What is Retinitis Pigmentosa (RP)?
Retinitis Pigmentosa, or RP for short, is the name given to a group of degenerative eye diseases affecting nearly 1 in 3,000 Australians. ‘Retinitis’ is meant to indicate a disease of the retina and ‘Pigmentosa’ refers to a discolouration of the retina often associated with it. The retina normally acts like, the film in a camera. It is a layer of light sensitive cells ill the back of the eye which picks tip the picture and transmits it to the brain where ’seeing’ actually occurs. Unfortunately, in RP the retina degenerates, causing vision to progressively diminish.
What are the symptoms of RP?
One of the earliest symptoms of RP is ‘night blindness’ where there is difficulty seeing at night and in dimly lit places. This is accompanied by a progressive loss of peripheral vision (side, tipper and lower), leading to ‘tunnel vision’. Frequently, in time, central vision also deteriorates. Blindness is common. RP is the leading cause of youth blindness in Australia and is second only to diabetes as a cause of blindness in the working-age population.
What causes RP?
It is the death of photoreceptor cells ill the retina which is responsible for the symptoms of RP. This is caused by a defective gene which fails to have the essential balance of proteins produced to keep photo receptor cells healthy. So far research scientists have discovered over 30 defective genes causing forms of RP.
Is RP inherited?
Retinitis Pigmentosa is inherited through any one of three main genetic pathways. Firstly, the recessive type of RP is the most common. It can strike in families with no history of blindness and can affect either sex. About 1 person in 80 carries a recessive RP gene but transmission of RP to a child requires that both parents carry the gene. A child then has a 1 in 4 chance of inheriting RP.
Secondly, dominant RP usually appears in every generation of an affected family. Its transmission to a child requires only one parent to carry the defective gene so that there is a 1 in 2 chance of having an affected child with each birth. Thirdly, X-linked RP is transmitted by a female carrier to a male child. There is a 1 in 2 chance of a male child inheriting RP and a 1 in 2 chance of a female child being a carrier.
Does night blindness mean a person has RP?
No, in some cases night blindness does not represent any significant eye disease.
How quickly does vision diminish?
Every person affected by RP needs to be individually evaluated by a specialist eye physician because the progression of RP can vary considerably from person to person. Vision impairment can be gross in early childhood in some cases, whereas in others there can be more gradual impairment of vision with the progression of symptoms over time.
Is only vision affected?
Yes, in most cases. However, a minority is affected by syndromes combining RP and one or more other problems. One example is Usher syndrome, in which deafness from birth accompanies RP.
Is there a treatment to arrest the progression of RP?
Means of effectively treating and preventing RP are not yet available. However, world-wide scientific research is bringing them rapidly closer. In the foreseeable future gene therapy may make it possible to substitute a healthy gene in the retina for a defective one, the process of premature retinal cell destruction may be controlled, and the transplantation of retinal cells may become routine.
Who to contact?
Retina Australia (SA) Inc:
* promotes research into the causes, treatment and prevention of RP;
* assists people affected by RP and their families and friends;
* provides information about RP and increases public awareness of it;
* raises funds for these purposes.
*Source: Retina Australia (SA) Inc
