Retinitis pigmentosa (RP) is a group of inherited eye diseases
that often leads to severe visual problems. The retina is a
layer of light-sensitive tissue that lines the back of the eye.
It converts visual images that we see into nerve impulses that
it sends to the brain. Some types of RP are associated with
other inherited conditions. This disorder is named for the
irregular clumps of black pigment that usually occur in the
retina with this disease. |Normal Anatomy of the Eye| |Copyright
© Nucleus Medical Media, Inc.| Many types of RP are caused by a
genetic mutation. Some cases occur sporadically. Vision loss
occurs when light-sensitive cells in the retina gradually break
down. There are two types of cells in the retina: - Cones—These
cells are found mostly in the center of the retina. Cones are
needed for central vision and to see colors. - Rods—Located
mostly away from the center, rods respond to dim light. They
provide night and peripheral vision. In most forms of retinitis
pigmentosa, the rods die. Visi