Seasonal and Environmental Variations in Endophthalmitis after Intravitreal Anti-vascular Endothelial Growth Factor Injection: A Six-year Review

Purpose To evaluate seasonal and environmental variations on the incidence and outcomes of postinjection endophthalmitis. Methods A single-center, retrospective cohort study was conducted including all patients diagnosed with post-injection endophthalmitis between 2013-2018. Associations between climate variables and endophthalmitis incidence were evaluated. Results Of 423,297 injections administered, seasonal distribution in spring, summer, autumn, and winter was 26%, 27%, 25%, and 22%, respectively. Of 171 cases of endophthalmitis identified, seasonal distribution over the spring, summer, autumn, and fall was 25%, 23%, 26%, and 26%, respectively. Endophthalmitis incidence was not correlated with monthly precipitation (p = 0.45), monthly snowfall (p = 0.49), or monthly temperature (p = 0.65). Worse visual outcomes at initial endophthalmitis presentation were correlated with increased precipitation level (p = 0.025) but were not correlated with snowfall level (p = 0.228) or mean monthly temperature (p = 0.132). Although there were no seasonal variations of visual acuity at endophthalmitis presentation (p = 0.894), odds of final visual acuity returning to within two lines of pre-endophthalmitis visual acuity were worse among patients with endophthalmitis diagnosed in the spring (OR, 0.041; p = 0.016). Conclusion In contrast to previous work on postcataract endophthalmitis, seasonal and weather factors were not associated with post-injection endophthalmitis risk or bacterial species isolated. Visual outcomes at initial endophthalmitis presentation were correlated with precipitation, and worse visual outcomes were seen in patients who developed endophthalmitis in the spring.