Retinitis pigmentosa

Retinitis pigmentosa (RP) is a group of inherited dystrophies of the retina. It's a chronic and progressive degenerative disease which causes progressive loss of retinal photoreceptors, causing progressive vision loss ending in blindness. It usually begins in childhood or early adulthood. There is no known cure. The prevalence is 1 per 5000, and 50% of cases are familial.

Etiology

Mutations in many genes can cause RP, and there are multiple patterns of inheritance, including autosomal dominant, autosomal recessive, and X-linked. The rhodopsin gene, which codes for the rhodopsin protein, a light-absorbing protein in the photoreceptor cells, is perhaps the most commonly affected gene. Approximately 50% of cases are familial.

Pathology

Despite the name, there is no inflammation involved. The gene mutation causes progressive degeneration of the photoreceptors.

Clinical features

The most common symptoms are night blindness, peripheral visual field loss, and loss of visual acuity. The symptoms progressively worsen, usually insidiously, so that the affected person doesn't notice the visual changes until they start bumping into others or get into accidents.

Diagnosis and evaluation

Fundoscopy shows pigmentary changes (dark spots) in the retina (which gives the pigmentosa part of the name), a pale optic disc, and arterial attenuation. Full-field electroretinogram, Goldmann perimetry, and dark adaptometry may also be used to aid the diagnosis.

Treatment

There is no known cure for retinitis pigmentosa. Experimental gene therapy is being developed which may slow progression in some forms of RP.

Prognosis

The vision loss is progressive, but in some cases the affected person isn't legally blind before death. However, most patients are legally blind by the age of 40.