Wave after wave of COVID-19, and we’re still unable to defend against widespread community infection, even worse with the new omicron variant.
Maybe we’re missing something.
We’re all aware by now that COVID-19 spreads through inhalation of respiratory droplets while close to infected people in crowded and poorly ventilated environments. We also know that we can self-infect by rubbing and touching our eyes, noses, and mouths with SARS-CoV-2-contaminated hands. While inhaling virus-containing droplets is the most important route of infection, we know less about contaminated respiratory and airborne droplets entering through our eyes.
Eyes as a route of viral infection
The Spanish flu of 1918 illustrated that the eyes are a route of infection, when doctors found that protecting the whole face was more effective than just covering the nose and mouth (Maxcy KF The transmission of infection through the eye. JAMA. 1919; 72: 636-639). There is also precedence, as other viruses like adenoviruses, influenza, and the herpes simplex virus infect through the eyes.
So what about COVID-19? In recent studies, researchers have observed reduced COVID-19 spread in healthcare workers wearing goggles or face shields in addition to masks, gloves, and gowns.
How viruses enter the body through the eyes
The eye has a tear film made up of a lipid or oily layer, an aqueous or watery layer, and a mucus layer, which keeps the eye moist and acts as an environmental and immune barrier. The tears wash out foreign materials and contain substances that prevent invasion and infection by microbes. However, sometimes, the lipophilic (lipid-loving) and electrostatic properties of the conjunctiva allow materials and microorganisms to stick to the eye, making it easier for them to enter the body.
The role of COVID-19 spread via the eyes is controversial because we don’t know the extent of spread via the eyes yet, and eye infections in people with COVID-19 are infrequent, suggesting a minor role. However, there is evidence for key features of the eye that make it an easy target.
Firstly, the conjunctiva and cornea have angiotensin-converting enzyme 2 (ACE2) receptors, which bind SARS-CoV-2 and enable its entry into our cells. Secondly, the conjunctiva produces ‘transmembrane serine protease 2’ (TMPRSS2), an enzyme that breaks down and activates viral envelope glycoproteins of SARS-CoV-2 and others, such as Influenza, and MERS, further facilitating cell entry.
Once in the eyes, the virus can migrate to the nose via the tear ducts and potentially spread into the lungs. There is also some speculation that the virus may persist in tears that could become a contamination source.
Eye protection – an extra layer
Should we protect our eyes especially now that there is a new, more contagious variant? Why not – it’s pretty easy to do, and it would be a physical barrier protecting against contaminated droplets through sneezes, coughs and breathing.
Healthcare workers and caretakers should wear eye protection when looking after COVID-19 patients to reduce the transmission risk. But, there are some key issues to consider for the rest of us.
Wearing glasses as a mechanical barrier inhibits eye rubbing and touching. People who wear glasses touch their eyes less than those who don’t. But just wearing a pair of glasses or a face shield may not be enough, as they don’t protect against air currents coming in around the edges. Goggles are more secure, with sealed edges that reduce most air from reaching the eye. But they fog up, obstruct vision, and are uncomfortable for long periods. Also, when worn together with masks, they may interfere with communication and facial recognition. And if they’re irritating, people will take them off, wear them incorrectly, or put them on and off with unwashed hands, making them less effective.
To date, public health agencies like the World Health Organization (WHO) and the Centers for Disease Control (CDC) haven’t recommended eye protection for the general public. However, they do advise healthcare workers to wear goggles or face shields.
Here are some tips to avoid eye contamination
The most crucial strategy is social distancing, careful hand-washing or sanitizing, and not touching your eyes. But touching and rubbing our eyes is such an automatic habit that it’s often hard even to notice that you’re doing it. So, there are other things that you can do:
- Avoid coming in close contact with people who are sick.
- Keep your distance in general.
- Try not to rub your eyes – particularly when you’re COVID-19-positive – use a tissue and be sure to immediately throw it out.
- If you wear contact lenses, use good lens hygiene and consider switching back to glasses as contact lens wearers touch their eyes more often;
- Be sure to use clean hands when removing, replacing, or adjusting glasses or goggles;
- Use a tissue instead of your finger to scratch, touch or rub your eye, or adjust your glasses.
- Wash your hands before and after administering eye drops.
- If you have dry eyes, use moisturizing eye drops to reduce the tendency to rub them.
- Wear glasses or sunglasses with or without corrective lenses in crowded and poorly ventilated areas.
- Wear glasses so that they are on the top edge of your mask to avoid fogging.
- Wear eye goggles, visors, and face shields, together with your face mask, if you’re looking after someone with COVID-19 or have close contact with people as opticians, ophthalmologists, beauticians, or work in a hair salon.
Wearing eye protection can help and certainly won’t hurt. So why not find some iconic glasses like Iris Apfel and Elton John and start a trend?