Retinitis Pigmentosa (RP) Is the Name Given to a Group of Inherited Eye Diseases That Affect

Retinitis pigmentosa (RP) is the name given to a group of inherited eye diseases that affect the retina. Retinitis pigmentosa causes the degeneration of photoreceptor cells in the retina. Photoreceptor cells capture and process light helping us to see. As these cells degenerate and die, patients experience progressive vision loss.

What causes Retinitis Pigmentosa?
It is a genetic disorder. It is programmed into your cells, not caused by injury, infection or any other external agent. Genetic defects (mutations) send faulty messages to the retinal cells which leads to their progressive degeneration, which in turn, leads to vision loss.

Symptoms of RP

Symptoms depend on whether rods or cones are initially involved. In most forms rods are affected first. Because rods are concentrated in the outer portions of the retina and are triggered by dim light, their degeneration affects peripheral and night vision. When the more centrally located cones — responsible for color and sharp central vision — become involved, the loss is in color perception and central vision. Night blindness is one of the earliest and most frequent symptoms of RP. People with mainly cone degeneration, however, first experience decreased central vision and ability to discriminate color.

Functional Implications:

RP is typically diagnosed in adolescents and young adults. It is a progressive disorder. The rate of progression and degree of visual loss varies from person to person. Most people with RP are legally blind by age 40, with a central visual field of less than 20 degrees in diameter. It is a genetic disorder and, therefore, is almost always inherited.An estimated 100,000 people in the U.S. have RP, mainly caused by mutated genes inherited from one or both parents.

Treatment:

Although not a treatment for RP, it is also important to know that low vision aids are useful for maintaining independence. A daily dose of 15,000 I.U. of Vitamin A can moderately slow the progression of RP. There are also several areas of research that offer tremendous promise for halting the disease or restoring vision loss: Retinal Cell Transplantation; Gene Therapy ; Nutritional Therapy;

Pharmaceutical Therapy.

References:

1.  http://www.blindness.org/faq.asp?type=3#3

2.  Cassin, B. & Rubin, M.L., MD, (2006). Dictionary of Eye Terminology Fifth Edition. Page 229. Gainesville, FL: Triad Publishing Co.

3.  http://www.allaboutvision.com/conditions/retinapigment.htm

4.  http://www.blindness.org/content.asp?id=45

5.  http://www.umm.edu/ency/article/001029.htm

A shrinking field of vision is one of the early warning signs of retinitis pigmentosa.

Created by Trish Duke

Region 4 Summer 2008