The study involving 276 patients hospitalised with Covid-19 in Suizhou, China, found that the proportion of daily wearers of eyeglasses was lower than that of the local population (5.8 per cent vs 31.5 per cent).
“We hypothesized that eyeglasses prevent or discourage wearers from touching their eyes, thus avoiding transferring the virus from the hands to the eyes,” the researchers wrote in a paper published in the journal JAMA Ophthalmology.
Studies have shown that normal people will involuntarily touch their eyes about 10 times per hour.
Eyes usually lack protection, and an abundance of the SARS-CoV-2 receptor angiotensin-converting enzyme 2 has been found on the ocular surface, through which SARS-CoV-2 can enter the human body.
“SARS-CoV-2 may also be transported to the nasal and nasopharyngeal mucosa through continuous tear irrigation of the lacrimal duct, causing respiratory infection. According to available statistics, nearly 1 per cent to 12 per cent of patients with Covid-19 have ocular manifestations,” the researchers argued.
The novel coronavirus was detected in tears or the conjunctival sacs of patients with Covid-19 and some ophthalmologists were reported to be infected during routine treatment.
“Therefore, the eyes are considered an important channel for SARS-CoV-2 to enter the human body. For daily wearers of eyeglasses, who usually wear eyeglasses on social occasions, wearing eyeglasses may become a protective factor, reducing the risk of virus transfer to the eyes and leading to long-term daily wearers of eyeglasses being rarely infected with Covid-19,” said researchers.
Presently, many Covid-19 guidelines state the need to pay attention to preventing infections through the eyes, but most people only focus on wearing masks and home isolation, ignoring recommendations such as washing hands frequently and avoiding touching the eyes with the hands..
The results of this study can be used as evidence of the importance of these two recommendations.
The new study “is provocative and raises the possibility that use of eye protection by the general public might offer some degree of protection from COVID-19,” Dr Lisa Maragakis, an associate professor of medicine and epidemiology at Johns Hopkins University School of Medicine, who was not involved in the study, wrote in an editorial accompanying the study.
Maragakis, however, cautioned that the study found only an association and cannot prove a “cause-effect” relationship between wearing glasses and being protected from Covid-19.
The numbers of patients who wear eyeglasses and long-term wearers were also limited, which limits the extension of the results to a larger population.
Still, the study found that the proportion of inpatients with Covid-19 who wear eyeglasses for extended daily periods was lower than that of the general population, suggesting that daily wear of eyeglasses is associated with less susceptibility to the coronavirus infection.
“These findings suggest that the eye may be an important infection route for Covid-19, and more attention should be paid to preventive measures such as frequent hand washing and avoiding touching the eyes.”