Retinitis Pigmentosa

Retinitis Pigmentosa (RP) is a group of diseases that affect the very delicate and thin tissue that makes up the retina. (Read more about retina problems in "The Eye") The retina sends images to the brain. (Read about "The Brain") It does this by using two types of cells. They are called rods and cones. Both types of cells can be affected by RP. In most patients with the disease, the rod cells deteriorate, according to Prevent Blindness America (PBA). Peripheral and night vision depend on the rods. One of the first signs of the disease is a loss of night vision. As the disease progresses, RP patients often have what is called tunnel vision. In other words, they can only see straight ahead, and not out to the side. In severe cases of RP, the eye's cone cells are also affected. These cells help us with central vision and color, according to PBA. About 400-thousand Americans have RP or related disorders, according to PBA. While the disease is mostly thought to be inherited, Retina International (RI) says there are cases in which there is no previous family history. (Read about "Family Health History")

Genetics

RP can be passed on to family members in three different ways. According to The Foundation Fighting Blindness (FFB) they are:

• autosomal dominant - when a child inherits a defective gene from only one parent. That parent typically suffers eye problems. Each child has a 1 in 2 chance of acquiring the disease. There are no carriers.
• autosomal recessive - Where both parents have a defective gene but do not have eye problems. Each child has 1 in 4 chance of acquiring the disease and a 1 in 2 chance of being a carrier. Carriers do not suffer any effects of the disease.
• x-linked recessive - In this case the father, if affected, would not pass on the defective gene to his sons, but his daughters would carry the defective gene. If it is the mother carrying the gene, 1 in 2 sons will be affected and 1 in 2 daughters will be carriers.

FFB says different members of the same family may experience symptoms in varying degrees. FFB recommends that if one family member is diagnosed with the disease, all members of that family contact a medical eye doctor called an ophthalmologist. (Read about "Eye Exams")

Symptoms

Signs of RP usually show up during childhood and adolescence, according to the American Optometric Association (AOA). AOA says that the first sign is usually loss of night vision followed by a loss of peripheral vision. As the disease progresses, the deterioration of peripheral vision worsens. People with RP may bump into objects, as they can only see straight ahead, according to AOA. Most cases of RP take a long time to develop and it could take years for loss of vision to be severe.

RP is considered one of the most common inherited causes of blindness in adults between the ages of 20 and 60, according to RI.

Diagnosis

People who suspect they may have RP should see an ophthalmologist, according to RI. The ophthalmologist can perform several different vision tests including an electroretinogram to determine the condition of the retina, according to RI. While early detection of the disease can be helpful in planning treatment, RI says the disease is most difficult to diagnose in its earliest stages. FFB says that in some cases of the inherited form of RP, a blood test may help reveal whether an affected family member has one of several RP genes.

Related disorders

RP is not alone on the list of inherited retinal degenerative diseases. Some conditions share not only a problem with vision, but other symptoms as well. Usher syndrome (Read about "Usher Syndrome"), for example, causes a loss of vision and hearing. (Read about "Hearing Loss") According to FFB, there are several rare syndromes that researchers are studying. They include:

• Bardet-Biedl Syndrome also known as Laurence-Moon Syndrome
• Best Disease
• choroideremia
• gyrate-atrophy
• Leber Congenital Amaurosis
• Stargardt Disease

Treatment

While researchers are currently working to better understand and treat RP and other inherited retinal degenerative diseases, there is no known cure of this group of disorders. Researchers however have found that vitamin A (Read about "Vitamins & Minerals") and lutein may slow the rate of deterioration, according to AOA. PBA says there are also many new low vision aids that can help people maximize their vision. These include:

• magnifying lenses
• electronic magnifiers
• night vision scopes
• telescopic lenses

Experts advise seeking help from a doctor with experience in low vision rehabilitation.

Related Information:

    Glaucoma

    Cataracts

    Macular Degeneration

    Glossary of Vision Terms