Dear Editor,

The eye (other than the respiratory system) is considered an important route of infection of severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) that causes Coronavirus disease 2019(COVID-19). Literature has shown that people typically touch their face about 23 times every waking hour[1]. The eye is rich in the angiotensin-converting enzyme-2 receptor, the SARS-CoV-2 gateway[2].Studies have shown that SARS-CoV-2 was detected in tears of patients with COVID-19, and some ophthalmologists were infected by this route during routine treatment[3–6]. Though the WHO guidelines advocate the usage of goggles or a face shield, the protection provided by them has not been studied extensively. But any protection could, in theory,decrease the susceptibility to acquiring the virus.

A recent study from China concluded that those who used eyeglasses were less prone to contracting COVID-19[7]. An observation in our department and among colleagues/friends who tested SARS-CoV-2 positive also supported this. Additionally, the authors also observed that those following a vegetarian diet were less likely to contract the virus. In order to better understand the relationship between spectacle use,diet, and COVID-19, an observational study was conducted in the Rohtak district of Haryana, India.The ethical waiver was obtained from the Biomedical Research Ethics Committee, Pandit B.D. Sharma,PGIMS, Rohtak. Procedures followed the ethical standards of the responsible committee on human experimentation (institutional and national) and the Helsinki Declaration.

Those presenting to healthcare workers (HCWs) of our hospital or institution were to be tested for SARSCoV-2 and volunteered to participate in our study. At the time of answering our questions, all were unaware of their SARS-CoV-2 status. Nasopharyngeal and throat swab samples were tested by real-time reverse transcriptase-polymerase chain reaction assays(Covidsure 4 Gene Kit, Trivitron Healthcare, India) to detect SARS-CoV-2 infection. They were specifically asked about the length of time that they wore eyeglasses (if at all) during daily activities. Persons wearing spectacles for over 8 hours daily irrespective of the type of refractory error were considered 'regular users'. Their dietary habits were also recorded. Those consuming meat other than plant products were categorized as non-vegetarian while those consuming egg and milk products and no meat were considered vegetarians. Those wearing contact lenses or severely ill were excluded. Participants were not provided with any incentive or compensation to participate in the study.

Of the 922 individuals, 549 (59%) were males and 373 (41%) females. The age range was 1 month to 105 years with a median of 31 years. Among them, 231 were HCWs and 691 were non-healthcare workers(NHCWs). Thirty-eight percent of HCWs and 75 percent of the NHCWs were vegetarian. Fifty-five percent of HCWs and 23 percent of NHCWs used eyeglasses. Overall there were 564 SARS-CoV-2 negative and 358 positive patients. On analysis,neither dietary habits (P=0.45) nor use of eyeglasses(P=0.191) appeared to affect susceptibility to SARSCoV-2 as can be seen inTable 1below. Additionally,gender (P=0.103) also showed no association with the SARS-CoV-2 status, but either male NHCWs(P=0.01) or older subjects (P=0.026) were affected more likely; and HCWs were more susceptible than the general population (P=0.001).

The higher incidence among HCWs and the elderly comes as no surprise. Our study showed that none of the factors (dietary habits, eyeglasses, or gender)appeared to affect susceptibility to SARS-CoV-2,which is contrary to the study published inJAMA Ophthalmology(2020)[7]. That study only considered SARS-CoV-2 positive inpatients, which could have been biased by extrapolating to the entire population,and their finding could be merely due to chance alone.Another setback of the study is that the confounding role of physical distancing and handwashing practice has not been studied. This observational study cannot be used to deduce that there is a fundamental relationship between spectacle use and SARS-CoV-2 infection. Finally, the ineffectiveness of eyeglasses could be due to the inadequate protection offered by spectacles from the sides. There could be a relation between the severity of the disease and use of eyeglasses, which we have not studied. A similar view has been presented in an invited commentary in the same journal[8].

Table 1 SARS-CoV-2 infection in the study group

The eye could be an infection route for SARSCoV-2, but our findings reiterate that more attention is paid to preventive measures such as mask usage,frequent hand washing, and social distancing, apart from eyewear sanitation that may be the weak link in the chain.

Yours Sincerely,

Pradyumna Krishna Majumdar1,?, Vikas Bhardwaj1,Sarika Sharma1, Sarita Majumdar2

1Department of Orthopaedics,

2Department of Nursing,

Post Graduate Institute of Medical Sciences,Rohtak, Haryana 124001,

India.

?Tel: +91-80592-20723,

E-mail: pradyumnakm@gmail.com.