By Sayyida Nassimizadeh
Let’s analyse if you can really catch COVID-19 through your eyes.
COVID-19 has changed our world as we know it. But are we aware of all the ways the disease can be spread?
Viruses are more commonly known to be transmitted through coughs or sneezes, where contagious droplets enter through one’s nose and mouth.
Since the pandemic, we have all educated ourselves on the main methods to reduce the spread of infection through the use of regular cleansing with hand sanitisers and thorough hand washing, social distancing, and wearing PPE.
Although these are essential, let’s look at the possibility of COVID-19 being transmitted and its affect on the eyes.
A study led by Lingli Zhou and other researchers and professors from the Department of Ophthalmology at John Hopkins School of Medicine, in Baltimore, found the eyes could ‘serve as a portal of entry as well as a reservoir of person-to-person transmission’ of the coronavirus1. The study looked at whether ocular surface cells contained a key receptor, called ACE2, which allows the coronavirus to attach on and gain entry access into the cell, a method well known to be practiced by cells of the respiratory tract.
The study, which is awaiting a peer-review found an extensive expression of ACE2 receptors across all eye specimens, in particular the superficial layers of both the conjunctiva – the white tissue, and the cornea – the transparent front surface of the eye. In conjunction with this, the researchers found that these ocular surfaces produced an enzyme called TMPRSS2 which allows viruses to enter cells, in particular COVID-192,3.
Although more research is required, the study concluded that the presence of both the receptor and enzyme on ocular cell surfaces supports the hypothesis that the eyes can act as a port of initial entry of COVID-19, as well as act as a secondary site of infection. Though it may not be a common route of transmission, it should not be completely eliminated4 and therefore suitable protection should be maintained to reduce all risk of contracting the virus.
Ocular manifestations of COVID-19 appear as a form of conjunctivitis. This is displayed as a viral infection causing symptoms of red, watery and puffy eyes. Many clinical studies have been carried out, with the highest finding just over 30% of patients testing positive for COVID-19 had ocular signs of viral conjunctivitis, of which 5% may have contracted the virus through their eyes alone5. Other studies have suggested the relation between ocular symptoms and COVID-19 is a lot less. Nevertheless, we should not ignore the risk of possible transmission through the eyes as well as the nose and mouth.
So how can we protect our eyes from transmission?
- Well, firstly, any healthcare professional should wear some form of eye protection, either face shields or eye goggles, when seeing patients, particularly those in close contact with persons who may be infected with coronavirus.
- Secondly, whilst the virus was at its’ peak, it was advised to only attend Ophthalmic practices for emergency appointments only. Primary eyecare services have adapted to use virtual consultations for patients who require ocular attention, an effective way to reduce any need for face to face contact unless necessary. Owing to the ever-evolving circumstances, there have been reports of a gradual reduction in the numbers of COVID-19 cases. This has allowed a relaxing of Government protocol and opening up of non-essential services, enabling Optometrists to see routine private sight tests.
- Thirdly, if you are a contact lens wearer, try reducing your wear time as much as you can and consider wearing your glasses more often. As we are mostly indoors, vanity shouldn’t be an issue, and so your glasses will be a better and healthier substitute for your eyes. If it’s essential for you to wear your contact lenses, make sure you are thoroughly washing your hands before inserting your lenses into your eyes, as any infection on your hand surface can easily contaminate your eye, and result in the inevitable!
While COVID-19 is a novel disease, there is still so much to learn. We do know however that the most common symptoms are a fever, persistent dry cough and anosmia – the loss of smell, but do not fall into the trap of believing whether the presence or absence of certain symptoms will decide if you have the disease or not. In many cases, people have tested positive, with no symptoms at all! Similarly, any eye-related issue may not be a sign of COVID-19, and could be due to allergies, increased screen time, or maybe just due to all the crying you’re doing from romcom binging during lockdown.
References:
- Zhou L, Xu Z, Castiglione GM, Soiberman US, Eberhart CG, Duh EJ. ACE2 and TMPRSS2 are expressed on the human ocular surface, suggesting susceptibility to SARS-CoV-2 infection. Preprint. bioRxiv. 2020;2020.05.09.086165. Published 2020 May 9. doi:10.1101/2020.05.09.086165
- Hoffmann M, Kleine-Weber H, Schroeder S, Kruger N, Herrler T, Erichsen S, et al.SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor. Cell. 2020;181:271–80 e8.
- Matsuyama S, Nao N, Shirato K, Kawase M, Saito S, Takayama I, et al.Enhanced isolation of SARS-CoV-2 by TMPRSS2-expressing cells. Proceedings of the National Academy of Sciences of the United States of America. 2020;117:7001–3
- Xia J, Tong J, Liu M, Shen Y, Guo D. Evaluation of coronavirus in tears and conjunctival secretions of patients with SARS-CoV-2 infection [published online ahead of print, 2020 Feb 26].J Med Virol. 2020;10.1002/jmv.25725. doi:10.1002/jmv.25725
- Wu P, Duan F, Luo C, et al. Characteristics of Ocular Findings of Patients With Coronavirus Disease 2019 (COVID-19) in Hubei Province, China [published online ahead of print, 2020 Mar 31].JAMA Ophthalmol. 2020;138(5):575-578. doi:10.1001/jamaophthalmol.2020.1291