Severity of familial isolated retinitis pigmentosa across different inheritance patterns among an Asian Indian cohort.

PURPOSE To predict the progression to legal blindness in patients with isolated inherited retinitis pigmentosa. METHODS This retrospective study evaluated patients with isolated inherited retinitis pigmentosa for age at onset, duration of the disease, and best-corrected visual acuity in an Asian Indian cohort. The Mann–Whitney U test was used to analyze the variables. RESULTS Of 134 patients evaluated, 72% were autosomal recessive, 17% were autosomal dominant, and 11% were X-linked recessive pedigrees. Median age at onset was 8 years for X-linked recessive, 11 years for autosomal recessive, and 21 years for autosomal dominant disease, which was statistically significant. The refractive error due to axial myopia was significantly high in X-linked recessive (−3.50 diopter sphere) compared to autosomal recessive (−1 diopter sphere) and autosomal dominant (0.00 diopter sphere) cases (P < .000). Legal blindness occurred in 50% of X-linked recessive and autosomal recessive cases but in only 32% of autosomal dominant cases. CONCLUSION Identifying the gene defects involved in this cohort will help understand the phenotype variability.