Decline of Visual Function and Risk of Legal Blindness With Age in RPGR-Associated Retinal Degeneration: A Multicenter Study

Background: This retrospective multicenter longitudinal analysis analysed the loss trajectory of best recorded visual acuity (BRVA) and Goldmann visual field (GVF) in RPGR-associated retinal degeneration (RPGR-RD). Methods: Patients with genetically confirmed RPGR-RD were classified into rod-cone (RC), cone/cone-rod (CR) and female-carrier phenotypes. BRVAs and GVFs for both eyes were captured at each clinical encounter. Scatterplots of BRVA versus age and GVF versus age were overlaid with local polynomial smoothers to show the loss trajectory. Results: Two hundred eighty-one patients were identified, including 220 males (158 RC, 44 CR, 18 uncategorized) and 61 female carriers. For the RC group, mean ± SD (range) age of first contact in SOURCE was 24.8 ± 17.2 years (0–69), duration of follow-up was 6.0 ± 5.2 years and at some point during the study, 36/142 (25%) had legal blindness by BRVA and 57/108 (53%) by GVF. Median age of first record of blindness by GVF was 31 years (95% CI, 27–35 years) and by BRVA was 47 years (95% CI, 43–52 years); GVF steeply declined after age 20. For the CR group, mean age of first entry in SOURCE was 32.4 ± 18.8 years (1–66), duration of follow-up was 4.8 ± 3.6 years and 9/42 (21%) had legal blindness by BRVA at ≥ 1 visit. The median age of first record of blindness by BRVA was 60 years (95% CI, 51–73 years). Conclusions: All phenotypic groups of RPGR-RD experienced longitudinal loss of BRVA and GVF. Rapid decline in GVF for the RC phenotype suggests that intervention may be most effective prior to this window.