Mr Nicholas Glover  - Consultant Cataract Surgeon
Charles Bonnet Syndrome

Some people with sight loss experience visual hallucinations because of the problems with their eyesight, this is known as Charles Bonnet Syndrome

Many worry unnecessarily that there is something wrong with their mind. Hallucinations can occur because of sight loss, particularly through macular degeneration. It is important to understand these hallucinations are a natural experience and not a sign of any mental illness. 

When hallucinations happen as a result of sight loss they are known as Charles Bonnet Syndrome after an 18th century Swiss scientist and philosopher who first described the condition.Up to half of all people with macular degeneration are thought to experience Charles Bonnet Syndrome hallucinations, sometimes referred to as CBS. 

Visual hallucinations are more likely to occur if both eyes are affected by sight loss. The hallucinations often start after a decline in vision.

What do these hallucinations look like

Charles Bonnet hallucinations can be simple unformed flashes of light, colours or shapes. However, many people see more elaborate forms such as geometrical grids and lattices. Some people report seeing disembodied faces with staring eyes, landscaped gardens or vistas, animals, people, or processions of miniature costumed figures wearing hats.Ironically, the hallucinations are often seen in more vivid detail than real life.

Can you stop the hallucinations

Using eye movements to lessen the impact and length of hallucinations. Eye movements activate visual parts of the brain in people with macular disease – even if they have little remaining vision. These movements may stop certain types of hallucinations, particularly the grids, checkerboards, lattices and colours.

Try these exercises to help make the hallucinations disappear: 

 • Imagine two points about a metre (3ft) apart on a wall in front of you. Stand about a metre and a half away and look from one point to the other once every second or faster for 15–30 seconds followed by a break of a few seconds. Hold your 5 Macular Society eyes open during these movements. 

• Shutting your eyes or looking away. 

 • Switching on the room lights. 

• Sometimes simply getting up and doing something else can cause hallucinations to disappear, however they often continue unaffected.