As you already know the image is projected on a layer of pigment inside the eye, comparable with a film in a camera. On a film, too, there are a number of pigment layers which first need to be developed in the laboratory. The equivalent of the film developing process is taken care of by the retina itself which is on top of the pigment layer, with its millions of tiny, point-form cells for scanning the image. This image sensing naturally takes place in real time. The electrical signals created in the process are collected together in a thick bundle of cables - the optic nerve - and transmitted across the brain, past the pituitary gland and via specially constructed switching centres in the brain making connections, for example, to our sense of balance organs and the cerebellum, arriving finally at the visual cortex - the part of the brain which we use to perceive visual images.
And what happens if degeneration sets in? Degeneration literally means "breakdown". What breaks down and what symptoms are there at the start of this disorder?
Everything has to start somewhere. At the beginning of retina degeneration there are only low level, if any, visual defects. From what we know today it seems that a wafer-thin layer which protects the retina from harmful metabolism breakdown products starts to crack. The result is a lack of vital nutrients and protective substances and oxygen. This deficiency is compensated for by newly formed blood capillaries which destroy the retina, slowly but surely.
Here are a few examples. The dimensions are those of a healthy retina. The macula covers an area of roughly 1.5 mm