr 2, 2010 #7
    I want to know further Charles Bonnet Syndrome, I have an assignment on it :(
  9. Apr 2, 2010 #8


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    Staff: Mentor

    Well then read the information above from this 5-year-old thread (!), and then do a Google search. I just did the Google search and got LOTS of good information.

    That's how you do a schoolwork assignment. :smile:
  10. Apr 2, 2010 #9
    Yeah, I have been googling but couldn't complete my assignment yet! Anyways thnx!
  11. Apr 3, 2010 #10
    Thanks for the share. It was a good read :)
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