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Retinitis
pigmentosa is a slowly progressive, bilateral degeneration of the
retina and the pigmented epithelium of the choroid. The condition
is of incompletely understood genetic origin. Symptoms include night
blindness and altered visual fields. Diagnosis is by funduscopic findings,
such as dark pigmentation in a bone-spicule configuration in the
equatorial retina, narrowed retinal arteries, a waxy yellow disk, degenerative
vitreous opacities, cataracts, and myopia. Electroretinography aids
in the differential diagnosis. No effective treatment exists.
Abnormal gene coding for retinal proteins appears to be the cause of retinitis pigmentosa. The hereditary pattern is unclear. In most cases it appears to be autosomal recessive but may also be autosomal dominant or, infrequently, X-linked. It may occur as part of a syndrome (eg, Bassen-Kornzweig, Laurence-Moon).
Symptoms,
Signs, and Diagnosis
The retinal rods are affected, producing defective night vision that may become symptomatic in early childhood. A mid-peripheral ring scotoma (detectable by visual field testing) widens gradually, so that central vision eventually is reduced.
The most conspicuous funduscopic finding is dark pigmentation in a bone-spicule configuration in the equatorial retina. The retinal arteries appear narrowed, the macula may develop cystic edema, and the disk may have a waxy yellow appearance. Other manifestations can include degenerative vitreous opacities, cataract, and myopia. Congenital hearing loss may be associated.
Diagnosis may be aided by specialized testing (eg, dark adaptation, electroretinography). Other retinopathies that can simulate retinitis pigmentosa (eg, those associated with syphilis, rubella, and phenothiazine or chloroquine toxicity) must be ruled out. Family members should be examined as necessary to establish the hereditary mode. Families with a history of a hereditary syndrome may wish to seek genetic counseling and may desire testing of family members.
Treatment
No treatment slows the course of the retinal degeneration. Vision loss is typically slow but relentless. Vision drops as the macula becomes increasingly involved and usually evolves to legal blindness.
Last full review/revision November 2005
Content last modified November 2005
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