The use of eye protection to reduce transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is questionable. The World Health Organization (WHO) recommends eye protection such as glasses or face shields for healthcare workers caring for patients with 2019 coronavirus disease (COVID-19). However, no such recommendation exists for those caring for COVID-19 patients at home, even when they live in the same room.

In the real world, the impact of eye protection on controlling SARS-CoV-2 infection is uncertain. Australian researchers recently conducted a systematic review of all available research studies on the impact of eye protection on the transmission of SARS-CoV-2.

Study: The effect of eye protection on the transmission of SARS-CoV-2: a systematic review. Image Credit: Boyloso / Shutterstock.com

Criteria for in-depth research, including filtering and data extraction

In their recent article published in the journal Antimicrobial resistance and infection control, The authors explained the details of an in-depth search they performed between January 1, 2020 and June 1, 2021, on the PROSPERO, Embase, PubMed and Europe PMC databases for preprints, as well as the Cochrane Library for clinical studies. In addition, the WHO International Clinical Trials Registry Platform (ICTRP) and ClinicalTrials.gov databases were also searched through June 1, 2021.

The criteria adopted by the authors for this systematic review were as follows: participants were community workers or health workers; interventions included eye protection such as face shields, goggles or modified diving masks; the comparators did not have eye protection, with or without a face shield; and the result was the number of laboratory-confirmed SARS-CoV-2 infections. All comparative studies, including before and after, were included except those that did not provide sufficient data for a comparison between with and without eye protection, laboratory experiments and other eye equipment. that were not intended for the prevention of respiratory viral transmission.

Studies were selected based on titles, abstracts and full texts, as well as risk of bias assessed using the ROBINS-I for observational studies. Confounding factors identified for most studies included variation in risk of COVID-19 before, during, and after the procedure, frequency of testing, comparator, and settings.

Observations

The authors screened 898 articles and included five observational studies published in six reports from four countries in the quantitative analysis. All five studies were conducted in healthcare workers who used eye protection ranging from full-face glasses and goggles to full face shields or visors in addition to approved masks and other infection prevention measures in the corresponding clinical setting.

The three before-after studies and one retrospective cohort study showed a statistically significant and considerable decrease in SARS-CoV-2 infections which promotes eye protection with odds ratios ranging from 0.04 to 0.6, corresponding to risk reductions of 96% to 40%. . In addition, in a case-control study, the reported odds ratio did not favor any eye protection, which could be due to an increase in community transmission.

Any significant meta-analysis was excluded due to the strong heterogeneity between the studies. Because none of the studies were adjusted for potential confounding factors, the risk of bias increased and the certainty of the evidence decreased.

“These studies provide suggestive evidence that face shields offer some protective effect, and that this may be substantial.. “

Discussion

A previous study that looked at observational studies on the impact of eye protection on the outbreaks of SARS-CoV-1 and Middle East Respiratory Syndrome (MERS) showed a decrease in transmission of 66% and 76%, respectively. This result is comparable to the reductions observed in the three before-after studies in this review.

Another study of mannequins also proved that face shields offer better protection than masks. Since these studies did not include viral particles, simulations of human interactions were incomplete.

While these studies showed potential protection for face shields as an adjunct to face masks, they did not say whether the protection came from reduced inhalation or from eye protection. This systematic review suggests that the transmission of SARS-CoV-2 among healthcare workers can be reduced by using eye protection. However, more studies are needed to assess the effect of face shields that are used in place of or in addition to face masks, as well as to compare eyeglasses and face shields with face masks.