1. In a retrospective study of about 30,000 patients, the incidence of post-vitrectomy endophthalmitis increased significantly from 0.11% to 0.21% during the COVID-19 period.

2. A small portion of COVID-19-period post-vitrectomy endophthalmitis cases were found to be due to oral bacterial flora.

Evidence Rating Level: 2 (Good)

Study Rundown: Endophthalmitis, or inflammation of the eye typically due to infection, is a rare but serious complication of ocular surgeries, including vitrectomy. Past studies in the setting of non-operative intravitreal injections have found mixed results on the relationship between patient face mask wearing and endophthalmitis risk. This multicenter study aimed to assess the effect of mask use on risk by comparing patients who underwent vitrectomy before and during the COVID-19 pandemic. Among about 16,500 vitrectomy patients in the pre-COVID-19 group, 18 had endophthalmitis for a rate of 0.11%. Among about 15,000 in the COVID-19-period group, 31 had endophthalmitis for a rate of 0.21%. All 4 culture-positive cases in the pre-COVID-19 group were due to staphylococci, while 4 of the 9 culture-positive cases in the COVID-19-period group were due to other bacteria, including 4 due to bacteria indigenous to the oral cavity. Endophthalmitis cases after cataract surgeries were examined over the same period in the same centers, and there was no significant difference in incidence. Overall, this study makes a compelling but incomplete case for mask wearing as a risk factor for post-vitrectomy endophthalmitis. The retrospective design and use of time periods as proxies for differences in mask behavior limit interpretation. Though the culture data aligns with a role for masks, the number of cases caused by oral flora and the number of cases with any identified pathogen at all were both very small. Based on this study, instruction for vitrectomy patients on proper mask wearing to prevent flow of air and pathogens toward the eyes would be appropriate, but the general risk from avoiding masks would still seem to be larger than the risk from wearing them.

Click to read the study in BJO

Relevant Reading: Postoperative endophthalmitis: A review of risk factors, prophylaxis, incidence, microbiology, treatment, and outcomes

In-Depth [retrospective cohort]: Patients from 31 institutions in Japan were included. Patients in the pre-COVID-19 group underwent vitrectomy during 2019; those in the COVID-19 period between July 2020 and June 2021. Post-vitrectomy endophthalmitis was defined as occurring within 42 days of surgery. The odds ratio for the incidence of endophthalmitis in the COVID-19-period group as compared to the pre-COVID-19 group was 1.913, with a 95% confidence interval of 1.078-3.394. Among cataract surgery patients, rates of postoperative endophthalmitis were 0.037% and 0.043% in the pre- and COVID-19 periods, respectively. Cases after vitrectomy alone constituted most of the increased incidence in post-vitrectomy endophthalmitis, while cases after combined vitrectomy and cataract surgery remained relatively stable between study periods. There were no significant differences in numbers of patients undergoing each type of procedure between groups.

Image: PD

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