Retinitis Pigmentosa

The term retinitis pigmentosa (RP) refers to a group of hereditary diseases, all of which eventually result in severe vision loss. Some of the diseases in the RP family are Usher syndrome, Lebers congenital amaurosis, rod-cone disease, Bardet-Biedl syndrome, and Refsum disease. Approximately 100,000 people in the U.S. have RP.  Symptoms usually surface during adolescence or young adulthood, although some RP diseases are apparent even in infants. RP progresses at different rates in individuals, but most people with RP are legally blind by age 40. Some forms of retinitis pigmentosa are associated with other disabilities, such as deafness in people with Usher syndrome.  

Scientists have restored vision in mice with retinal degeneration by transplanting stem cells at a specific stage in their development. Restoring vision in humans with RP and macular degeneration through a similar process is still years away, according to the researchers, but human clinical trials have already started.

Findings by researchers working with the grant support of Research to Prevent Blindness (RPB) lead to the discovery that RP symptoms are caused by the death of cells in the retina. The retina is a light detecting layer inside the eye that sends visual images to the brain. In most cases of RP, retinal cells called rod photoreceptors are the first to die, followed by cone photoreceptors. Rods are concentrated in the periphery of the retina. They help us see in dim light. Therefore, as the death of rod cells advances, night vision and then peripheral vision progressively disappear. In fact, night blindness is an early symptom of RP.  When cones die first, central vision and color vision are impacted before peripheral vision.

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