Retinitis Pigmentosa is a progressive disease which attacks the retina, the light sensitive portion of the eye.
The retina is a curved film attached to the inside back surface of the eye, which acts in a similar manner to the light sensitive film inside a camera.
Light, which enters the eye through the lens at the front, is focussed onto the retina which consists of several layers, one of which contains about 120 million tiny bristle-like protrusions called photo-receptor cells.
Their function is to receive the light that is focussed onto them by the lens and, by a chemical process inside each cell, turn it into electrical impulses, which pass along the optic nerve to the brain to make up a picture.
It is a failure of these photo-receptor cells in the retina which causes the condition known as Retinitis Pigmentosa. These cells develop a fault and die or fail to reproduce themselves as they should, due to some fault in the body chemistry.
The research effort supported by B R P S, is directed at finding out what goes wrong with these photo-receptor cells (sometimes referred to as rods and cones), or the chemicals which feed them.
When the mechanism of failure is fully understood or it is known what chemicals are lacking, the battle will be almost won, then it should be possible to devise a means of rectifying the problem.
The symptoms and effects of RP and its associated retinal dystrophies can vary. For some, the visual loss will be slow, with only a slight deterioration of sight over many years. Others have periods of more rapid loss, sometimes with years in between of no apparent decline.
Many experience problems in poor light conditions as the first symptoms. In some cases peripheral sight is lost with the retention of some central vision for many years, whilst in some conditions the central vision is lost first.
Some sufferers, mercifully a small percentage, have multiple disabilities, such as with Usher Syndrome, where RP is accompanied by hearing loss and Bardet Biedl syndrome where several functions are affected.
With so many variations in the symptoms and effects, it is not surprising that the public find RP a difficult disability to understand.
If the restricted central vision is intact, it is possible for those with RP to read or pick out objects in the distance, yet not be able to cross the road safely. It is difficult to appreciate that he or she is severely handicapped and may be on the way to total blindness.
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