WHAT IS RETINITIS PIGMENTOSA?

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What is Retinitis Pigmentosa: Retinitis Pigmentosa (RP) is the name given to a group of degenerative diseases of the retina of the eye. The retina lies at the back of the eye and it acts like the film in a camera, receiving and processing everything you see. The retina is a delicate layer of cells which picks up the pictures and transmits them to the brain. In humans there are two types of light sensitive cells within the retina: rod-like cells and cone-like cells.
What are rods and cones?: Rod cells pick up movement out of the corner of the eye and also, in a normal eye, it Is the rods that operate in poor light or at night. There are as many as 120 million rods in each eye and they are more numerous towards the outer edge of the retina. The cone cells are used in color vision and in close precision work like reading. There are not so many cones and they are more numerous in the centre of the retina.
What causes RP?: RP may be caused by a breakdown in the function of the rods or the cones in some other part of the retina. The retina is so complex that breakdown may occur in one of a variety of ways and so RP is not a single disorder but a great number of disorders. In fact some ophthalmologists (eye specialists) may call the breakdown of cone function macular degeneration. Other disorders similar to RP have names like gyrate atrophy, choroideremia etc. The common feature is a degeneration of the retina for one reason or another. Research provides opportunities for the scientists to look for particular causes of retinal disorders.
What are the symptoms of RP?: It depends what form of RP you have but one early symptom is difficulty seeing at night or in poor illumination. Others report problems with ball games. With loss of rod function there is a narrowing of the field of view so that gradually, as the degeneration progresses, it seems as if you are looking down a tunnel -- a tunnel which can narrow as the years go by. This is why RP is sometimes called "tunnel vision." If there is a break-down in the cone function then the picture you see becomes fuzzy and it becomes harder to read and to recognize faces.
Is there a treatment to arrest the degeneration process?: As you can see from the answers above, the causes of retinal degeneration are numerous; this makes it unlikely that a single treatment will emerge that will stem the progress of all forms of retinal breakdown. Many ideas have been tried out to retard retinal degeneration but none has stood the test of time. However, scientists are now looking for suitable treatments and many possibilities are being investigated.
Does retinal degeneration lead to blindness?: To the layman blindness is complete loss of vision. Some people with retinal degeneration become blind in this sense, but most retain limited residual vision; though they may be termed as blind for legal purposes, or "legally blind."
How quickly does sight diminish?: Each person is different and each must be assessed by an eye doctor. The progress of retinal degeneration is individual although if the disorder runs in the family then the rate of progression may be similar within that family. Most people have a gradual degeneration. So in most cases there is a chance to adjust to the visual handicap.
Can retinal degeneration be easily diagnosed?: This depends on the type and extent of the deterioration. Frequently, a characteristic change in the appearance of the retina is visible to the ophthalmologist. A proper eye examination is needed to determine the precise state of the retina.
Is only vision affected?: Yes, in the great majority of cases. However, for a few there are other disorders as well as the retinal degeneration. One example is Usher's Syndrome in which deafness accompanies RP. There are a number of other syndromes, too.
Can an eye transplant be performed?: The retina is connected to the brain by a complicated network of nerve cells. With present scientific knowledge it is most unlikely that transplants will be an answer to retinal degeneration disorders. You may hear of eye transplants being performed but these refer to corneal transplants which bear no relation to RP.
Is retinal degeneration inherited?: In most cases the answer is yes. The most common form of inheritance is called recessive. This means that both parents carry the gene which causes RP. They themselves are unaffected but on average one in four of their children will have RP. Another form of RP inheritance is sex-linked. In sex-linked RP females carry the gene causing RP, and when a female carrier marries a normal male there is a 50% chance that their sons will be affected and a 50% chance that their daughters will be carriers. Sex-linked RP is the one form for which carriers can often be detected. In sex-linked RP when an affected male marries a normal female all their sons are unaffected and all their daughters will be carriers. There is also a dominant form of RP which can strike in every generation of a family. Since RP runs in families all members in an affected family are urged to have a proper eye examination and when planning a family you may wish to seek expert genetic counselling.

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