Charles Bonnet Syndrome (CBS; Bonnet's Syndrome)

[Mighty_Emperor]

When the Vision Goes, the Hallucinations Begin
By SUSAN KRUGLINSKI
Published: September 14, 2004

One day a few years ago, Doris Stowens saw the monsters from Maurice Sendak's "Where the Wild Things Are" stomping into her bedroom. Then the creatures morphed into traditional Thai dancers with long brass fingernails, whose furious dance took them from the floor to the walls to the ceiling.

Although shocked to witness such a spectacle, Ms. Stowens, 85, was aware that she was having hallucinations, and she was certain that they had something to do with the fact that she suffered from the eye disease macular degeneration.

"I knew instantly that something was going on between my brain and my eyes," she said.

Ms. Stowens says that ever since she developed partial vision loss, she has been seeing pink walls and early American quilts floating through the blind spots in her eyes several times each week.

In fact, Ms. Stowens's hallucinations are a result of Charles Bonnet syndrome, a strange but relatively common disorder found in people who have vision problems. Because the overwhelming majority of people with vision problems are more than 70 years old, the syndrome, named after its 18th-century Swiss discoverer, is mostly found among the elderly. And because older people are more susceptible to cognitive deterioration, which can include hallucinations or delusions, Charles Bonnet (pronounced bon-NAY) is easily misdiagnosed as mental illness.

Many patients who have it never consult a doctor, out of fear that they will be labeled mentally ill.

"It is not a rare disorder," said Dr. V. S. Ramachandran, a neurologist at the University of California at San Diego, who has written about the syndrome. "It's quite common. It's just that people don't want to talk about it when they have it."

Researchers estimate that 10 to 15 percent of people whose eyesight is worse than 20/60 develop the disorder. Any eye disease that causes blind spots or low vision can be the source, including cataracts, glaucoma, diabetic retinopathy and, most commonly, macular degeneration. The hallucinations can vary from simple patches of color or patterns to lifelike images of people or landscapes to phantasms straight out of dreams. The hallucinations are usually brief and nonthreatening, and people who have the syndrome usually understand that what they are seeing is not real.

Nancy Johnson, a 72-year-old retired schoolteacher from San Diego whose left eye was removed because of cancerous tumors, says she is not bothered by the images she sees.

"I see little tiny geometric shapes that all fit together," Ms. Johnson said. "Like doodles in the margin of a notebook. It's sort of interesting and distracting, but it's not fearful."

But the experience can also be frightening. Ms. Stowens, for example, said the visions of monsters terrified her.

"I couldn't even speak, my heart was beating so fast," she said.

Many patients are relieved to hear that what they are suffering from is simply a vision problem, said Dr. William O'Connell, a low-vision specialist at the State University of New York College of Optometry who has seen scores of patients with Charles Bonnet syndrome.

"I've had patients tell me, 'I thought I might be getting a brain tumor,' '' he said. "Or 'I thought I might be having a stroke,' or 'I thought I might have Alzheimer's.' "

Experts say that medication offers no relief to Charles Bonnet patients, and that in fact there is little that they can do to stop the hallucinations, besides blinking, brightening the light in a room or making other changes in the environment.

In some ways, researchers say, the hallucinations that define the syndrome are similar to the phenomenon of phantom limbs, where patients still vividly feel limbs that have been amputated, or phantom hearing, where a person hears music or other sounds while going deaf. In all three cases, the perceptions are caused by a loss of the sensory information that normally flows unceasingly into the brain.

In the case of sight, the primary visual cortex is responsible for taking in information, and also for forming remembered or imagined images. This dual function, Dr. Ramachandran and other experts say, suggests that normal vision is in fact a fusion of incoming sensory information with internally generated sensory input, the brain filling in the visual field with what it is used to seeing or expects to see. If you expect the person sitting next to you to be wearing a blue shirt, for example, you might, in a quick sideways glance, mistakenly perceive a red shirt as blue. A more direct gaze allows for more external information to correct the misperception.

"In a sense, we are all hallucinating all the time," Dr. Ramachandran said. "What we call normal vision is our selecting the hallucination that best fits reality."

With extensive vision loss, less external information is available to adjust and guide the brain's tendency to fill in sensory gaps. The results may be Thai dancers or monsters from a children's book.

"The most interesting thing to me," Ms. Stowens said of her syndrome, "is that this brain of mine keeps telling me things I don't want to know."

http://www.nytimes.com/2004/09/14/science/14eyes.html

This is the same thing as discussed by Paul Devereux in FT184:46-49 - macular degeneration.

 

[escargot]

I used to work on the local Head & Neck Unit where there were plenty of patients with macular degeneration but I never came across this. Must be because, as pointed out in the article, patients are afraid of talking about hallucinations.

A recent, I think Guardian article described an elderly chap who rather enjoyed the vision of a naked woman which strolled into his lounge each evening.

 

[Anonymous]

Interesting.
I have, for some time now, been seeing brown tabby cats in the corner of one of my eyes where I get a disturbance from a detatching retina. I'm developing a cataract in the same eye.
Eyesight problems are wierd indeed.

 

[_Lizard23_]

My mum had a stroke a couple of years ago now and is now registered blind. She can still see well enough to get around but has a HUGE blind spot slap bang in the middle of her visual field.

I described the symptoms of Charles Bonnet Syndrome to her after that FT article, as we were discussing her visual problems, and she was extremely relieved as she has been seeing things ... people dressed in overalls jumping over the front fence etc and was quite concerned for her sanity, but obviously never told anyone about it for that very reaon, daft old thing.

 

[Mythopoeika]

My mum has macular degeneration in one eye. I hope she doesn't see this sort of thing - she's a bit of a prude!

 

[Leaferne]

Is there any way of preventing macular degeneration while you're still relatively young?

 

[Anonymous]

I don´t know. If I end up in some old folks home tied to a wheelchair or bed, I would like if I hallucinated about naked women running around. Though with my luck it will probably be American quilts.

 

[escargot]

How about American women decently covered by quilts?

There's loads about macular degeneration on t'internet.

I wonder if the peeps on here who've talked about 'seeing' things like shadow people and fleeting 'corner of the eye' figures are suffering from this.

Having had a small but frightening blindness scare a few years ago (temporary patch blindness - turned out to be painless migraine!) I would urge anyone with symptoms to get them checked out. You never know.

Stella, tabby cats don't seem too disturbing. I'm relieved for you.

The BF's father had a detached retina for some years, then during a DIY accident involving a blow to the head it seemed to re-attach and his sight came back!
Dunno if he had any hallucinations though and he died before I met the BF so I can't ask him.

 

[Mighty_Emperor]

Earlier report:

Ghosts and witches on the brain

By Roger Highfield
(Filed: 06/11/2002)

The brain is a knowledge-gathering machine that carries out endless abstractions to form concepts, whether of a car, a line or falling in love. However, witches and fairies also lurk within it - along with more ghosts than can be seen at a Deathday party. These have been revealed by studies of hallucinations suffered by people who are losing their sight.

They are called Charles Bonnet hallucinations, after the Swiss naturalist who reported his grandfather's strange experiences and later went on to suffer the hallucinations himself. Dominic ffytche, of the Institute of Psychiatry in London, has studied many of these patients. "The hallucinations tend to be brief - lasting a few seconds or minutes - re-appearing after hours, days, months or even years. The experiences may be frightening, but with time most sufferers recognise them as hallucinations and learn to ignore them."

Strikingly, ffytche found patterns in these visions. Rather than witnessing anything and everything, the patients report apparitions that usually fall into a handful of categories, including distorted faces and costumed figures. "I'm sure ghosts, fairies and witches all relate in some respect to these disembodied hallucinations," he says.

Ghosts are among the categories. One patient described how a friend working in front of a tall privet hedge suddenly disappeared, as if he had suddenly put on a cloak of invisibility. "There was an orange peaked cap bobbing around in front of the hedge and floating in space by its own devices."

There are also ghouls. The disembodied or distorted face of a stranger with staring eyes and prominent teeth is seen by about half of all patients, sometimes only in an outline, cartoon-type form. The faces "are often described as being grotesque, or like gargoyles".

In the hallucinations, objects or people often appeared much smaller than usual, but sometimes were much larger (micropsia and macropsia). Could these distortions be linked to sightings of the little people and giants?

One patient described "two half heads joined like Janus", which sounds rather like what Harry Potter encountered, in his first adventure, at the back of Quirrell's head, where he gazed at a second face, the most terrible he had ever seen.

Another patient seemed to catch a glimpse of the dreaded Dementors: some of the faces conjured up by his failing eyesight have blank eye sockets with "expressions [that] are all evil and malevolent".

As well as random patterns and geometrical forms, ffytche's patients also saw serene landscapes and vortices. Near-death experiences could be activating the same brain areas that produce these hallucinations, he speculates.

Reassuringly for the patients, these figments are not a sign of madness. These phantoms appear when vision deteriorates to a certain point, usually as a result of eye diseases such as age-related macular degeneration, glaucoma and retinitis pigmentosa.

As the brain is starved of sufficient information from the eyes, it compensates with abnormally increased activity and conjures up hallucinations from the random firing of nerve cells. "You get the same phenomenon in patients who have had both eyes removed," he says. "When there is no information coming in, the brain is idle, cells are firing away and producing these stereotyped categories of hallucination."

Using a scanner, ffytche has observed that the thin rind on the back of the brain, where vision is processed, is active during these hallucinations, just as it is when a sighted person has his eyes open.

But where did the gargoyles come from? Ffytche points out that one part of the brain - the lateral occipital region - alerts us to the possibility that what we are looking at might be a face. This region detects a face's component features - the eyes, nose lips and chin, for example - but does not register where these features are. "Our results showed that it was this face-feature detector that caused the gargoyle-like hallucinations - its indifference to the position of each feature leads to the characteristic distortions of the gargoyle and the overemphasis of face features, the prominent staring eyes."

The recurring association of figure and garden hallucinations seems to relate to how the area of the brain that processes landscapes, gardens and vistas lies next to the one responsible for processing figures and objects. Activity in one is likely to spill over to the other, leading to a spurious association of the two hallucination categories.

The abundance of hats could reflect how cells in the temporal lobe in the brain, which encode elongated shapes, are firing. But ffytche admits that it remains a mystery why the figures should so often be costumed and sporting flamboyant hats, looking like they just walked out of Hogwarts.


------------
© Copyright of Telegraph Group Limited 2006.

Source

And for more wilder fun:

People afflicted with Charles Bonnet Syndrome see beings from another world. Many scientists would call these beings hallucinations. Others call this syndrome a portal to a parallel reality.

http://sprott.physics.wisc.edu/pickover/pc/bonnet.html

 

[Dingo667]

I didn't know where to put this, was wavering between the ghosts thread and human condition.
The reason I wanted to put this in the ghost section is that it could explain a hell of a lot of sightings. It also explains some fairy sightings etc. Whilst this is a hell of a strange affliction, seeing things is explained by a disorder.
I couldn't help thinking though, what if the illness isn't causing the sights but enables the sights?
Especially as it mentions that not all patients have these symptoms?
[Is it me or did we have a similar thread already? If so I am sorry but I think its worth posting anyway, maybe it could be merged].

http://www.dailymail.co.uk/health/artic ... enses.html

Ghostly faces and visions of 'little people': The eye disorder that leaves thousands of Britons fearing they've lost their senses

By Morag Preston
Last updated at 8:06 AM on 03rd February 2009


Following his wife's death six years ago, David Stannard has become accustomed to spending quiet evenings alone at his home in Walton-on-Thames, Surrey.

So it came as a surprise to the 73-year-old when he looked up from his television one evening to discover he was sharing his living room with two RAF pilots and a schoolboy.

'The pilots were standing next to the TV, watching it as if they were in the wings of a theatre,' he says.
Fairy

An estimated 100,000 people in Britain have Charles Bonnet Syndrome (CBS), which leads to hallucinations. These can include visions of miniature people

'The little boy was in a grey, Fifties-style school uniform. He just stood there in the hearth looking puzzled. He was 18 inches high at most.'

Mr Stannard's guests never said a word and vanished after 15 minutes. That night, he says, the walls of his house, which had always been white, looked as though they had been redecorated in patterned wallpaper with a brickwork effect.

The next morning he was caught off-guard again when he found a fair-haired girl standing on his sofa. She also appeared to be from the Fifties, but was life-size, wearing a short skirt and pink cardigan, with chubby knees, white ankle socks and ribbons in her hair.

'I watched her for a while,' he says. 'She didn't move much. Then she was gone.'

It would be easy to dismiss Mr Stannard's story as the bizarre imaginings of an elderly mind. Fortunately, he knew he wasn't losing his mind; neither was his house haunted.

A few weeks earlier he had been registered blind, though he was still able to watch television if he sat at a certain angle. He'd been warned that as his eyesight deteriorated, he might experience visual hallucinations in the form of Charles Bonnet Syndrome (CBS).

'I was lucky enough to know what it was,' he says, 'otherwise I would have thought I was going bonkers.'

An estimated 100,000 people in the UK have CBS, but many won't realise it because the condition remains something of a mystery.
The late historian Lord Dacre of Glanton jokingly referred to his 'phantasmagoria'

Lord Dacre of Glanton jokingly referred to his 'phantasmagoria'

The real number is probably higher because sufferers are often too ashamed to talk about what they have seen for fear of being considered crazy.

The late historian Lord Dacre of Glanton, formerly Hugh Trevor-Roper, was unusual among CBS patients in that he talked openly about what he jokingly referred to as his 'phantasmagoria'.

He would see horses and bicycles racing, and whole landscapes whizzing by as if he were on a train. On one occasion, he found himself trapped in an apparently endless tunnel.

Hallucinations tend to have common themes: simple geometric patterns, disembodied faces with jumbled features, landscapes, groups of people, musical notes, vehicles and miniature figures in Victorian or Edwardian costume. They can be in black and white or colour, moving or still, but they are always silent.

The condition was named after Charles Bonnet, an 18th-century Swiss natural philosopher whose grandfather had seen people, patterns and vehicles that were not really there. Bonnet was the first person to identify that you could have visual hallucinations and still be mentally sound.

The condition can affect anybody at any age with diminishing eyesight. Even people with normal vision can develop it if they blindfold themselves for long enough.

But most people who have CBS have it as a side-effect of age-related macular degeneration - the most common cause of blindness in the UK. It is thought that up to 60 per cent of patients with severe vision loss develop CBS.

Crucially, CBS is caused by lack of visual stimulation rather than mental dysfunction.

Usually, on opening our eyes, the nerve cells in the retina send a constant stream of impulses to the visual parts of the brain. If the retina is damaged, the stream of impulses reduces, but - rather than lie dormant - other parts of the brain become hyperactive.

So when the brain isn't receiving as many pictures as it is used to, it builds its own artificial images instead from the areas we use every day to process faces, objects, landscapes and colours.

What you hallucinate depends on which part of the brain these increases are located. But why only a proportion of patients with macular degeneration experience hallucinations is still unknown, or why younger patients with macular degeneration are less likely to have CBS than older ones.

Dr Dominic ffytche, a senior lecturer at the Institute of Psychiatry, is a leading expert on CBS. He has been at the forefront of a campaign led by the Royal College of Ophthalmologists and The Macular Disease Society calling for eye doctors to warn patients with macular degeneration that they may develop CBS.
It is thought that stimulating the fingertips, for example by feeling a dice with dimples, can help sufferers of CBS stop experiencing hallucinations

It is thought that stimulating the fingertips, for example by feeling a dice with dimples, can help sufferers of CBS stop experiencing hallucinations

He says: 'In our experience, forewarning and knowledge of the possibility of hallucinations helps patients cope when they occur. It allows them to realise this indicates a functional problem with their sight and not a problem with their mind.'

In 2003, Sandra Jones, 54, a former TV producer, thought she was losing her mind when she started seeing faces looming towards her out of nowhere.

Having visited various massacre sites, including Rwanda, as part of her job, she assumed it was a form of post-traumatic stress disorder.

'Part of me thought this was payback time,' she says.

The faces would swirl off the pages of the book she was reading, or appear in front of her computer screen. It would happen three or four times a day, usually when she was feeling relaxed or trying to get to sleep.

'Some nights I couldn't lose them and I would only get an hour's sleep,' she says. 'Closing my eyes wouldn't help, so I'd get up and clean my house just to keep moving. I got the feeling that if I was tired, it would help me fall asleep, which would then free up my mind.'

She didn't dare tell friends or anyone at work for fear of jeopardising her job, and found out about CBS only after researching her symptoms online. Earlier that year she had been diagnosed with Sorsby's fundus dystrophy, a rare genetic eye condition which causes early onset macular degeneration, but nobody had warned her that hallucinations might be a side-effect.
If the retina is damaged, the stream of impulses reduces and other parts of the brain become hyperactive (file photo)

If the retina is damaged, the stream of impulses reduces and other parts of the brain become hyperactive (file photo)

'The unpleasant feeling was of not being in control,' she says. 'Once they are identified, they are not a problem.'

Hallucinations can last from only a few seconds to several hours. In a minority of unlucky cases, they are continuous throughout the day. Patients usually have several daily before they taper off to once a week, then once a month.

For 60 per cent of patients, they will stop entirely after 18 months. There has not yet been a long-term study, but some patients report having them for at least three years.

Part of Dr ffytche's research involves looking into ways patients can stop the hallucinations. 'There won't be a single recipe for everyone,' he says. 'But hallucinations tend to occur when you are in a state of drowsy wakefulness, so you want to rouse yourself.'

As the condition is caused by a lack of stimulation in the visual part of the brain, one of the techniques he is investigating is stimulating the fingertips.

This is based on the fact that studies of brain scans of sight-impaired people reading Braille show increased activity in that area. The theory is that even feeling a dice with dimples could bring visions to a halt.

Other techniques include holding your breath; turning on a light if it is off, or vice-versa; standing up if you are sitting down; and moving your eyes. In extreme cases, medication is used. But the drugs can have side-effects such as tremors, drowsiness, sickness and diarrhoea.

Dr Winfried Amoaku, chairman of the Scientific Committee of the Royal College of Ophthalmologists and a specialist in macular degeneration, says when they come to visit him, patients do two things: first, they request that nobody else is in the room before mentioning the hallucinations, then afterwards they breathe a sigh of relief.

For Mary Orr, 84, from West Kilbride, the final straw was seeing the walls of her house covered in white fur. In desperation, she started to claw at them. 'It was then I thought: "I can't live like this," ' she says.

After months assuming she had dementia, she was referred to a psychiatrist who recognised the signs of CBS straight away and told her to see an eye doctor.

It explains why she still sees pink squares and snakes rising out of the pavement, but Mary is resolute that the worst is behind her. As she says: 'It's the fear of not knowing what's happening that you can't live with.'

• The Macular Disease Society, www.maculardisease.org, 0845 241 2041; Royal National Institute for the Blind, www.rnib.org.uk, 0303 123 9999.

 

[escargot]

Yup, I've read accounts of this interesting condition on here.

One elderly gent endured/enjoyed a vision of a scantily-clad young woman walking through his lounge each evening. :lol:

 

[Dingo667]

Yup, I've read accounts of this interesting condition on here.

One elderly gent endured/enjoyed a vision of a scantily-clad young woman walking through his lounge each evening. :lol:

I bet he didn't complain? Hehe

 

[rjmrjmrjm]

There was a good article on this by Paul Devereux in FT 184, June 2004 (The Lovecraft issue).

Once again, FT beats the mainstream media.

 

[DelphisBorn]

Charles Bonnet Syndrome:

...Of which one of the oft reported hallucinations is of diminutive beings in distinguished dress...eg stovepipe hats, period clothes, etc. Apparently odd beings wearing hats is a very common vision with this condition.

One is reminded of the "fairy funerals" people used to see, with sombre little beings surrounding a tiny coffin.

Interestingly, it is caused by eye disease and vision deterioration, as if the interpretive modules of the brain are struggling to make sense of new blocks of ambiguous data. But why fairies with stovepipe hats etc?

Or does CBS allow access to a well appointed dimension involving great sartorial elegance in small-scale tailoring?

The elderly woman sitting in his office seemed sane enough, but the story she told was decidedly odd. About two and a half years earlier, she said, she'd begun having strange visions. The first time it happened, she was sitting quietly at home when she suddenly saw three or four two-inch-high, stovepipe-hat-wearing chimney sweeps parading in front of her, ladders in hand. "She was thinking, 'Well, I'm going crazy now,' " recalls Teunisse,. "But they didn't harm her, so she thought, 'What the heck, I'll try to catch me one.' But when she went near, they disappeared. So she knew it was some kind of optical trick." Her only medical problem of note was that she had poor sight due to macular degeneration.

 

[QUESTioner]

RE: Charles Bonnet

Wow Delphisborn! I was just about to post on this same thing. Talk about synchronicity!

People afflicted with Charles Bonnet Syndrome see beings from another world. Many scientists would call these beings hallucinations. Others call this syndrome a portal to a parallel reality.

People with Charles Bonnet Syndrome (or "Bonnet-people") are otherwise mentally sound. The beings appear when the Bonnet-people's vision deteriorates as a result of eye diseases such as age-related macular degeneration -- or when patients have had both eyes removed. Charles Bonnet Syndrome is more common in older people with a high level of education.

Bonnet-people report that they see apparitions resembling distorted faces, costumed figures, ghosts, and little people.

Most Bonnet-people see beings wearing hats. For example, one very sane woman was sitting quietly at home when she suddenly saw several two-inch-high, stovepipe-hat-wearing chimney sweeps parading in front of her. (ref 2.) She tried to catch one, but could not. Her only medical problem was that she had poor sight due to macular degeneration.

http://sprott.physics.wisc.edu/Pickover/pc/bonnet.html

Yeah, this really is a strange one I haven't been able to understand, as one has to ask themselves how certain folks essentially could be having the same hallucinations. It defies logic in my opinion.

Haha Elf, we have been down the same road before on this one.

 

[MachineElf]

RE: Charles Bonnet

People afflicted with Charles Bonnet Syndrome see beings from another world. Many scientists would call these beings hallucinations. Others call this syndrome a portal to a parallel reality.

People with Charles Bonnet Syndrome (or "Bonnet-people") are otherwise mentally sound. The beings appear when the Bonnet-people's vision deteriorates as a result of eye diseases such as age-related macular degeneration -- or when patients have had both eyes removed. Charles Bonnet Syndrome is more common in older people with a high level of education.

Bonnet-people report that they see apparitions resembling distorted faces, costumed figures, ghosts, and little people.

Most Bonnet-people see beings wearing hats. For example, one very sane woman was sitting quietly at home when she suddenly saw several two-inch-high, stovepipe-hat-wearing chimney sweeps parading in front of her. (ref 2.) She tried to catch one, but could not. Her only medical problem was that she had poor sight due to macular degeneration.

http://sprott.physics.wisc.edu/Pickover/pc/bonnet.html

Yeah, this really is a strange one I haven't been able to understand, as one has to ask themselves how certain folks essentially could be having the same hallucinations. It defies logic in my opinion.

That is such a fascinating condition, guys

The article says "Perhaps when vision deteriorates, the brain's visual cortex is starved for information, and the brain is free to access parallel realities."

But I cannot help but think that the visual cortex, starved of information, tends to generate it's own stimulation. So, a sufficient explanation for the visuals might lay in the visual cortex stimulating itself. I can't think of a sufficient mundane explanation for the content of the stimulation though.

What if this kind of thing goes on all the time, with a range of content, but it is only the wacky stuff that attracts our attention. Some people may be predisposed to fantastic kinds of visuals just because they have an extraordinarily creative mind. If I were visualizing little people, they would most certainly wear pointy hats and pointy shoes. I know myself. :lol:

 

[eburacum]

A large proportion of sightings of so-called black triangles will be misidentification of mundane lights in the sky ...

Some will be hoax reports, and some will be hallucinations, delusions, or poorly remembered events. Not all hallucinations are caused by disturbed mental states, by the way; I have personal experience of someone who hallucinated a UFO due to Charles Bonnet syndrome, a purely non-psychological phenomenon.

http://en.wikipedia.org/wiki/Charles_Bonnet_syndrome

 

[David Plankton]

I think there was something in a recent FT about an eye condition which caused the sufferer to see 'little people'.

 

[shelleybell]

Possibly Charles Bonnet syndrome? Peeps who have lost some vision can experience it, basically the brain fills in the gaps with hallucinations!

 

[Mythopoeika]

Possibly Charles Bonnet syndrome? Peeps who have lost some vision can experience it, basically the brain fills in the gaps with hallucinations!

Yes. Caused by macular degeneration.

 

[shelleybell]

I dug this out from an old copy of dispensing Optics,

Charles Bonnet was Swiss. He was a lawyer by profession, but he devoted much of his life to studying philosophy and nature. In 1769 he reported that his 89 year old grandfather (whose vision was deteriorating) had begun to experience visual hallucinations. These might take the form of people, buildings and other everyday objects.
Diagnostic criteria for Charles Bonnet Syndrome (CBS) are generally accepted to be:
1 The presence of formed, complex, persistent or repetitive visual hallucinations
2 Full or partial retention of insight into the unreal nature of the hallucinations
3 Absence of hallucinations in other sensory modalities
4 Absence of primary or secondary delusions
In simple terms patients “see” things that are not really there. Many patients are reticent, embarrassed indeed frightened to discuss this phenomenon with clinicians because they fear they are losing their sanity. The hallucinations may take the fairly benign forms reported by Bonnet, but some patients report giant spiders :creepy: and other more alarming objects.

I have only come across this a few times at work, but I think it is a fascinating subject! It would certainly explain a few odd sightings.

 

[EnolaGaia]

This 2021 study determined that CBS patients' visual hallucinations were aggravated by the isolation conditions associated with the COVID pandemic. The full research paper is accessible at the link below.

---

Jones L, Ditzel-Finn L, Potts J, et al.
Exacerbation of visual hallucinations in Charles Bonnet syndrome due to the social implications of COVID-19
BMJ Open Ophthalmology 2021; 6:e000670.
doi: 10.1136/bmjophth-2020-000670

Abstract
Objective Charles Bonnet syndrome (CBS) occurs secondary to sight loss, characterised by spontaneous visual hallucinations. Symptom manifestation can be influenced by social isolation. This research aims to evaluate the effect of the COVID-19 pandemic lockdown on patients with CBS.

Methods and analysis A prospective cross-sectional survey of 45 individuals with active CBS. Open and closed ended questions were used to measure patient-reported features of hallucinatory experiences during the COVID-19 lockdown and perceived episode triggers. Analysis comprised of descriptive statistics, analysis of variance and associations, supplemented with qualitative descriptions. ...

Conclusions Around half of respondents in this survey experienced exacerbation of visual hallucinations during the COVID-19 pandemic, which may partly be explained by loneliness and/or environmental triggers. We provide suggestions to promote effective patient self-management of symptoms. ...

SOURCE / FULL REPORT: https://bmjophth.bmj.com/content/6/1/e000670

 

[EnolaGaia]

This 2007 research report provides a historical overview of hallucination syndromes, including CBS. It illustrates the emergence of CBS and how certain types of hallucinations came to be strongly associated with CBS. The full report is accessible at the link below.

---

Ffytche D. H. (2007).
Visual hallucinatory syndromes: past, present, and future.
Dialogues in clinical neuroscience, 9(2), 173–189.
https://doi.org/10.31887/DCNS.2007.9.2/dffytche

Abstract
In 1936, two clinical rewiews, one by de Morsier, the other by L'Hermitte and de Ajuriaguerra, formulated an approach to visual hallucinations that continues to this day. Breaking with previous traditions, the papers championed visual hallucinations as worthy of study in their own right, de-emphasizing the clinical significance of their visual contents and distancing them from visual illusions. De Morsier described a set of visual hallucinatory syndromes based on the wider neurological and psychiatric context, many of which remain relevant today; however, one - the Charles Bonnet Syndrome - sparked 70 years of controversy over the role of the eye. Here, the history of visual hallucinatory syndromes and the eye dispute is reviewed, together with advances in perceptual neuroscience that question core assumptions of our current approach. From a neurobiological perspective, three syndromes emerge that relate to specific dysfunctions of afferent cholinergic and serotonergic visual circuitry and promise future therapeutic advances.

SOURCE / FULL REPORT: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3181850/