Post date: 
Tuesday, 31 October 2017

Charles Bonnet syndrome is common among people who have sight loss, but low awareness of the condition means those affected aren’t getting the support they need. Sam Heaton, who has been newly diagnosed, explains.

The vast majority of the population will never have heard of Charles Bonnet syndrome (CBS). Put simply, CBS is a visual hallucination. It is entirely visual – no sounds are heard to coincide with what’s being seen. It’s not linked to any mental disorder. It happens as the brain tries to make sense of the surrounding environment by filling in the gaps caused by extreme sight loss. Hallucinations vary from seeing patterns and colours, to animals, people or landscapes.

When not seeing clearly is the reality, whilst what you do see clearly is not reality - this is the paradox faced in a life with Charles Bonnet syndrome.

The condition, for which there is currently no cure or treatment, takes its name from the 18th century Swiss naturalist, Charles Bonnet. Bonnet’s first documented case, in 1760, was his 89-year-old grandfather, who was almost blind from cataracts and reported “seeing” a myriad of hallucinations such as people, birds or carriages. Despite this early discovery, CBS was not formally acknowledged by British psychiatrists until 1982.
Though the condition has very little public awareness, it’s incredibly common in people with visual impairments and is frequently associated with many well-known eye conditions. Around half of people with macular degeneration experience some symptoms of CBS, according to the Macular Society, while a study led by researcher R Nesher (2011) found evidence of CBS in 12.9 per cent of people who were defined as having “low vision” as a result of glaucoma. An Australian study (led by O’Hare, 2015) found that more than one in three participants with retinitis pigmentosa, the leading cause of sight loss in the working age population, were affected by Charles Bonnet syndrome.
Despite this high prevalence among the sight loss community, awareness of CBS is patchy among health and social care professionals. The charity Esme’s Umbrella was established in 2015, by Judith Potts (whose mother experienced CBS for many years) as a way of increasing awareness in wider society and providing support to those with the condition. Without this knowledge, “most people suffer in silence because they are afraid of a mental health diagnosis,” wrote Judith in The Telegraph (September 2015). And for those who do open up about their hallucinations, some have been misdiagnosed, most commonly with dementia.
Esme’s Umbrella has led to the condition being publicised in the national press and on national television, but there is still a long way to go before CBS is commonly known and recognised by professionals. Ophthalmologists should also highlight the possibility of CBS to their patients, so that they are already aware of the condition are less likely to experience fear should the symptoms start.. Only then will all who have Charles Bonnet syndrome be able to deal with it openly and be able to access the right support.

Further information

What's it like to experience Charles Bonnet syndrome

Bee has glaucoma. She first experienced CBS when she was shopping. She explains the types of hallucinations she gets and how she copes.

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