Mind Hacks points out this mindblowing item in the Journal of Clinical Neuroscience: "A Roman chariot, the rider dressed in gold, flashed across the curtain several times. On the ward, tropical vines grew from the foot of her bed. A man stood with thick brown tree trunks for legs and thick green branches for arms. Nurses’ heads would shrink and then expand before melting into the floor. Brightly coloured fairies carrying wands invited her for walks around the hospital grounds."
Charles Bonnet Syndrome sufferers can experience complex colour patterns, images of 'little' people animals, plants or trees and inanimate objects that blend into the person's surroundings.Given the astounding 17% prevalence of these illusions, I wonder if there may be corresponding phenomenon in other modalities, brushings by of ghosts on the arm, or vivid personal perceptions of phantom time, meter and pitch. While the cause is not yet known and there is no treatment beyond reassurance, the good news is the effect generally fades away after a few years.
the basic official theory explaining the visions associated with visual impairment like macular degeneration is that the brain, on receiving incomplete visual data through the eyes, 'fills in' the missing elements as best it can -- a kind of 'best fit' process. In fact, there is evidence that it is only the input of a constant visual stream through our eyes that prevents the brain making up its own imagery in any case.
[ Eye Spirits: Fortean Times UK ]