Prognosis

RP is a progressive disease with an exponential decline in remaining visual field area (estimated at 3-13% loss annually) and ERG amplitude (estimated at 9-19% loss annually). The rate of progression and degree of visual loss varies from person to person. Most individuals with RP are legally blind by age 40 due to severely constricted visual fields (central visual field of less than 20 degrees in diameter). Loss of vision eventually leads to bare or no light perception, posing a continuous threat to patients' independence.

According to some studies, individuals with adRP have the best prognosis, with the majority of those younger than age 30 years having a visual acuity of 20/30 or better. Males with xlRP have the worst prognosis, with all individuals older than age 50 years having a visual acuity lower than 20/200. Individuals with arRP and RP with a single occurrence in the family are intermediate in severity. Other investigators, however, do not confirm the correlation between visual impairment and genetic subtype.