Objective: To compare the incidence of endophthalmitis after intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections with and without patient face masking.
Design: Two-centre retrospective cohort study PARTICIPANTS: Patients receiving a total of 28 501 injections (period 1 before masking: n = 13 863; period 2 after masking: n = 14 638) METHODS: Periods before and after implementation of patient masking were compared: period 1 (July-December 2019) and period 2 (July-December 2020). All patients requiring treatment for endophthalmitis following intravitreal anti-VEGF injections were reviewed. Endophthalmitis risks were compared. Statistical simulations were run to determine the number of injections or endophthalmitis cases required to detect a statistically significant difference between both periods.
Results: Five patients (0.036%) had endophthalmitis in period 1 compared with 7 patients (0.048%) in period 2. Odds ratio, 95% confidence interval, for risk of patient masking was 1.326, 0.421-4.179 (p = 0.63). Three patients (0.022%) in period 1 had culture-positive endophthalmitis compared with 2 patients (0.014%) in period 2. Risk of patient masking for culture-positive endophthalmitis was 0.631, 0.105-3.779 (p = 0.61). Assuming similar rates of endophthalmitis, 476,806 injections in both groups would be required to detect a significant difference. Alternatively, assuming that masking would increase endophthalmitis risk in period 2, a significant difference would require twice as many cases (n = 15, 0.102%) for a risk of 2.843, 1.033-7.825 (p = 0.043).
Conclusions: The implementation of patient masking in clinical practice did not significantly alter the rate of endophthalmitis following intravitreal anti-VEGF injections.
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