Charles Bonnet Syndrome: Busting Myths and Understanding Visual Hallucinations

In this episode, we are joined by Dr Jasleen Jolly, who talks about Charles Bonnet Syndrome. Charles Bonnet Syndrome (CBS) is a condition where people with sight loss experience visual hallucinations.  In this talk, Dr Jasleen Jolly talks about the latest research into CBS and busts some CBS myths before answering listeners' questions.  Dr Jolly is an Associate Professor in Multidisciplinary Vision research at Jolly Vision Science LTD, based in the UK. During the talk, Dr Jolly mentions several resources and a questionnaire-based study into CBS.  A link to all these resources are below.

• Esme's Umbrella - https://www.charlesbonnetsyndrome.uk/
• Charles Bonnet Study - https://tinyurl.com/sight-impairment-study
• Aspectum | A Short Documentary - https://www.youtube.com/watch?v=s6CdM6XwX2I
  
  

Chapters

• 0:00 Intro
• 1:15 Busting Myths About CBS
• 9:52 Understanding the Causes of CBS
• 13:54 Exploring Treatment Options
• 17:15 Ongoing Research and Studies
• 18:20 Audience Questions and Experiences
• 28:38 Outro

Transcript

[0:00] Rainbow Group. Live well with sight loss.

[0:07] Hello and welcome to the Live Well with Sight Loss podcast for June 2025. A series of talks to educate, inspire and entertain. In this episode, we are joined by Dr. Jasleen Jolly, who talks about Charles Bonnet Syndrome. Charles Bonnet syndrome is a condition where people with sight loss experience visual hallucinations. In this talk, Dr. Jolly talks about the latest research into CBS and busts some myths surrounding Charles Bonnet syndrome before answering listeners' questions. Dr. Jolly is an Associate Professor in Multidisciplinary Vision Research at Jolly Vision Science Ltd. based in the UK. During the talk, Dr. Jolly mentioned several resources and a questionnaire-based study into CBS. A link to all these resources are in the show notes.

[1:07] Music.

[1:16] Thank you very much, Tim. Please forgive my voice. I'm just recovering from a chest infection, so just bear with me. So I'm going to talk to you today about all of our research on Charles Bonnet syndrome and we have been doing an awful lot over the last few years, so that's why I wanted to update you all.

[1:38] Some of you may have participated in some of this. So the key questions around Charles Bonnet syndrome were what is the prevalence well I still can't give you an answer on that because the prevalence studies are quite difficult to do and need to be done very systematically and it's quite difficult to get everybody in the clinic that comes through to answer those questionnaires and unless you get everybody to answer those questionnaires, you can't get true prevalence. Then what is the mechanism behind Charles Bonnet syndrome? And I can give you some details on that. And then what is the treatment? So, but before I go into that, I want to bust some myths. Myth number one, Charles Bonnet only occurs in the elderly.

[2:30] Well, no, it doesn't. So a research group in London found that CBS also occurs in children so it can occur at absolutely any age so we can bust that myth it can occur absolutely at any age the only prerequisites that you need for CBS is a that you've had some vision before and b that there's some level of loss in it and actually on the Esme's Umbrella so i i hope you've all heard of Esme's Umbrella, it's the one charity dedicated to Charles Bonnet syndrome. And on the Esme's Umbrella website, there's now a whole page dedicated to pediatric loss. There was some funding for Lee Jones and his group.

[3:23] They had some funding and they designed, with patient participation, They designed a CBS monster called M, and this is resources dedicated to talking about CBS to children. So you can check that out on our Esme'sUmbrella's page. CBS, myth number two, CBS has a low prevalence. Well, no. I mean, some of the prevalence work that I've done is showing as high as 60% of patients can experience CBS at some point during their visual loss journey. Now, the difficulty with CBS is we don't know when it occurs during the vision loss journey. It can occur at the beginning, middle, or later on. We need to do more work on that but it can be as high as 60% we don't really know but estimates vary anything from 20 to 60 percent of people experience some type of CBS at some point and i've just realized i've not actually defined what charles bonnet is which is a poor start but I blame my infection for my adult head.

[4:40] So Charles Bonnett Syndrome is the occurrence of secondary hallucinations as a result of visual loss. So the brain's used to getting all this visual information, and what's suddenly happening is because it's not getting that information, it's kind of making stuff up. So you've probably all heard of phantom limb syndrome. when you lose a limb, you get sensations of that limb still being there. This is the visual equivalent of that. And we actually published a paper where we compared phantom limb syndrome, the neuroscience behind phantom limb syndrome, Charles Bonnet syndrome, and the hearing equivalent, which is tinnitus. Because there are actual similarities between the three syndromes. They all occur after you've got sensory loss of input into the brain, and there are actual similarities in the underlying neuroscience, as well as the treatment of them.

[5:42] So it only occurs when you've got loss of vision, some sort of visual impairment. And it doesn't matter what kind of visual impairment. It can be absolutely anything, anything from Macular Degeneration to brain injury, anywhere along the visual pathway. It can occur any time of life, as I've already said. But the difference is that the hallucinations that you experience, you have insight into the fact that they are not real. So you can be logicked into knowing that they're not real because the hallucinations are clear, your vision is not. So that's the key difference between some kind of psychosis and other mechanisms that cause hallucination. So you know it's not another form of mental health disease that is causing hallucination like Schizophrenia because in Schizophrenia you absolutely believe the hallucinations are real no matter how much someone persuades you otherwise and that's a key diagnostic criteria.

[6:53] So if you if you have insight into the fact that they are not real and you've got visual impairment, then it's Charles Bonnet syndrome. Okay, so we've busted the myth of the fact that CBS has a low prevalence. Myth number three, CBS only occurs with significant visual loss. So that was previously put out that you need to have, I can't remember the exact number, I think it was something like 60% vision loss. Well, actually, we recently published that even if you have vision loss in one eye, you can still have CVS and the other eye is completely normal. So we busted that myth. You only need to have some form of vision loss. The exception is cataract because cataract happens so slowly that the brain has time to adapt.

[7:46] Any other form of vision loss it doesn't matter so we've even reported that with temporary forms of vision loss so things like a retinal detachment which happens for a short period because then it's fixed by surgical repair it can cause vision loss so that happens again in one eye and then there's some the hallucinations resolve after you've got the surgical repair and the vision's back to normal. And then the hallucinations go away.

[8:19] So you don't need to have a high degree of vision loss. It can occur with any degree of vision loss. The key thing is that your vision drops and that causes a disruption into the visual signal into the brain. So because the hallucinations are clear, your vision is not, we know that this is coming from the brain. And that's important when i talk about the mechanism a bit later on okay so myth number three CBS only occurs for a short time so it used to be thought that CBS occurs for a maximum of three years and then it sorts itself out not so i've got patients that they've had the hallucinations for 14 years or more and they're still ongoing with no sign of resolution so in some people the hallucination can last for a few weeks, a few months, in other people a few years, in other people many years. We don't know why that is. It's incredibly variable between people. Some people have scary hallucinations, some people have very pleasant hallucinations that they learn to enjoy. And again, no idea why that is. So.

[9:36] And if you have scary hallucinations, obviously we need to deal with those. If people have pleasant hallucinations, great, enjoy them.

[9:46] There's nothing wrong with that. And if you have neutral hallucinations, then that's fine. I'll talk about management strategies at the end. So what causes CBS? So we did a number of neuroscience studies around this. So first of all, we looked at MRI in people who had hallucinations and people who didn't have hallucinations to compare their brains. And we looked at a number of different factors of their brain. Unfortunately, because of the pandemic, we struggled to recruit enough numbers. We didn't find there were any major differences in the brains of people with hallucinations and low vision and people without the hallucinations and low vision.

[10:27] Reassuring. I mean, that may have been because we didn't get enough numbers. But it also may have been because actually the brain signals are different so we looked at a number of factors we looked at what happens to the response when you look at objects and we looked at the pathways of how what break the at rest what signaling patterns are happening and we also looked at the neurotransmitters but there's only limited neurotransmitters we have the strength to look at with MRI. So it may not have been quite the right ones that we were looking at. So another study we did, so that was a study I did with my colleagues in Oxford.

[11:11] I now live in Cambridge, though not for much longer, and I did a study where we took people who have frequent hallucinations, and we looked at the signal, what happens to the brain waves just before hallucination during a hallucination and at the end of a hallucination and this is where it gets really interesting because we actually found a different a change in the brain wave pattern at the start of a hallucination and then that that change disappeared at the end of the hallucination so there's there's a change in the brain at at the start of the hallucination and And the way we know that is we got people to press a button at the start of each hallucination. And because these are people who hallucinate frequently, they had multiple hallucinations during our one hour recording session. And we were able to verify it wasn't related to the press of the button because otherwise you'd expect to see that signal change at the beginning and at the end of the hallucination.

[12:23] So it's not a motor response, but it is related to the actual hallucination. So, yeah, so there's clearly something going on related to the hallucination. And that change in signal was happening specifically in the visual area, which is at the back of the head in the brain. So we've now found a signal in the brain related to Charles Bonnet syndrome. So now we have that. The next step is to go out and educate all the medical professionals. Because unfortunately, one of the reasons why diagnosis rate is quite poor is that understanding amongst professionals is still quite low.

[13:10] And actually this afternoon, I'm doing a presentation to vision scientists and doctors worldwide through an organization, the Association of Research in Vision and Ophthalmology, where we'll be trying to raise that education rate and deciding how are the next steps? What's the next way to raise the awareness and not just in ophthalmology but amongst other professions such as GPs and other relevant medical professions and allied health professions as well so that's the kind of the next step we need to go to.

[13:54] So potential treatments, drugs have shown a really poor efficacy they just don't work with CBS because they're not targeting the right pathways so the limited information that has been out there showing drugs they just don't work, actually the most effective way is knowledge because quite often people don't talk about their CBS because they're afraid of being pegged as being crazy so actually what one of the things I'm on a crusade for is to get everybody screened, to get people actively asking the question about it in the clinics. Because if we can start openly talking about it, then people can get reassured. Patients can get reassured that this is actually expected. They're not going crazy and it's fine and and that way the symptoms are not going to control them you can control the symptoms.

[15:04] So knowledge is the number one effective method. Secondly, counselling. Because the images actually are from your experience. You're never going to hallucinate images that are completely alien to you. So, for example, someone who's Christian is never going to hallucinate a Buddha.

[15:28] Or someone who's never heard of Buddha is not going to hallucinate Buddha. So in different cultures, you're going to get different hallucinations. So if you're a fan of horror, you're more likely to hallucinate horror, things like that. So yeah, that's why counseling can be helpful. Some people, there are case reports that frequent blinking can help, but they are case reports. They're not, there's been no big scale studies on that. Some people report closing eyes and resting can help. Some people report ignoring the hallucinations can help. Some people report interacting with their hallucinations can help. And recently, there was some work, there was a study where trans cranial electrical stimulation helps. So this came from a Parkinson's trial because the Parkinson's hallucinations are very similar to CBS. Yes. And so because the hallucinations are in the brain, what they did is they applied a current directly to the visual area over the brain. And they found that that was able to suppress the hallucinations. So that could be a potential treatment for those who find the hallucinations particularly troublesome or distressing. But as I said before if you find the hallucinations pleasant just interact with them or enjoy them if you find the hallucinations pleasant.

[16:56] Not that bothersome, just ignore them. So I think the only ones who really need to focus on treatment are the ones that find them really distressing or scary or so frequent that they're interfering with day-to-day life. Ongoing studies.

[17:11] So there is one study that is ongoing at the moment.

[17:16] I'm just going to put a link in the chat. It's a questionnaire-based study that you can just do online in your own time tim and susie if you wouldn't mind spreading that amongst all your membership that i would be really grateful so if people could answer whether you've got hallucinations or not so we're looking for participants both with low vision who have hallucinations and low vision who don't have hallucinations to answer and we're trying to look for we're trying to predict who will get the hallucination using that questionnaire so anyone with low vision basically we would appreciate if you could answer the questionnaire that would that would be great thank you so that's the only ongoing study I've got at the moment in CBS but the best place to look out for anything that's ongoing is the Esme's Umbrella website.

[18:14] Anything to do with CBS tends to be listed on there.

[18:19] Great. And I will stop there and take any questions that anyone has. It's Tim from Sight Advice. Yeah, I think you might have half answered this one's been baffling me on Charles Bonnett. I mean, situational hallucination, for example, I'll give you two examples. One simple and one extreme, but they're true ones. somebody who.

[18:44] Would be in their house, they'd look to their left, and they'd see geometric shapes on the left side of the room, look to the right, and they wouldn't. Okay, fine. And that would be consistent every morning.

[18:57] And another one, though, which is much more strange, somebody who, in Morecambe Bay, which is a big bay area in the northwest, stretching from Morecambe all the way to Barrow, when he was looking into the sea in Morecambe Bay, no matter where, Morecambe, Range Over Sands, Barrow, didn't matter where and he was an ex-building contractor as well so this is how your path answered already but he'd say a full working of a building site trains and everything when he went to Blackpool 10 miles down the road and looked out there all in St. Ann's nothing I mean it's yeah I can't we don't know we don't know why you see certain images at certain how it like the brain is a funny thing it's such an interesting organ your vision is not just made up of what you what you see actually one of the reasons our vision is so fast is it's created off of feed forward which is the input from your eyes and feed fast mechanisms So one of the theories behind Charles Bonnet syndrome is this imbalance between feedforward and feedback input.

[20:19] So feedback is memory, which modifies the input coming in, and that makes your vision much quicker. Nice so if you've got less visual input coming in the memory overrides that so it may be large open space building site overtakes because of his job, whereas in blackpool because it's more built up already there's no space for a building site. Right. Yeah, it's just a strange one. Anywhere in Morecambe Bay, he would see this. Yeah. Because it's an open space, so the brains association is, oh, there must be a building site here. Right. Okay. Anybody else got any questions? It's Antony from Sight Airedale. I was just wondering, is there any link between the sort of hallucinations people get? in Migraine to Charles Bonnett.

[21:31] In migraine, that's an interesting question because we've actually been having a debate on that within the professional community. So again, another theory behind CBS has been related to blood flow in the brain. And that's also a theory in migraine. So one of the things that i so i've been taught in talks with someone in the states about doing a study with them in their clinics and potentially looking at the the co-prevalence of migraine and CBS to probe that exact mechanism because both of those are related to like if if there is a higher prevalence of both, like in the same people of both migraine and CBS, then that would point to the fact that both groups would have changes in the blood supply in the brain.

[22:38] But we don't know. I've got a question. Can you hear me? Yes. Yes. Yeah. Everything you've said, I agree with from my experience because I notice all kinds of almost like kaleidoscopic visions when I first started losing my eyesight, but it seemed to settle down. But the only time I've noticed it since is when I've had to go into hospital for.

[23:07] Angioplasty, which is a bit of a stressful procedure. And in the days that followed, I had visions of my sisters. Now, whether that's a pleasurable experience or a scary experience is another thing but I think it's possibly due to the the nitrates they give you for the operation to dilate your blood vessels so stress stress also increases CBS um so um it was reported so studies were done during the pandemic and both stress and isolation were shown to increase hallucinations hmm.

[23:49] But that's the only time I've noticed it. And it lasted a few days, and it was in my peripheral vision, so it wasn't central to the side. But the thing that was remarkable was these images were very detailed. They're more detailed than I can see with my eyes. So obviously it's something going on inside the brain. And it would last probably half an hour, and you could switch it off by distracting yourself. Let's just find something else to occupy your mind and they tend to go away but i can put all this in your your survey if you like yes absolutely that would be great thank you tim again one thing which i've a myth i bought into by the way which obviously i won't go into anymore it's a bit about the timing i've definitely have been on sort of uh zooms where not from yourself I'm Charles Bonnet where we've been told it has been like it is a temporary sort of thing I actually put that information out to people and they tell me it's more of a comfort thing sometimes but to say it's fine you'll not people know it's not a real hallucination as you mentioned but it is temporary so how.

[25:05] Is that something new or is that something, it's just been a myth? It's been a myth. It's been a myth that's been around for a long time that's just been perpetuated and perpetuated. I'm working with a wonderful artist at the moment. I just need to get some funding for her. And then we're hoping to hit up some science festivals. And she's created some interactive art based on her hallucinations, which we're hoping to display and she um she's had hallucinations for 14 years oh wow and they are showing no signs of abating and i've had multiple other patients who similarly have had hallucinations for decades and um esme's umbrella have a wonderful video out and both of the, let me see if I can find the link, both of their participants in that movie have had their hallucinations for decades, and again show no signs of abating. Is the sort of, is that a rarity? No, no. Or is it a sort of, you know, is there any like rough percentage? Because some people do obviously. No, there's no sort of 50% are going to lose it.

[26:26] We don't know. Right, okay. Thank you. Okay, I'll keep more neutral on that one then. Okay, thank you. Yeah, as I said before, the prevalence studies are really difficult to do. Yes. I've put the link to the documentary video in the chat. It's really well worth watching. Nice. Thank you. Thank you.

[26:54] Could I ask a question? Yes. My name's Lyndon. I don't get hallucinations during the day, as the CBS seems to be, but during the night time, sometimes when I close my eyes and relax, I get very clear visual pictures at night when I'm relaxed. It seems to be the opposite way around. No, that's really common. Is it? It's really common for people to get them as the light going down. At dusk yeah that's really common in fact during the EEG study we simulated those light conditions for quite a few of the participants we dimmed light in the in the room to simulate those conditions in order to elicit the hallucinations oh right now it's when i actually close my eyes though is this yeah so i used to think you couldn't get hallucinations when you closed your eyes And during the course of the EEG study, I was completely devolved with that myth. Right. Thank you very much. So, yeah, I found out that's more common than I realised.

[28:06] So I was taught at university, you only got the hallucinations with eyes open. But, yeah, it's not true. grand, thank you. Have we got any more questions? I am going to let Dr. Jasleen go, where her voice goes. Have we got any more questions? Thank you so much. I'll get better soon. Thank you. This has made me much better than I was.

[28:32] Music.

[28:39] We do hope you enjoyed this episode. If you'd like to join us for our live recording of our podcast, you can do so via Zoom. Talks take place on the second Thursday of the month at 10am London time. The Zoom ID is 458043 7872. That's 458-043-7872 Live Well is a series of talks aimed at helping people make the most of life with sight loss. Live Well is a collaborative project between six local independent sight societies. Sight Advice South Lakes, Cumbria My Sight Nott's, Nottingham Sight Airedale, the Airedale area of North and West Yorkshire Support for Sight, Mid and West Essex Sutton Vision, the London Borough of Sutton And Outlookers, Huddersfield, West Yorkshire.