Researchers in China have found that people who wear glasses seem to have a lower risk of contracting COVID-19. The author of the study, published in JAMA Ophthalmology, pointed out that since the Wuhan coronavirus outbreak in December 2019, few patients with glasses have been hospitalized due to COVID-19. For further investigation, they collected data on wearing glasses of all COVID-19 patients as part of their medical history.
Their small study found that of the 276 patients who received COVID-19, only 16 (5.8%) wore glasses for more than 8 hours a day. When they determined that all these patients were myopia patients, they then raised the proportion of myopia (myopia) patients in Hubei Province where the hospital is located. They found that this number is much larger (31
This is a fascinating observation, but like all individual studies, the results must be treated with caution. Although eye protection has always been an important part of personal protective equipment (PPE), the magnitude of the difference in this research report is doubtful. This is not to say that the results may not be true, but that we should not start recommending large-scale behavior changes (for example, wearing goggles next to our masks) until they are independently confirmed.
Is the eye the window of the virus?
One of the key steps of any virus infection is to enter the body first. Although most of our body is covered by protective skin, which is very effective in preventing viruses or bacteria from entering our body, a thinner “membrane” covers our respiratory tract, digestive system and eyes. The function of these thinner membranes is to allow external substances such as oxygen and food to enter the eyes. For the eyes, light enters our body. Unfortunately, the virus has learned to use these entry points.
This is why PPE aims to protect these entry points by using masks, goggles and protective clothing. However, although we might think that the main attack on these areas comes from virus particles that spread through the air as aerosols, the main way for virus particles to reach these weak points is actually through our hands. Therefore, COVID-19 recommends that you wash your hands frequently for 20 seconds or longer and avoid touching our faces.
Therefore, it makes sense that covering our eyes with glasses can provide additional protection, not only to prevent the virus carried in the breath of others, but also to prevent the wearer from touching the eyes. Indeed, as early as February, there were reports that people were infected with COVID-19 by improperly protecting their eyes in medical institutions. It is also known that there are similar entry points (ACE-2 receptors) in the human body caused by coronaviruses in the eyes.
Should we start wearing goggles?
A key part of explaining any evidence provided by observational research is to remember that association (two things happening at the same time) does not necessarily imply causation (one thing leads to another). To test causality, a controlled experiment or test is now required.
Ideally, this would follow two carefully matched groups-some with glasses, some without glasses-to see which group has a higher infection rate. The evidence from such controlled trials will always be much stronger than the evidence from observational studies (such as recent papers).
We must also note that the authors of this study have listed many shortcomings. This is a small study conducted on a single site. The researchers’ data on the general population comes from an earlier study that did not exactly match the sample (age, demographics and other factors) with the sample of COVID-19 admitted to the hospital. They cannot guarantee that all myopia in the general population wear glasses for more than 8 hours a day.
Therefore, although this new study is very interesting, there are still many reasons to be cautious about this result. Of course we need more data before we can make any suggestions about wearing goggles next to the mask.