Retinitis pigmentosa (RP) is a term used for a group of disorders that are characterized by inherited, progressive dysfunction, cell loss, and eventual atrophy of retinal tissue. Initial involvement of photoreceptor leads to subsequent damage to inner retinal cells. Eventually, there is widespread atrophy of several, if not most, layers of the retina.
The initial visual impairment is night blindness and visual field loss. The age of onset varies in the different types of RP, from infancy to adulthood. The disorder is a dystrophic and not inflammatory. The progressive loss of peripheral visual field in patients with RP is insidious and occurs first in the superior visual field. Central visual function can be seriously affected early, while significant peripheral field remains. Cystoid macular edema can also occur early in the disease and can respond to treatment.
Usher’s Syndrome is an autosomal recessive congenital deafness with retinopathy indistinguishable from typical RP.
Diseases confused with RP include Rubella retinopathy, syphilis, infectious retinitis such as toxoplasmosis or herpes, cancer-associated retinopathy, melanoma-associated retinopathy, drug toxicity (Thioridazinen, Chlorpromazine, Chloroquine, Quinine), pigmented paravenous retinochoroidal atrophy, traumatic retinopathy, diffuse unilateral subacute neuroretinitis, and grouped pigmentation of the retina (bear tracks).
RP is incurable, but treatable. Large amounts of vitamin A are recommended. Careful refraction, cataract extraction when indicated, treatment of macular edema, and referral for low vision aids is recommended. Clinical research trials with fetal tissue transplants, growth factors and photomicrochips are underway. Visual field testing should be done on a regular basis, with electroretinogram being done one for progression monitoring.
Limiting light exposure has yet to be proven in humans, but glasses with UV protection cannot hurt the eye. Future experiments manipulating genes involved in retinal apoptosis may prove successful.