Do eyeglasses act as a shield against SARS-CoV-2 infection? Maybe—or maybe not

There is inconclusive evidence that wearing one’s eyeglasses can lower their chances of contracting COVID-19, according to a recent study.

In a cohort of 1,279 employees in Denmark and 841 in Sweden, the use of eyeglasses was inversely associated with COVID-19 infection in the Swedish cohort (odds ratio [OR], 0.61, 95 percent confidence interval [CI], 0.37–0.99; p=0.047; seroprevalence, 9.3 percent) but not in the Danish cohort (OR, 1.14, 95 percent CI, 0.53–2.45; p=0.73; seroprevalence, 2.4 percent) in adjusted analyses. [JAMA Ophthalmol 2022;doi:10.1001/jamaophthalmol.2022.3234]

However, when the estimate in the Swedish cohort was adjusted for confounding factors, such as age, sex, job function, and number of workday contacts in Sweden, the observed association was attenuated (OR, 0.64, 95 percent CI, 0.37–1.11; p=0.11).

In both unadjusted and adjusted analyses stratified by job function, wearing eyeglasses showed a protective association with COVID-19 infection among office workers in the Swedish cohort (OR, 0.20, 95 percent CI, 0.06–0.70; p=0.01) but not among other job functions (ambulance staff: OR, 0.83, 95 percent CI, 0.41–1.67; p=0.60; healthcare staff: OR, 0.89, 95 percent CI, 0.35–2.30; p=0.81).

The association remained null in the Danish cohort, where COVID-19 prevalence was lower (2.4 percent).

“We believe the differences in seroprevalence and general society preventive measures between the countries were part of the reason that the findings in Sweden could not be replicated in Denmark. An explanation could be that wearing one’s own glasses mainly provides protection in closed environments with high viral load, which are more likely to occur in areas with high prevalence and in the absence of other personal protective equipment (PPE),” the investigators said. [Emerg Infect Dis 2020;26:1678-1685]

“Eyeglasses cannot be considered complete eye protection but might reduce both airborne ocular exposure and indirect transmission from less spontaneous self-touching of one’s eyes, thereby limiting nasolacrimal viral flow to nasopharynx,” they added. [Ocul Surf 2021;19:176-182; Ocul Surf 2021;21:64-65]

Furthermore, the investigators noted no significant differences in the risk of COVID-19 infection among people wearing eyeglasses and users of contact lenses or reading glasses as opposed to nonusers, which somehow provides support to the approach of grouping eyeglasses, contact lenses, and reading glasses users together in the primary analyses.

The study was conducted during the first wave of the COVID-19 pandemic (June to August 2020) in Denmark and Sweden—a time when PPE was not recommended for the general population. Furthermore, the participants comprised individuals among the general population in employment with a comparable socioeconomic status but different job functions and workday exposures.

“With the inclusion of different job functions, this present study allowed for evaluation of both persons with frequent COVID-19 exposure during work hours who wore PPE (ambulance personnel) and persons with less frequent but not PPE-protected exposures (office staff),” according to the investigators.

In the overall population, 60.4 percent were men, 20.5 percent were aged <40 years, 57.0 percent were aged 40–60 years, and 22.5 percent were aged >60 years. There were 829 (64.8 percent) and 619 (73.6 percent) individuals in the Danish and Swedish cohorts who wore glasses.

Despite the inconclusive results, the investigators acknowledged that the biological plausibility of an association between eyeglasses and COVID-19.

Wearing one’s eyeglasses, according to them, is a safe and inexpensive additional protection, which should be considered in disease-preventive strategies. “This is supported by evidence that oculotropic respiratory viruses, such as coronavirus, in general might be highly contagious by an ocular pathway.” [Ocul Surf 2021;19:176-182; Microbiol Mol Biol Rev 2013;77:144-156]