Improperly called "Pigmentary retinitis", it is a serious hereditary condition that generally affects only a few individuals within the same family. Its clinical onset most often occurs between the tenth and twentieth year of life. The disease is characterized by a very slowly progressive bilateral visual loss, especially marked under low lighting conditions (nyctalopia) at the beginning stage. Little by little, vision diminishes and the person with the condition finds reading increasingly difficult. At the end of its progression, reading becomes impossible due to the loss of the entire central visual field (central scotoma).
Medical treatment is unfortunately ineffective, since it is a genetic disease. However, the use of visual aids (illuminated magnifiers, electronic magnifying systems through which the disabled individual can read text on a television screen) is a valuable means that allows the person with the condition to have a nearly normal social life for a relatively long period.