The role of topical antibiotic prophylaxis to prevent endophthalmitis after intravitreal injection.

Objective: To compare the incidence of endophthalmitis after intravitreal injection with and without topical postinjection antibiotic prophylaxis.

Design: Retrospective case-control study.

Participants: All patients treated with intravitreal injection of ranibizumab, bevacizumab, or aflibercept for a variety of retinal vascular diseases at a single, large retina practice between January 1, 2009, and October 1, 2012, were included.

Methods: The total numbers of patients and injections were determined from a review of billing code and practice management records. Endophthalmitis cases were determined from billing records and from an infection log. All cases of endophthalmitis were confirmed with chart review. A 28-month period when topical antibiotics were prescribed after intravitreal injection was compared with a 9-month period when topical antibiotics were not prescribed. Patients treated during an 8-month transition period were excluded to allow for the conversion of antibiotic prescription practices.

Main Outcome Measures: Incidence of endophthalmitis, visual acuity outcomes, and microbial spectrum.

Results: During the study period, a total of 117 171 intravitreal injections were performed (57 654 injections during the topical antibiotic period, 24 617 during the transition period, and 34 900 during the no-antibiotic period), with a total of 44 cases of suspected endophthalmitis (0.038%; 1 in 2663 injections), 17 of which showed culture-positive results (0.015%; 1 in 6892 injections). During the 28-month topical antibiotic period, there were 28 cases of suspected endophthalmitis (0.049%; 1 in 2059 injections), 10 of which showed culture-positive results (0.017%; 1 in 5765 injections). During the 9-month no-antibiotic period, there were 11 cases of suspected endophthalmitis (0.032%; 1 in 3173 injections), 4 of which showed culture-positive results (0.011%; 1 in 8725 injections). Topical antibiotic use was associated with a trend toward increased risk of suspected endophthalmitis (odds ratio [OR], 1.54; 95% confidence interval [CI], 0.77-3.10) and culture-positive endophthalmitis (OR, 1.51; 95% CI, 0.47-4.83).

Conclusions: The incidence of endophthalmitis after intravitreal injection is low. Using postinjection topical antibiotic drops does not reduce the risk of endophthalmitis developing and is associated with a trend toward higher incidence of endophthalmitis.