Inferior intravitreal injection site associated with a higher incidence of post-injection endophthalmitis

AIM: To determine whether inferior injections had a higher incidence of post-injection endophthalmitis than superior injections. The incidence of endophthalmitis is higher for inferior than superior trabeculectomy filtering blebs, possibly due to bacteria pooling in the inferior tear lake. METHODS: A practice-wide database of endophthalmitis cases identified 5 occurring during the two-year study period. A retrospective review of 8 672 injections in 1 121 eyes of 909 patients treated during the same two-year study period was performed in order to assess the injection site location. RESULTS: Five eyes developed presumed infectious endophthalmitis. Eighty percent of endophthalmitis cases were injected inferiorly, even though 84.6% of the total cohort was injected superiorly. The odds ratio of infection associated with inferior injection location is 22.1 (P=0.006). CONCLUSION: Endophthalmitis after intravitreal injection is rare, occurring in only 0.025% of injections overall. Avoiding intravitreal injections in the inferior quadrants may further reduce the rate of endophthalmitis.