Can wearing glasses protect you from the novel coronavirus? A new study suggests that it may, but the findings come with several limitations. The study, from Chinese researchers, is published in JAMA Ophthalmology.
How does the study make this suggestion?
It is an observational study on a small group — 276 patients of Covid-19 in Hubei, 155 of them male and 121 female. The study examined how many of them wore glasses for more than 8 hours a day. The count was 16 (less than 6% of the patients) and all of them had myopia. The study authors then compared this with the proportion of people with myopia in Hubei province, which was 31.5% based on a previous study. Since the proportion of myopia in the population was much higher than the proportion of Covid-19 patients who had myopia, the researchers suggested that daily wear of glasses is associated with less susceptibility to Covid-19 infection.
How significant is this conclusion?
The authors themselves note limitations:
* It was a single-centre study with a small sample size.
* The proportion in the population of people who wear glasses was based on previous data, not calculated from current local populations.
* The myopia rate obtained in previous studies included a small number of people with myopia who did not wear glasses.
JAMA invited an epidemiologist, Dr Lisa L Maragakis of Johns Hopkins University School of Medicine, to write a commentary on the research. She has advised caution before concluding that people should wear glasses or other types of eye protection in public to prevent Covid-19.
📣 Express Explained is now on Telegram. Click here to join our channel (@ieexplained) and stay updated with the latest
What are the issues flagged in the commentary?
Dr Maragakis expands on the limitations acknowledged by the study authors and cautions against inferring a causal relationship from a single observational study. She notes that there may be an alternative explanation for the findings, “if, for instance, wearing eyeglasses is associated with another unknown and unmeasured factor associated with the risk of Covid-19”.
Also, the investigation took place very early in the pandemic, and the statistics do not include data on handwashing or physical distancing. “This makes it difficult to assess any incremental benefit of eye protection in public settings over and above these basic interventions that are now the mainstay of Covid-19 prevention,” she writes.
While she acknowledges that the observed difference in wearing eyeglasses between the Covid-19 patients and the general population is unlikely to have occurred by chance alone. she stresses that it does not indicate a causal relationship.
Beyond the correlation shown, how can eyeglasses be associated with Covid-19?
Since the pandemic began, it has often been speculated whether the eye is a potential entry point for SARS-CoV-2, the virus that causes Covid-19. However, studies so far have thrown up mixed results. One, posted on the website of the US National Institutes of Health, has reported the expression of the human protein ACE2 in parts of the eye (the virus uses ACE2 to enter the human cell). On the other hand, a study in the Journal of Medical Virology found no significant expression of ACE2 in conjunctival samples.
In her commentary, Dr Maragakis notes that eye protection — goggles, face shield —are an important part of PPE (personal protective equipment) used by healthcare workers. But public health guidelines on Covid-19 do not recommend glasses for the general public.
Dr Maragakis warns of unintended consequences in concluding that people should wear glasses in public to prevent Covid-19. “Wearing goggles, a face shield, or even eyeglasses might pose an increased risk of touching one’s eyes more frequently and potentially contaminating them when removing, replacing, or adjusting the eye protection, especially if a person is not accustomed to wearing them,” she writes.
📣 The Indian Express is now on Telegram. Click here to join our channel (@indianexpress) and stay updated with the latest headlines