What Is Retinitis Pigmentosa (RP)? Retinitis Pigmentosa (RP) is
the name given to a group of hereditary retinal diseases
characterized by progressive loss of visual field, night
blindness and reduced or absent electroretinogram (ERG test)
recording, which indicates that a large portion of the retina is
damaged. RP causes the degeneration of photoreceptor cells in
the retina. Photoreceptor cells capture and process light
helping us to see. As these cells degenerate and die, patients
experience progressive vision loss. There are two types of
photoreceptor cells: rod cells and cone cells. Rod cells are
concentrated along the outer perimeter of the retina. Rod cells
help us to see images that come into our peripheral or side
vision. They also help us to see in dark and dimly lit
environments. Cone cells are concentrated in the macula, the
center of the retina, and allow us to see fine visual detail in
the center of our vision. Cone cells also allow us to perceive
color. Together, rods and cones are the cells resp