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What Is Charles Bonnet Syndrome (CBS)?

Interviewer: Sometimes when people lose their vision, they start having hallucinations. It's a condition called Charles Bonnet Syndrome. CBS might not be well-known or documented, but it is extremely common and harmless. Lisa Ord is a licensed clinical social worker. She also has a Ph.D. in social work, and is the Patient Support Program Director at the Moran Eye Center.

So, first of all, Lisa, it's fascinating that many people might actually have this condition but don't say anything about it because they're afraid they'll be diagnosed with mental illness or dementia. So tell me more about that part of it first.

Lisa: Well, I think it's really important for people to realize that they're not going crazy. So the big difference between Charles Bonnet Syndrome and say psychosis caused by mental illness or dementia is the level of insight for number one. People realize that what they're seeing isn't really there. It can't be there. If they don't realize that when it is explained to them that this is caused because your brain hates to have a void, it's used to a lot of visual stimulation. And so it's creating this for you, then it's like, "Oh, okay." Whereas somebody with psychosis or dementia, you can't get them off of that idea that it's real.

Interviewer: And when a lot of people that have this condition are in a support group and they hear that their loss of eyesight also might be related to these hallucinations, they sigh a sigh of relief.

Lisa: Yes. Yes, because here they've kept it a secret. They don't want to tell their family. They haven't wanted to tell their healthcare provider for fear that they're going to be carted off and not able to live alone anymore. A lot of our patients live alone and quite independently.

How the Brain Fills the Void of Vision Loss

Interviewer: Yeah. It's fascinating. So if you start losing your vision, your brain wants to see so badly that it just starts. Tell me more about how it's filling that void.

Lisa: Well, it's interesting to me. We don't know a lot about it, but what we do know is that through some fMRI studies it's the same visual pathways that are engaged when somebody is seeing a hallucination from the Charles Bonnet Syndrome as when they're actually seeing the object. But when they're just imagining the object or visualizing the object, it doesn't engage those same pathways. So we do know that it is as if we are seeing that thing that we're seeing, and people see a variety of different kinds of things.

Common Hallucinations

Interviewer: Yeah. Do you have any examples?

Lisa: Yeah. So I have a patient who saw the Grand Canyon opening up in front of her. Rather disconcerting. She knew it wasn't there, but still, it was a little bit unnerving.

Interviewer: Like the ground opening up . . .

Lisa: The ground opening up.

Interviewer: . . . as if it's a Grand Canyon. Wow.

Lisa: Yes. I've had people who saw flowers or patterns. I've had a gentleman who saw a train just passing in front of his eyes. A lot of people actually see other people, and these are not necessarily people they recognize.

Interviewer: Yeah.

Lisa: In fact, most of the time they don't recognize them.

Are CBS Hallucinations Dangerous?

Interviewer: Can those hallucinations be dangerous?

Lisa: No. They're not dangerous at all.

Interviewer: Not even the person that thinks they see the train? I guess that's better than not seeing a train. Of course, they can't . . .

Lisa: I guess it depends on what you do with it, right?

Interviewer: Yeah. If they're losing their vision, then they're not seeing it. Yeah. Right.

Lisa: Right. But there are lots of things you can do to get the visions to go away.

When Does Charles Bonnet Syndrome Typically Start?

Interviewer: So is there a point in vision loss where it starts to happen? Is there a threshold where if it's going to happen, it might start happening at that point?

Lisa: Well, what we see is usually people who have more of a severe vision loss also maybe a field. A visual field defect where they have a blind part of their vision and that's actually where they're going to see the hallucination in that blind spot.

Interviewer: And do some people still see some real things and then that's also the hallucinations are on top of that as well?

Lisa: Yes. Hallucinations can be almost superimposed on top of that as well. Yes.

Interviewer: Like virtual reality in a way.

Lisa: Yes. Exactly.

Who Is Most Likely to Experience Charles Bonnet Syndrome?

Interviewer: Yeah. So is it primarily older people that get the condition, or is it just we tend to think of it in older people because they're more likely to have lost their vision?

Lisa: Exactly. It can happen to anyone who has had vision before. Your brain has to know how to see. It has to be used to that visual stimulus. But as you said, most blinding conditions are happening in older adults or they're age-related conditions. So that's the population that we're more likely to see them in. It can happen in children.

Interviewer: What are some of the specific conditions where it starts happening? So macular . . .

Lisa: Macular degeneration . . .

Interviewer: . . . could be one of them. Yeah.

Lisa: The big one. Glaucoma, diabetic retinopathy. There are many different kinds of conditions that cause blindness. It doesn't really matter. It's not really tied to one condition or another.

Can Charles Bonnet Syndrome Be Cured?

Interviewer: Got you. Is it curable?

Lisa: It is not necessarily curable. There are things you can do to get the hallucination to stop. Sometimes they just stop on their own.

Interviewer: Okay. So just because it happens once doesn't mean it's going to continually happen?

Lisa: Right.

Interviewer: Okay.

Lisa: I have some patients who have it continually quite a bit. Other patients, it's like, "Yeah, that's happened to me once or 

twice."

Managing Charles Bonnet Syndrome: Practical Strategies to Reduce Hallucinations

Interviewer: Okay. All right. And what are some of the strategies for managing it?

Lisa: So one thing that you want to do is change the lighting in your room. So if you are in a dim room, turn on the lights, and open the drapes. Another thing that you can do is blink rapidly, change your location, do something else, something that engages your brain, whether it's a hobby or talking to someone else, giving your brain another kind of stimulation.

How to Talk About Charles Bonnet Syndrome with a Doctor

Interviewer: If somebody believes they or a loved one has Charles Bonnet Syndrome, what should they do at that point? Should they go see an eye doctor? Do you go see somebody else?

Lisa: Well, they can go see an eye doctor. They can see their primary care, but not being afraid to mention that, "I have vision loss and I am also seeing these interesting or not so interesting visions." That doesn't necessarily mean you're crazy. And providers, even though they may have learned about this once in medical school, they don't think to ask people. So if you are a provider that works with older people, remember if they have vision loss, ask, "Do you see things that aren't there?"

Interviewer: Yeah. And frame it.

Lisa: And frame it.

Interviewer: And frame it that this is . . . yeah.

Lisa: We have patients who see things that aren't there and they know that. Is that happening to you?

Supporting a Loved One with Vision Loss and Charles Bonnet Syndrome

Interviewer: What about if you have somebody who has lost vision in your life? Is this a conversation you should have with them, just to make it safe for them to talk about it?

Lisa: Yes. I think just opening up that conversation by saying, "I heard about this the other day, and I was wondering if that's ever happened to you."

Interviewer: Yeah.

Lisa: It's totally normal.

Interviewer: And I bet a conversation like that could take just a load of stress off of somebody that thinks that they're going crazy, right?

Lisa: Huge.

Interviewer: Yeah. What do you think that the ultimate takeaway that you would like somebody to have as a result of the conversation we had about Charles Bonnet Syndrome?

Lisa: I think the ultimate takeaway is that it is not as rare as we once thought. We find that about one in four of our patients with vision loss have experienced this. So talk to somebody about it. You're not going crazy.

 

_{updated: February 11, 2025
originally published: August 15, 2018}