Hallucinations – a common (but surprising!) side effect of vision loss

On 16th November, people from across the UK came together to mark Charles Bonnet Syndrome (CBS) Awareness Day and shine a spotlight on the condition, which is a relatively common symptom of vision loss, but one that’s rarely talked about.  

Up to 50% of people with severe vision loss experience CBS, which causes them to see things that aren’t really there. The hallucinations can take lots of different forms – from random flashes of light, to geometrical shapes and shadows. Some people even see parades of people or animals, or stunning landscapes! There’s often no rhyme or reason to CBS – hallucinations can be in full colour or black and white, last for seconds or hours, and be static or moving. After the initial shock has worn off, some people learn to enjoy their hallucinations and find them entertaining, but for others, they can be scary and disturbing.  

People are more likely to experience CBS if both their eyes are affected by vision loss, but it can occur in people who only have sight loss in one eye. The hallucinations often start after a sudden or rapid deterioration in the quality of someone’s vision. CBS has been reported in people with a variety of eye conditions, but it is more prevalent in people with age-related macular degeneration (AMD) or advanced cataracts. 

It can be disconcerting – and often frightening – to experience hallucinations for the first time. They can be hard to distinguish from reality – like a random animal sitting on the end of your bed, or a brick wall in the middle of the road – although some people have reported seeing mythical creatures like dragons and unicorns too!  

You can read more about some of the hallucinations people with CBS commonly experience on the RNIB website.  

People often worry that their hallucinations are symptomatic of a mental health condition, or – because CBS primarily affects elderly people – wonder if they’re developing dementia. That’s rarely the case, though, so if you’ve been diagnosed with AMD or advanced cataracts and you’ve started seeing some weird and wonderful things, or objects in unusual places – try not to worry too much, because you’re not alone, and there are ways to manage your hallucinations. They tend to lessen over time, too, so just because you’re experiencing hallucinations now doesn’t mean you’ll have them forever. 

What causes Charles Bonnet Syndrome? 

CBS is caused by your brain trying to adjust to significant sight loss. When you lose your sight, your brain doesn’t receive as much visual stimuli as it used to, so it can sometimes try to “fill in the gaps” with pictures and patterns that manifest as hallucinations. CBS is usually triggered by a deterioration in your vision and then improves over time as your brain gradually starts to adapt to the change in your vision.  

Is there a cure? 

Unfortunately, there isn’t currently a cure for CBS, but research is ongoing and there are lots of ways to manage your symptoms in the meantime, which we’ve summarised below: 

Remind yourself that your hallucinations aren’t real 

CBS only affects what you see and doesn’t impact on any of your other senses – so if you think you’re hallucinating, it’s helpful to reach out to touch what you’re seeing to confirm whether it’s real or not. If you can’t touch, hear, taste or smell anything related to what you’re seeing, it’s likely to be a visual hallucination.  

It’s also helpful to remember that hallucinations caused by CBS are often very vivid and detailed, so if your vision is usually poor and you’re suddenly able to see something with remarkable clarity, chances are, you’re experiencing a hallucination. 

Some people have recurring hallucinations, so they’re able to familiarise themselves with what to expect and their hallucinations become much easier to deal with over time, so images that initially frightened them don’t faze them anymore.   

Change your environment 

If you’re in a dark room when your hallucinations start, try switching the lights on (or vice versa). Many people find that bright lights help to make their hallucinations disappear. If you’re sitting down, you may want to try standing up and moving around to see if that helps to get rid of your hallucination. 

Find a distraction 

Many people find that their hallucinations start when they’re sitting quietly without much to do. Putting the TV or radio on or finding something to occupy yourself with can sometimes make the hallucination disappear. 

Move your eyes from side to side 

The Macular Society has been working with Dr Dominic Ffytche at King’s College in London to research ways to prevent Charles Bonnet hallucinations.  

Dr Ffytche recommends moving your eyes from left to right without moving your head – you may want to look back and forth at fixed points on a wall to help with this. If the technique isn’t working after several attempts, it’s unlikely to be effective, but it’s worth trying each time you experience a new hallucination.   

Try shutting your eyes/blinking 

You can also try blinking rapidly, or shutting your eyes for a little while. When you open them again, you may find that the hallucination has disappeared. 

Relaxation or mindfulness

Some people find that their CBS hallucinations are worse when they’re tired or anxious, so it’s important to get a good night’s sleep and take some time to relax.  

Support and resources 

Although CBS isn’t caused by a mental health issue, it can still affect your mental health by making you feel fearful or anxious. Some people are also reluctant to tells others about their hallucinations because they’re worried it might sound like they’re “going mad.” If your hallucinations are upsetting you, it’s important to talk about how you’re feeling – whether that’s with your family and friends, or with your GP. If you need help coming to terms or coping with your hallucinations, your GP will be able to refer you to a specialist counsellor who can teach you techniques to limit the impact they have on your day-to-day life.  

You can find more information and advice about CBS on the following websites: 

The Royal National Institute of Blind People 

The Macular Society 

The NHS