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Retinitis pigmentosa (RP) is a group of rare hereditary disorders whose common feature is a gradual deterioration of the light sensitive cells of the retina. The name retinitis pigmentosa was applied by a doctor Donders in 1857. With hindsight it is not a good name; if discovered now, the condition would probably have been named "retinal dystrophies".
Incidence
The symptoms of this group of disorders usually become apparent between the ages of 10 and 30, although some changes may become apparent in childhood. In one type of RP, Leber's Amaurosis, children may become blind - or almost so - within the first six months of life. By contrast, some types of RP may only show symptoms late in life.
Signs & Symptoms
In the more common types of RP, a person will have a history of visual problems at dusk or in poor light, so-called night blindness and a gradual reduction in the field of vision, loss of the outer edges, resulting in a tendency to trip over things.
The first reaction for many is to go for an eye test believing that they need glasses. Although glasses do a marvellous job correcting problems with the eye's lens, they cannot help a deteriorating retina. As the outer fringes of the field of vision gradually disappear, the RP sufferer is left with the condition commonly referred to as tunnel vision. Many people retain this tunnel of useful vision until quite late in life. The speed of loss of vision varies considerably from person to person, due to the many forms of RP.
As these cells slowly degenerate, people with RP develop night blindness and a gradual loss of peripheral vision. By about age 40, most have tunnel vision, although many may retain good central vision. Between the ages of 50 and 80, however, they typically lose their remaining sight. The extent of vision loss in people of the same age with RP may be different.
In one category of RP, the loss of vision begins in the central area. This is referred to as macular dystrophy (because the central macular area is affected). It causes an inability to read or carry out other work involving detail, although the person may have few mobility problems for several years.
Diagnosis & Tests
In some cases RP is first diagnosed following a road accident.
Treatment & Prevention
There is no treatment for retinitis pigmentosa, although some practitioners believe that vitamin A may slightly delay vision loss. Occupational therapy may be wise before much of vision is lost. It may be easier to learn how to work around vision loss while vision is still available.
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Signs, symptoms & indicators of Retinitis Pigmentosa:
Conditions that suggest Retinitis Pigmentosa: | | | | | Organ Health |  Night Blindness | Retinitis pigmentosa results in visual rods being destroyed early in the course of disease, resulting in night blindness. Night blindness in children may be an early indicator of retinitis pigmentosa. |
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Retinitis Pigmentosa suggests the following may be present:
Retinitis Pigmentosa can lead to: | | | | | Organ Health |  Night Blindness| | Retinitis pigmentosa results in visual rods being destroyed early in the course of disease, resulting in night blindness. Night blindness in children may be an early indicator of retinitis pigmentosa. |
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Recommendations and treatments for Retinitis Pigmentosa: | | | | | Vitamins |  Vitamin A| | Some practitioners believe that vitamin A may slightly delay vision loss. According to a study reported in the Archives of Ophthalmology on June 14, 1993, most adults with blinding retinitis pigmentosa should take a daily 15,000 IU vitamin A supplement, based on results from this large, randomized clinical trial.
Eliot L. Berson, MD, the study's principal investigator and Professor of Ophthalmology at Harvard Medical School, said that adults who supplemented their diets with 15,000 IU of vitamin A daily had on average about a 20% slower annual decline of remaining retinal function than those not taking this dose.
Based on this finding, Dr. Berson and his colleagues estimated that an average patient in the study who started taking a 15,000 IU vitamin A capsule at age 32 would retain some useful vision until age 70, whereas a patient not on this dose would lose useful vision by age 63. |
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KEY | | Weak or unproven link |  | | Strong or generally accepted link | | | Proven definite or direct link | | | May do some good |
GLOSSARY
IU (mIU, uIU)
International Unit: An arbitrarily defined but agreed upon unit that depends on what is being measured.
mIU: 0.001 or one thousandth of an IU.
uIU: 0.000001 or one millionth of an IU.
Retina (Retinal)
A 10-layered, frail nervous tissue membrane of the eye, parallel with the optic nerve. It receives images of outer objects and carries sight signals through the optic nerve to the brain.
Thyroid (Thyroid Gland)
The thyroid gland is an organ with many veins, anchored around the front of the throat near the voice box. It is essential to normal body growth in infancy and childhood. It absorbs iodine from the diet and releases thyroid hormones - iodine-containing compounds that help govern the rate of the body's metabolism (its total life processes), affecting body temperature, and regulating protein, fat and carbohydrate catabolism in all cells. They keep up growth hormone release, skeletal maturation, and heart rate, force, and output. They promote central nervous system growth, stimulate the making of many enzymes, and are necessary for muscle tone and vigor. To a high degree, metabolism is regulated by the hormone thyroxine, which can be made by the thyroid if enough organic iodine is available. An enlarged thyroid gland that is not cancer is sometimes called goitre.
Thyroiditis (Chronic Thyroiditis, Hashimoto's Thyroiditis)
Inflammation of the thyroid; there are several forms of thyroiditis, including chronic or Hashimoto's thyroiditis (also called autoimmune or chronic lymphocyctic thyroiditis), subacute thyroiditis, and painless or postpartum thyroiditis. Thyroiditis often results in hypothyroidism.
Vitamin A
A fat-soluble vitamin essential to one's health. Plays an important part in the growth and repair of body tissue, protects epithelial tissue, helps maintain the skin and is necessary for night vision. It is also necessary for normal growth and formation of bones and teeth. For Vitamin A only, 1mg translates to 833 IU.
Last updated: Apr 13, 2008
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