by D. Vogt

Created on: March 09, 2010

Retinitis pigmentosa is a serious progressive eye disease which causes increasing loss of vision over the course of a person's life, often leading to legal blindness during late middle or early old age. Unfortunately the condition is genetic rather than acquired, but new research does offer hope for people with this condition. According to the Foundation Fighting Blindness, there are actually several specific types of retinitis pigmentosa, depending on the types of cells which are most seriously afflicted. These include Usher syndrome, Leber's congenital amaurosis, and rod-cone disease.

- Occurrence -

About 100,000 Americans are believed to have RP. As a genetic disease, it is passed on to them at conception, either from one parent or both. The specific cause is known to be a set of genetic mutations in the coded instructions in the DNA for the eye. Depending on the particular set of mutations involved, and the particular form of RP, the trait may be dominant (passed to all children carrying the gene), recessive (passed on only if both parents carry the genes), or on the X chromosome, in which case it affects only boys, because the correct DNA on the second X chromosome in girls is used by the body in place of the mutated copy.

Because RP is a genetic condition, people with RP in their ancestry should consider themselves at greater risk and therefore be evaluated appropriately by an eye doctor for evidence of the condition. However, because RP can be passed on recessively, it is possible to acquire the condition even if no parents or grandparents are affected by it themselves.

- Symptoms -

The different types of RP have somewhat different symptoms, because different cells are affected. The cells used for detecting light on the back of the eye, rod cells (which are most useful for night vision and peripheral vision) and cone cells (which require brighter light conditions, but can detect different colours), are usually the first to suffer. If cones begin to be affected first, people usually notice that they are beginning to have difficulty seeing in distinct colours and focusing on objects in the centre of their vision. If the rods are affected first, then people begin to notice an increasing inability to see at night.

These symptoms usually begin to appear in teenagers and young adults, although there are exceptions. Once the deterioration begins, it will typically continue throughout the rest of a person's natural life. By their 40s or 50s, most people with RP have suffered extremely serious visual degeneration, and are on their way to being diagnosed as legally blind, if they have not been already.

An eye doctor's examination is necessary to confirm the presence of RP. As the disease progresses, he or she may be able to spot changes in the pigment of the retina and various other indications of degeneration in the back of the eye. However, more specific and genetic tests are available to confirm the diagnosis.

- Treatment -

At present, there is no cure for RP. However, several strategies exist to slow its spread, including increased vitamin A. Some advocate retinal transplants, gene therapies, and stem cell research as possible future mechanisms for treating the condition, but none of these are currently known to work or approved for actual treatment. The best option for the present, therefore, is to take whatever steps are possible to reduce the speed at which RP damages the eyes.

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