Retinitis pigmentosa (RP) consists of a large group of disorders resulting from a progressive loss of the rods and cones in the retina. These are the cells that respond to light and send signals to the brain that enable us to see. Hundreds of mutant genes have been identified as responsible for these hereditary disorders and there is considerable variation in onset and progression of symptoms. The disease usually is present as an isolated eye disease but syndromal forms also occur in which there is a similar disease of the retina in association with other problems elsewhere in the body.
The first symptoms consist of difficulty seeing at night followed by constriction of side vision and these typically appear in young adults but they can be detectable in the first decade of life. About this time fine vision is lost as well and some patients are legally blind by the 6th decade. Eye examinations usually show clumps of black pigment in the retina while the optic nerve that connects the retina to the brain shows damage as well.
A considerable number of individuals with RP have no family history of this disease. However, the family pattern in many cases is consistent with autosomal dominant inheritance in which the mutations are passed from parent to child. Affected parents can expect on average that half their children will inherit the same disease.
In retinitis pigmentosa 47 there is both autosomal recessive and autosomal dominant inheritance.
The disease is usually diagnosed by an ophthalmologist based on the symptoms and the appearance of the retina. An electrical test called an ERG is often used to confirm the diagnosis. There are no signs of disease outside of the eye in most cases. Lifespan is not impacted.
Low vision aids and mobility training can be great benefit. High doses of vitamin A palmitate have been shown to slow the progress of the disease but this requires careful monitoring to avoid complications of liver damage. Several new therapies are under investigation but these are not yet clinically useful.
Individuals with retinitis pigmentosa have an increased risk of developing cataracts. Cataract surgery is indicated in patients when the lens opacities interfere with vision.