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Wearing glasses in public for 2 weeks did not protect against SARS-CoV-2 infection, a Norwegian pragmatic randomized trial showed.

Among more than 3,700 participants, 3.7% of those randomized to wear sunglasses or other types of glasses in the community reported a positive COVID test to the Norwegian Surveillance System for Communicable Diseases compared with 3.5% of those in the control group (relative risk 1.10, 95% CI 0.75-1.50), reported Atle Fretheim, MD, PhD, of the Norwegian Institute of Public Health in Oslo, and colleagues.

Yet 9.6% of participants in the intervention group had a positive COVID test result based on self-report compared with 11.5% in the control group (RR 0.83, 95% CI 0.69-1.00), they noted in .

And the risk of respiratory infections based on self-reported symptoms was also lower in the intervention group versus the control group (30.8% vs 34.1%; RR 0.90, 95% CI 0.82-0.99).

"The findings from this first randomized clinical trial of eye protection against viral spread are inconclusive but indicate that wearing glasses in public may protect against respiratory viruses," Fretheim and team wrote.

"Any effect would probably be modest at best, but wearing glasses is simple, low burden, and low cost; has few negative consequences; and may be worth considering as one component in infection control, pending further studies," they added, noting that the most common negative consequence was fogging of glasses when combined with face masks.

Even so, the use of face masks was substantially higher in the intervention group, reported by 39.5% of participants for more than 50% of the time compared with 29.7% of the control group, which the researchers called a "surprise finding."

A previous showed an association between wearing glasses and prevention of SARS-CoV-2, while a recent U.K. cohort study published on the preprint server showed a moderate reduction in risk of COVID-19 for people who consistently wore glasses (OR 0.85, 95% CI 0.77-0.95).

"None of these studies were randomized, and nearly all were conducted in healthcare settings," Fretheim and colleagues wrote. They noted that the results from two randomized trials evaluating the use of face masks were "broadly speaking, in the same range as ours (i.e., consistent with a modest, albeit uncertain, effect.)"

"We are hopeful that others will conduct similar trials that can be synthesized in meta-analyses and provide a more robust body of evidence," they added.

For this study, conducted from February to April, the researchers enrolled 3,717 adults in Norway who did not wear glasses regularly, had no symptoms of COVID, and had not been infected within the last 6 weeks. Mean age was 46.9, and 65.6% were women. All were followed in the national registry, and 86.9% responded to the end of study questionnaire.

Of the participants randomized to wear glasses, 70.5% reported following protocol 50% or more of the time.

The proportion of participants in the intervention group who regularly used public transportation was lower than in the control group (23.1% vs 27.2%, respectively), and similar proportions reported taking a COVID-19 test during the trial period (49.9% vs 49%, respectively).

Fretheim and team noted that the trial was conducted during a time when the Omicron variant was dominant. "It is possible that new variants, or other respiratory viruses, have different modes of transmission," they wrote.

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