RP may be caused by a breakdown in the function of the rods or the cones in some part of the retina. The retina is so complex that breakdowns may occur in a variety of ways and so RP is not a single disorder but a great number of disorders. The breakdown of cone function may be called Macular Degeneration.

There are other disorders similar to RP like Gyrate Atrophy, Choroideremia etc. The common feature is the degeneration of the retina for one reason or another. Researchers are trying to find particular causes of retinal disorders.