What causes visual hallucinations with AMD?

The hallucinations experienced by those with age-related macular degeneration (AMD) or other sight loss conditions are known as Charles Bonnet Syndrome (CBS).

Indeed, recent scientific reviews have found that around one in five people with low vision experience the symptoms of CBS.

Yet despite being a common experience in those with AMD, CBS is a symptom that’s rarely talked about. So when people start seeing animals, changes in space or other people around them, they may think it's the first signs of another illness.

This article will help those living with AMD and their loved ones to understand CBS, its symptoms and how they can be managed.

What is Charles Bonnet Syndrome?

Charles Bonnet Syndrome (CBS) is when people with sight loss experience hallucinations as a result of their poor vision. Most commonly experienced by those with sight loss in both eyes, the hallucinations typically worsen or begin as someone’s vision suddenly deteriorates.

Named after the Swiss scientist and philosopher who discovered the condition, it's important to note that, although these hallucinations can be disturbing, they’re not caused by a mental illness. The hallucinations are purely visual and won’t make any sounds or disrupt the senses of touch and smell.

Our charity partner, the Macular Society created an informative video to explain visual hallucinations and Charles Bonnet Syndrome.

What are the symptoms of Charles Bonnet Syndrome?

The defining symptom of Charles Bonnet Syndrome (CBS) is visual hallucinations. This means people see things that don’t actually exist in the environment around them. They can appear for a few seconds or up to several days and can repeat over months and years.

The types of things people with CBS see can range from shapes, patterns and colours to other beings, people or objects. These hallucinations typically fit into two categories:

The latter type of hallucinations tend to be the most disturbing and confusing. However, being aware of the condition and understanding its causes will help people manage any CBS symptoms they experience.

What causes these hallucinations?

CBS hallucinations are caused when the brain tries to fill in the visual gaps created by sight loss. This is because eye conditions often cause disruptions or miscommunications from the retina at the back of the eye along the optic nerve and into the brain (also known as the visual pathway).

While healthy eyes will be able to give the brain the full picture of what’s in front of them, this isn’t possible as vision deteriorates. To compensate, the brain fills in the gaps that are left with incorrect or fantastical images.

This is particularly the case when vision suddenly deteriorates or when an eye condition has caused damage to key parts of the visual pathway. This includes those with AMD who have damage to the macular, an important patch of cells within the retina.

Can the hallucinations be stopped?

For many people, it’s not possible to stop CBS hallucinations completely. However, recent research by Dr Dominic ffytche at King’s College London (sponsored by the Macular Society) found that certain eye movements can help to reduce the impact of hallucinations.

Specifically, eye movements can help to activate the brain and stop particular hallucinations, including patterns and colours.

How to manage your hallucinations

When CBS hallucinations start, they can be very worrying and confusing. Though it may not be possible for everyone to stop the images altogether, it is usually possible to reduce their frequency and severity.

A recent study by Dr ffytche recommended that people experiencing CBS hallucinations should try the following exercise to stop or reduce the images:

If the hallucinations don’t disappear, repeat the exercise again up to five times. If the hallucinations continue after this, then this exercise is unlikely to work. However, trying it again when you experience different hallucinations is recommended.

If the brain isn’t occupied, then it can start to fill in vision gaps with hallucinations. This means many people experience CBS symptoms when they’re sitting in a quiet environment. Turning on the TV, closing the eyes and moving the head or simply getting up and moving can help stop hallucinations in this case.

Certain types of lighting can also make it more likely for people to experience hallucinations. In some cases, dim light can leave more vision gaps for the brain to fill, so keeping rooms well-lit will be key to minimising symptoms. For others, bright light can cause images to appear, so turning the lights off will help.

Once people understand the type of light that causes or increases hallucinations, they can adjust the brightness level to minimise their symptoms.

By understanding what triggers hallucinations, people living with AMD can recognise them and start to feel more comfortable when they appear. People can do this by:

Exercising regularly and safely, getting enough sleep and having a healthy, varied diet are already known to help slow the progression of many eye conditions. This is the case for those experiencing CBS.

For some, stress or tiredness can cause hallucinations to appear more frequently and for longer. Staying as relaxed as possible and maintaining good sleep hygiene will help avoid worsening CBS symptoms.

Some evidence has also suggested that taking supplements like real ginger or Omega 3 alongside a balanced diet can alleviate CBS symptoms. However, it’s important to get advice from your consultant before making any major changes to your lifestyle.

Experiencing hallucinations can be an isolating and confusing experience. Talking about what you’re seeing with a loved one or specialist support group can help you to feel more comfortable and manage your symptoms effectively.

Getting professional advice is also key to managing your CBS or other AMD symptoms effectively. By signing up for the free OcuPlan service, you can get support from eye care professionals whenever you need it. This will help you understand and manage your CBS or AMD, giving you complete peace of mind.