A rare genetic condition affecting about one in every 4,000 people, retinitis pigmentosa (RP) results in a deterioration of the retinal pigment epithelium. As these cells “die”, they frequently group together forming “spindles”. This is the more common and typical presentation of RP, although there are others. When this occurs there is generally a loss of the peripheral visual field in all quadrants, as the photo pigments that are destroyed lie in the rod cells that are distributed throughout the retinal periphery, as well as in the center to some degree. As the condition progresses there is a resultant “night blindness” or inability to see in the dark or dimly lit environments, as the rod cells are more functional and sensitive in dim illumination, and when they are lost so is the ability to see in the dark. As these cells die the peripheral field is lost leaving only a small “tunnel” of vision centrally.
Retinitis Pigmentosa patients can frequently benefit from lenses that expand the peripheral fields, such as reverse telescopes or amorphic telescopes, and by some of the electronic scopes that amplify light in dim environments to enhance brightness and permit function of the central cone cells in these situations.