Authors: Shaobo Lei, David Wong.

Author Disclosure Block: S. Lei: None. D. Wong: None.

Abstract Body:

Purpose: To provide microbiological evidence regarding the idea that face masks worn by the patient during intravitreal injection increase the risk of endophthalmitis and to investigate if such a risk can be mitigated by simply sealing the upper edge of the mask with a piece of adhesive tape
Study Design: Experimental research
Methods: The air flow near the eyes were cultured by placing blood agar plates over the eyes for 1 minute while the participants lying supine on an exam chair in an ophthalmology office were instructed to breathe with mouths open. Each participants provided culture samples in three masking conditions: no mask (Condition 1), masked (Condition 2), masked with a piece of adhesive tape sealing the upper edge of the mask (Condition 3). 10 blood agar plates were sampled in each condition on each participant. A total of 300 plates were collected and cultured.
Results: 10 healthy volunteers participated the study. A total of 300 blood agar plates were successfully collected and incubated. The mean of CFU (95% IC) per participant in Condition 1, 2 and 3were 0.60 (-0.001, 1.203), 2.80 (0.727, 4.873) and 0.40 (0.031, 0.769) respectively. Condition 2 is associated with significantly more CFU than condition 1 and 3 (p< 0.05), while the CFU counts in Condition 1 and 3 do not differ from each other (p=1.00).
Conclusions: Our study may have important clinical applications during the on-going Covid-19 pandemic. We demonstrated that mask-wearing increases the bacterial dispersion near the eyes of the mask-wearer themselves, and this risk can be attenuated by sealing the upper edge of the mask with adhesive tape. We recommend taping the upper edge of the mask for all patients receiving intravitreal injection to minimize the risk of post-injection endophthalmitis.