Fig. 1.

RP is a group of genetic progressive diseases, with an estimated prevalence of 1 in 4000 in the United States, that leads to total blindness. Though RP can be caused by mutations in any of over 190 genes, all lead to degeneration of the photoreceptor layer of the retina. The relative preservation of inner retina has led to efforts to develop retinal prostheses to stimulate residual surviving tissue. Left: the classic clinical triad of RP is arteriolar attenuation, retinal pigmentary changes (could be either hypopigmentation and/or hyperpigmentation in form of bone-spicule and pigment clumpings), and waxy disc pallor. Middle cartoon: normal eye. Right cartoon: eye with RP