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Chinese scientists say people who wear glasses may be less likely to be infected with the coronavirus. The lower number of infections is of course not caused by a visual defect, but by the wearing of lenses. Unfortunately, studies conducted on a small group of patients have not been independently confirmed so far. That is why the medical world approaches them with a distance and does not plan to encourage us to put on protective glasses or goggles prophylactically.
- Only 16 out of 276 coronavirus patients from a hospital in Hubei Province wore glasses for more than eight hours a day
- For now, it is not certain whether wearing glasses actually prevents SARS-CoV-2 infection
- We know that a hand-borne virus enters the body when we touch our eyes
- The evidence from observational studies is weaker than that from controlled studies
- You can find more such stories on the TvoiLokony home page
The authors of the study, published in September in the eye journal JAMA Ophthalmology, noted that few COVID-2019 patients wearing glasses have been admitted to hospital since the Wuhan coronavirus outbreak in December 19. So they decided to interview everyone who was hospitalized about glasses.
They found that only 16 (5,8 percent) of 276 coronavirus patients wore glasses more than eight hours a day. The next step was to establish that they were all nearsighted.
Therefore, scientists decided to check the percentage of people with myopia in the Hubei province where the hospital is located. It turned out to be 31,5 percent. Thus, the percentage of myopic people hospitalized for COVID-19 was more than five times lower than the province’s population.
The results of the Chinese study are intriguing, but as with all individual studies, they should be treated with caution. While eye protection is an important part of personal protection, the difference in infection levels reported in the study is puzzling… This doesn’t mean that the results are a stretch, but until confirmed in subsequent analyzes, experts do not recommend wearing glasses with a mask.
One of the key moments of any infection is the entry of the pathogen into the body. Most of our body is covered by skin, which effectively traps viruses and bacteria. On the other hand, much thinner “membranes” cover the respiratory tract, digestive system and eyes. Their role is to let elements such as oxygen, food and, in the case of the eyes, light pass through the body. Unfortunately, viruses have learned to use this path and that is why we cover our nose, mouth and eyes with personal protective equipment.
We are attacked by airborne aerosol viruses, but they reach poorly protected places mainly through our hands. Hence the known advice – to wash your hands frequently for at least 20 seconds and avoid touching your face.
Glasses can also provide additional protection, preventing infection from being transmitted through the breath and by touching the eyes. It is known that the coronavirus-preferred sites for entry into the body (ACE-2 receptors) are also present in the eyes. In February, cases of people infected with COVID-19 were reported due to inadequate eye protection in healthcare facilities.
When interpreting observational studies, we must remember that correlation (two things going together) does not necessarily mean causation (one thing causes the other). A controlled study is needed to check causality.
In this case, it would be appropriate to follow two carefully selected groups of people – one would have glasses and the other would have glasses – to see which of them is more likely to get infected. The evidence from such a study will always be stronger than that from observational studies. Other weaknesses of the Chinese study should also be noted – it was conducted only in one place on a small group of people.
The population data of Chinese scientists came from a much earlier study on a sample that was not exactly matched (in terms of age, demographics, and other factors) to the sample hospitalized for COVID-19. In addition, it cannot be guaranteed that all short-sighted people in this population wore glasses for more than eight hours a day.
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