Risk of Endophthalmitis Based on Cumulative Number of Anti-VEGF Intravitreal Injections

Abstract

PurposeTo determine the rate of endophthalmitis in eyes undergoing intravitreal injections (IVI) of anti-vascular endothelial growth factor (VEGF) based on cumulative number of injections per eye. DesignRetrospective cohort study ParticipantsPatients from a single center undergoing IVI of ranibizumab, aflibercept, and/or bevacizumab MethodsEyes were divided into quartiles based on injection number causative of endophthalmitis between January 1, 2011 and June 1, 2022. Main outcome measuresInterquartile clinical outcomes and cumulative risk of endophthalmitis per injection and per eye ResultsA total of 43,393 eyes received 652,421 anti-VEGF injections resulting in 231 endophthalmitis cases (0.035% per-injection, 1 in 2857), of which 215 were included. The cumulative endophthalmitis risk increased from 0.0018% (1 in 55,556) after 1 injection to 0.013% (1 in 7692) after 11 injections (0.0012 percentage point change in risk per injection), vs. 0.014% (1 in 7143) after 12 injections to 0.025% (1 in 4000) after 35 injections (0.00049 percentage point change in risk per injection), vs. 0.025% (1 in 4000) after 36 injections to 0.031% (1 in 3226) after 66 injections (0.00017 percentage point change in risk per injection), vs. 0.031% (1 in 3226) after 63 injections to 0.033% (1 in 3030) after 126 injections (0.000042 percentage point change in risk per injection) (p <0.001). Similarly, the cumulative endophthalmitis risk per eye increased from 0.028% (1 in 3,571) to 0.20% (1 in 500) between injections 1-11 (0.018 percentage point change in risk per injection), vs. 0.21% (1 in 476) to 0.38% (1 in 263) between injections 12-35 (0.0075 percentage point change in risk per injection), vs. 0.38% (1 in 263) to 0.46% (1 in 217) between injections 36-66 (0.0026 percentage point change in risk per injection), vs. 0.46% (1 in 217) to 0.50% (1 in 200) between injections 67-126 (0.00063 percentage point change in risk per injection) (p <0.001). ConclusionsThe cumulative endophthalmitis risk per injection and per eye increased with greater number of injections received but appeared to do so at a higher rate during earlier injections and at a lower rate further into the treatment course.