Endophthalmitis Rates After Vitrectomy Up, Linked With Masking

Ophthalmology office
Ophthalmology office. Fundus made with a Volk lens (without contact with the cornea). This technique allows a very fine analysis of the details of the fundus. Masked patient and doctor – Covid 19. (Photo by: Pascal Bachelet/BSIP/Universal Images Group via Getty Images)
Infection rates have increased since the start of the COVID-19 pandemic, with the largest rise seen in patients who underwent vitrectomy without cataract surgery.

An increase in the incidence of endophthalmitis following vitrectomy between 2019 and the period between July 2020 and June 2021 suggests an association with increased mask wearing during this period, according to a study from a Japanese research group that was published in the British Journal of Ophthalmology

In this retrospective study, researchers examined participants who underwent vitrectomy from 31 ophthalmological institutions in Japan. The study used cataract surgery results as a control and divided participants by whether they underwent  vitreous surgery alone, cataract surgery alone, or simultaneous cataract and vitreous surgeries. They also noted whether surgeries occurred in 2019 (the pre-COVID-19 cohort), or between July 2020 and June 2021 (the COVID-19 cohort). Researchers also recorded the pathogenic cause of each case of endophthalmitis. 

They found a total of 16,568 vitrectomies in the pre-COVID-19 period and 14,929 vitrectomies in the COVID-19 period. The study authors found a significant difference in postvitrectomy endophthalmitis in the pre-COVID-19 cohort (18, 0.11%) vs the COVID-19 cohort (31, 0.21%)  (P =.031). In the pre-COVID-19 cohort, 8704 participants underwent combined vitrectomies and cataract surgery while 7696 participants underwent vitrectomy alone. In the COVID-19 cohort, 7233 underwent combined procedures while 7696 underwent vitrectomy alone. The incidence of pre-COVID-19 endophthalmitis (13, 0.15%) vs COVID-19 endophthalmitis (17, 0.21%) was not significantly different for those who underwent phacovitrectomy (P =.360). However, for patients who underwent vitrectomy alone, endophthalmitis rates were significantly higher in the COVID-19 cohort (14, 0.19%) compared with the pre-COVID-19 cohort (5, 0.064%) (P =.036).  

The same difference was not found in the control group. A total of 32,839 cataract surgeries were performed during the pre-COVID-19 period and 28,061 during the COVID-19 mask period. In the pre-COVID-19 cohort, 12 (0.037%) developed endophthalmitis, compared with 12 (0.043%) in the COVID-19 cohort (P =.838). 

Pathogens were identified in 4 of the 18 pre-COVID-19 group and included 3 cases of Staphylococcus aureus and 1 case of Staphylococcus auricularis. In the COVID-19 cohort, 9 of the 31 eye with endophthalmitis were culture positive, including 5 cases of Staphylococcus, 2 cases of Streptococcus, 1 case of Enterococcus faecalis, and 1 case of Proteus mirabilis. In the COVID-19 cohort, 3 patients had oral bacteria, compared with none of the pre-COVID-19 cohort.  

The presence of oral bacteria found in the cultures collected from the COVID-19 cohort suggests that masking is linked to the increase in postvitrectomy endophthalmitis, researchers state. They suggest that the use of masking will continue because of the ongoing COVID-19 pandemic and urge physicians to instruct and practice proper mask wearing for and around patients at an increased risk for developing endophthalmitis, such as those undergoing vitrectomy. 

A limitation reported by researchers is the possible bias that comes with conducting retrospective studies. Another limitation is the choice to allow diagnosis of endophthalmitis to the patient’s treating physician, not using any exclusion criteria in the study. Also, the study authors note that stress and anxiety, healthcare worker burnout, and participant comorbidities could contribute to the increased rate of endophthalmitis during the COVID-19 period. A fourth limitation is the low rate of culture positive endophthalmitis, which could be due to the Japanese Health System’s rapid response to suspected endophthalmitis using antibiotics.  

“The significant increase of endophthalmitis after vitrectomy during the COVID-mask period indicates that clinicians need to follow these patients more vigilantly and instruct patients on the proper method to wear masks,” according to the researchers.


Sakamoto T, Terasaki H, Yamashita T, et al. Increased incidence of endophthalmitis after vitrectomy relative to face mask wearing during COVID-19 pandemic. Br J Ophthalmol. Published online June 21, 2022. doi:10.1136/ bjophthalmol-2022-321357