Retinitis pigmentosa is a group of hereditary disorders whose common feature is a gradual deterioration of the light-sensitive cells of the retina. Postmortem examination of the eyes reveals pigment cells that have clumped together as a result of the pigment epithelium budding off and settling within the layers of the retina. Retinitis pigmentosa often accompanies other hereditary disorders in several distinct syndromes — including Usher’s syndrome, in which sight and hearing are both affected; and Laurence-Moon-Biedl syndrome (most common), which is typified by visual destruction from retinitis pigmentosa, with obesity, mental retardation, polydactyly, hypogenitalism, and spastic paraplegia.
Retinitis pigmentosa can be classified according to its inheritance pattern: autosomal dominant, autosomal recessive, and X-linked. Typically, in all forms of retinitis pigmentosa, the retinal rods slowly deteriorate. Clumps of pigment resembling bone corpuscles aggregate in the peripheral region of the retina and later involve the macular and peripheral areas. Visual symptoms usually appear between ages 10 and 30, though some children may become blind within the first year of life.
Retinitis pigmentosa affects 1 of every 4,000 people in the United States.
Generally, night blindness occurs while the patient is in his teens. As the disease progresses, his visual field gradually constricts, causing tunnel or “gun-barrel” vision. Many people retain this tunnel of useful vision until quite late in life. The speed of vision loss varies considerably from person to person. However, blindness follows invasion of the macular region.
A detailed family history may imply predisposition to retinitis pigmentosa. In the patient whose history suggests this condition, the following tests help confirm diagnosis.
❑ Electroretinography shows a slower than normal or absent retinal response time.
❑ Fluorescein angiography visualizes white dots (areas of dyspigmentation) in the epithelium.
❑ Ophthalmoscopy may initially show normal fundi but later shows black pigmentary disturbance and white dots (dyspigmentation) in the epithelium.
❑ Visual field testing (using a tangent screen) detects ring scotomata.
No cure exists for retinitis pigmentosa. However, vitamin A and E supplementation may slow degeneration. Researchers are working on a procedure in which fetal retinal tissue is transplanted into people with retinitis pigmentosa, but its potential efficacy is unknown.
❑ Teach the patient and his family about retinitis pigmentosa.
❑ Encourage the patient to use sunglasses to protect the retina from ultraviolet light and to help preserve vision.
❑ Explain that the disorder is hereditary, and suggest genetic counseling for adults who risk transmitting it to their children.
❑ Encourage annual eye examinations to monitor the progress of the disease.
❑ Warn the patient that he might not be able to drive a car safely at night.
❑ Refer the patient to a social service agency or to the National Retinitis Pigmentosa Foundation for information and for counseling to prepare him for eventual blindness.
❑ Because the prospect of blindness is frightening, your emotional support and guidance are indispensable.
Review other book chapters online related to Retinitis Pigmentosa:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
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