Impact of Cataract Surgery on the Risk of Conversion from Dry to Neovascular Age- related Macular Degeneration in the IRIS® Registry

Objective To evaluate the association between cataract surgery and the conversion of dry age-related macular degeneration (AMD) to neovascular AMD (nAMD) and risk factors for nAMD conversion among eyes receiving cataract surgery. Design Retrospective time-to-event study. Subjects Adults in the United States-based IRIS ^® Registry (Intelligent Research in Sight) with dry AMD and cataract surgery after AMD diagnosis. Untreated fellow eyes with dry AMD served as controls for a subset of patients. Methods Eligible eyes were identified using International Classification of Diseases codes and followed for up to 7 years to assess nAMD conversion. Demographic and clinical data were assessed during follow-up. We use proportional hazards models to estimate risk factors for nAMD conversion. Main Outcome Measures Conversion rate from dry AMD to nAMD during study period. Results The full sample included 241,732 eyes (mean age 76 years, SD 7 years, 61% female, 94% White). Smoking status was 65% never, 26% former, and 9.3% active smokers. The subset of patients with one treated and one untreated eye included 25,111 patients. Kaplan-Meier analysis showed 68% event-free survival for nAMD conversion in the cataract surgery treated eyes vs. 32% in fellow untreated eyes at 7 years. Conversion risk was significantly lower in eyes with cataract surgery (Hazard ratio (HR) = 0.49, CI = 0.47-0.52, P < 0.001), controlling for pre-surgery dry AMD stage and visual acuity, as well as observed and unobserved person-level factors. In the full sample, higher conversion risk was associated with worse baseline vision, older age, female sex, smoking, advanced AMD, and White race (P < 0.001). Cataract surgery type was not significantly associated with conversion risk. Conclusion Over a 7-year study period, cataract surgery was associated with a significantly and substantially lower risk of conversion from dry AMD to nAMD. Risk factors for conversion include advanced dry AMD, older age, poorer baseline vision, female sex, and active smoking.