To compare the incidence of endophthalmitis after intravitreal anti-vascular endothelial
growth factor (anti-VEGF) injections with and without patient face masking.
Two-centre retrospective cohort study
Patients receiving a total of 28 501 injections (period 1 before masking: n = 13 863;
period 2 after masking: n = 14 638)
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.
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).
The implementation of patient masking in clinical practice did not significantly alter
the rate of endophthalmitis following intravitreal anti-VEGF injections.