Faling eyesight to blame for ghostly visits

Ghosts and other hallucinations may be caused by the brain trying to make sense of dwindling signals from diseased or failing eyes.

Studies that have monitored patients' minds found that even people who have had both eyes removed "see" ghostly visions of distorted faces.

Others with a range of eye diseases report seeing knights in armour, people in Edwardian costumes or First World War uniforms, and apparitions wearing hats or helmets.

The best explanation for such visions is that the sufferers' brains are trying to make sense of the falling amount of information arriving from the optic nerve, Dr Dominic Ffytche of the Institute of Psychiatry told the British Association.

"Sixty per cent of people with degenerative [eye] diseases like age-related macular degeneration and retinitis pigmentosa report having these hallucinations," he said. "Some also report seeing serene landscapes or vortices."

By putting the patients into an MRI scanner, Dr Ffytche was able to monitor which parts of the brain became active when the patients reported having hallucinations.

"With some of the people who are badly affected, they can have two or three events in a five-minute period," he said.

"We believe it's caused when no information comes into the brain; it's essentially idle and so it fires on anything and generates images that it tries to interpret."

The patients often reported seeing horribly distorted faces, but the images were not of people they knew, which could begin to explain why reports of ghosts were often from elderly people.

But even people with perfect eyesight could experience seeing apparitions, Dr Ffytche said. "

"If you've ever been to a rave, flashing lights at a particular frequency will cause them. It's just something about the brain."