When you lose your sight, your brain, starved of visual information from your eyes, may try to fill in its sensory gaps by creating new fantasy patterns or pictures in your mind. When this happens, you may experience hallucinations; this is a recognized condition called Charles Bonnet Syndrome (CBS). CBS tends to start in the weeks and months following a big deterioration in your sight but can develop at any time.
Hyenas and Landscapes
One of the strangest occurrences when losing my sight was a series of vivid hallucinations I experienced after a difficult period in which I had my left eye enucleated (totally removed) and suffered a further series of detached retinas in my right eye. In effect, I became dark-blind for a period of six weeks, and during this time, I started to see things that defied even what I thought of as my own weird imagination.
Can you imagine looking at a Spotted Hyena staring fixedly out of the window in an old Rajasthan hill fort, such as Jodhpur’s Mehrangarh Fort, or looking down from an eagle’s viewpoint of the ground far below you and possessing the ability to zoom your sight down through the clouds with remarkable detail to observe scenes in the landscape below; or to examine the wood grains in a cut piece of oak with remarkable clarity as you follow their horizontal pattern! It was a strange time, especially as I have never visited Rajasthan!
Although these visions or hallucinations were graphic in their detail and slightly disturbing in their occurrence, I knew that what I was seeing wasn’t real and that it was my brain playing tricks. I enjoyed trying to explain what I was experiencing to my family, they probably thought I was mad, and no doubt in front of me were rolling their eyes upwards in that annoying way all older teenagers are capable of. Especially when re-assessing their parental choice amongst the wider pantheon of their friend’s fathers. Indifferent to their discomfort and mortification, I continued describing what I saw, having never experienced anything like this before!
Photos by Melissa van Niekerk, Nik Ramzi Nik Hassan and Andrey Haimin on Unsplash.
Only later did I find out that the trauma of losing total sight in my left eye and the temporary sight loss through heavy bandaging in my right eye was probably triggering a recognized condition called Charles Bonnet Syndrome (CBS). It is not uncommon in about 20% of people who lose sight or are deprived of light sensory input.
The nature of the hallucinations you experience with CBS normally falls into two distinct categories:
- simple repeated patterns or shapes, such as grids or brickwork patterns
- complex hallucinations of people, objects, and landscapes.
Do the hallucinations last?
My period of enforced dark blindness only lasted a few weeks before partial sight in my right eye reappeared once the bandages were removed permanently, and I have never returned to that extent. I believe that in those who are perpetually dark blind, the hallucinations recede in intensity and frequency with time as the brain probably readjusts to the loss of input from the eye’s optic nerves.
What causes CBS?
I have lifted the following information from the CBS guidance referenced above, and it seems through their research that 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 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 that processes what you are seeing. This area is called the visual cortex. The visual pathway is the term used to describe the route the light takes from being detected by the eyes to being processed in the brain. 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 your sight, however, 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?
Probably when you think you are seeing a hyena calmly staring out am open window in a Rajasthan fort tower!
How will you know you are going mad? When that same hyena starts talking to you!
CBS hallucinations are rarely connected with other sensory symptoms such as smell, noise or touch. If you hear voices repeatedly urging you to kill all squirrels or any other satanic-sounding message, then you will know you definitely have a problem greater than CBS!
Photo by Lee Jiyong on Unsplash
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. I wish I had known about the syndrome before experiencing it. It would have been of some small advantage in explaining what I later experienced.
Talking about what I was seeing with my family and companion helped me put the symptoms into context, as you are likely to be aware that it is attributable to any recent sight loss and your brain adjustment to its new normal.
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