Seeing things that aren't there: Charles Bonnet syndrome after vision loss

Vivid patterns, faces, even whole scenes — appearing to someone who knows they aren't real. It has a name, it's caused by sight loss rather than mental illness, and knowing that is most of the battle.

What Charles Bonnet syndrome is

Charles Bonnet syndrome (CBS) is the experience of visual hallucinations in people who have lost a significant amount of sight — from eye disease, or from brain-based vision loss like hemianopia after a stroke. The images can be simple (grids, shimmering patterns, colours) or startlingly elaborate (faces, figures, animals, whole scenes). Crucially, the person usually knows, or quickly realises, that what they're seeing isn't real.

Why it happens

When the visual system stops receiving its usual input, the visual parts of the brain can become spontaneously active and generate images of their own — brain imaging during hallucinations shows exactly this (ffytche and colleagues, 1998). It is sometimes compared to phantom limb sensation: the brain filling silence with its own signal. It is not a sign of mental illness, and it is not dementia.

How common is it?

More common than almost anyone thinks. Estimates vary widely — commonly cited figures run from around one in ten to a third of people with significant sight loss (Menon and colleagues, 2003) — and the true figure is probably higher, because many people never mention it for fear of what it might mean. If this is you: you are in large company, and telling your GP or eye clinic will not get you labelled as anything other than someone with sight loss.

What helps

The single most effective thing is knowing what it is — hallucinations that are understood lose most of their power to frighten. Beyond that, people report that episodes can be interrupted by changing the lighting (brighter or different), blinking or moving the eyes deliberately (looking rapidly left–right for a few seconds), changing activity, or standing up. Tiredness and stress tend to make episodes more frequent, so gentle pacing of the day helps here too. There is no routinely used medication for CBS itself; management is understanding, practical tricks, and time — for many people episodes fade over months.

When to seek help — and when quickly

Always mention new hallucinations to your GP or eye specialist so they can confirm CBS and rule out other causes; that confirmation is itself reassuring. Seek advice promptly if the hallucinations involve other senses (voices, sounds, smells), if you're not sure whether what you see is real, if they're distressing or threatening, or if they come with confusion — those patterns point away from CBS and deserve proper assessment.

Common questions

Am I "going mad"?

No. CBS is a recognised consequence of sight loss, produced by a healthy brain responding to reduced visual input. Insight — knowing the images aren't real — is the defining feature.

Will it go away?

For many people episodes become less frequent and less vivid over months to a couple of years, especially once understood. For some they persist longer; support exists either way.

Where can I find support?

In the UK, Esme's Umbrella is a charity dedicated to CBS awareness and support, and the RNIB has patient information. Your eye clinic or stroke team can also point you to local support.

This guide is general information, not medical advice, and does not diagnose or treat any condition. Always follow the guidance of your own care team. Stroke Sight and ReWrite are wellness support tools, not medical devices.