Charles Bonnet Syndrome and its associated visual hallucinations were discussed when Newcastle University researcher, Daniel Collerton, took to the stage the AOP’s Hospital and Specialty Optometrists Conference (HSOC) 2024.
HSOC 2024 was held at Emirates Old Trafford, Manchester, on 21 and 22 September.
Collerton, a retired consultant clinical psychologist, began his session by emphasising the difficulty of conveying visual experience in words.
“One of the challenges in working with hallucinations is really understanding what the phenomena is like,” he said.
Collerton’s presentation demonstrated what visual hallucinations can look like, using an illustration described as ‘a kaleidoscope in a shop,’ as well as spiral, swirling and geometric patterns.
The hallucinations associated with Charles Bonnet Syndrome might be more complex, Collerton noted, using an example of a patient who had seen semi-transparent Great War soldiers approaching her from the corner of a room.
Patients experiencing visual hallucinations present with a wide range of different experiences, Collerton shared.
Reported hallucinations have included tigers and panthers in the house, miniature chessboards and wedding rings, distorted faces, old-fashioned costumes, walls covered in purple flowers, and caricatures of pirates and gargoyles.
A child who had had his eyes removed reported seeing ‘scary dogs and Barbies blowing poisoned bubbles.’
The different hallucinations, “illustrate the variety of these experiences,” Collerton said.
He added: “One of their hallmarks is that they are very individual indeed – very much what that particular person sees at that particular time. Even people who hallucinate can have a range of different hallucinations over time.”
He noted, though, that there are some recurring themes, “which are probably just what the brain is specialised to see in the environment: other people, animals, objects, buildings.”
These visions can be distorted to some degree, Collerton said: “You can see faces with big eyes, big noses, big chins. You can see old-fashioned costumes. You can see people with bits missing, and disembodied faces.”
He added that the question of why these hallucinations happen is one that science does not yet have answers for.
One of the challenges in working with hallucinations is really understanding what the phenomena is like
A common experience
Visual hallucinations might be experienced by up to a third of patients attending a hospital low vision clinic, Collerton said.
“Many will never have talked about it, for fear of what the consequences would be,” he told OT.
“These are fairly common experiences, that are often under-recognised and under-reported,” he added. “They cause unnecessary alarm to the people who experienced them. They are not well understood, and they are not easy to get rid of.”
There are ways to make people experiencing visual hallucinations feel better, however.
In his talk, Collerton noted that people will often ask whether they will experience hallucinations forever, and whether there is anything they can do to alleviate this.
There is “uncertainty and anxiety, especially at the beginning,” he said, adding that it is important to reassure patients that they are not alone, and that other people are experiencing the same thing.
The severity of a patient’s eye disease is the most important factor in whether they will experience hallucinations, Collerton said.
“Unfortunately, because we don’t know what causes it, we don’t have effective treatments for getting rid of it,” he added.
Treatments to reduce visual hallucinations have a “poor formal evidence base,” Collerton said.
He also noted that understanding of visual hallucinations increases rapidly when it is explained to patients, and that as a result the impact only remains extremely negative for around one third of people.
After 10 hallucinations, the vast majority of patients (94%) know that what they are seeing is not real, Collerton said.
This leads to most patients eventually feeling “emotionally neutral” about their hallucinations.
However, he advised that one in 20 patients continue to believe that their hallucinations are real, and that these patients should be referred on – although he acknowledged that there is not a clear referral pathway for the condition.
A health psychologist within the hospital or a primary care mental health team are options, Collerton said.
If a patient has co-morbidities, a phone call to explain their hallucinations would also be helpful, he said.
He noted resources including the Macular Society, Esme’s Umbrella, the Royal National Institute of Blind People, Charles Bonnet Syndrome Foundation (Australia), and CBS Visions.
Collerton advised that hallucinations that are not visual are likely to be a sign of wider problems with sensory loss, and that patients should also be referred on in this instance.
He noted that only 5% of patients with visual hallucinations will voluntarily speak about their symptoms, and that only a third of those with Charles Bonnet Syndrome feel well supported.
He advised that the best way to ensure that patients are comfortable speaking about their hallucinations is by practitioners being comfortable speaking about the issues themselves.
“Having some words that you feel quite happy using, and that you can practice and try out with other people, is a good pointer,” Collerton said.
He advised establishing what is already known, before asking about the visual effects that people with eye disease might experience – animals or people, for example – and leaving the question open to allow the patient to elaborate.
Establishing trust and pre-empting patients’ questions, and emphasising that hallucinations are a normal part of sight loss and “not a sign of madness” are important, Collerton said.
Practitioners should also forewarn patients by explaining that the brain will try to fill in gaps if eye disease means it cannot see what is there, and that this is a normal thing.
It is in fact “the brain working really hard to compensate for a problem elsewhere,” Collerton said.
A physical, visual and cognitive health review, as well as person-centred therapy, are also likely to be valuable for these patients.
Collerton added that half of those with an existing eye disease do not relate their hallucinations to their existing condition.
Patients often attribute hallucinations to something else, for example madness, he explained, “which is one of the reasons why people keep these experiences to themselves, and remain unnecessarily distressed, for longer than they ought to.”
“It is comforting for people to learn that there are other people with these experiences, and to learn from them,” Collerton said.
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