Will glasses and a plastic mask keep you safe from Covid-19?

You may think that donning a face mask on your daily commute is enough to keep you, and others, safe from catching coronavirus. But now, new research suggests you should add a pair of specs to your ensemble, too.

According to a study conducted in China, coronavirus patients were five times less likely to wear glasses than the general population. The team, from The Second Affiliated Hospital of Nanchang University, says they believe this is because ACE-2 receptors, which the virus latches onto to enter and infect human cells, can be found in the eyes.

Based on this evidence, the researchers hypothesized that frames “prevent or discourage wearers from touching their eyes, thus avoiding transferring the virus from the hands to the eyes.” This is different from the idea that glasses could stop the virus – which is widely believed to be spread through aerosol droplets caused by coughing and sneezing –  from coming into their eyes.

It isn't the first time that eye health has entered the coronavirus debate. Earlier this year, Dominic Cummings said the reason he decided to take a 60-mile round trip to Barnard Castle, while staying at his parents during lockdown, was to test that his eyesight was safe enough to make the long drive back home to London. This was after his wife became worried about his eyesight after he had suspected Covid-19 a fortnight before.

Boris Johnson, who was hospitalised with coronavirus earlier this year, said that he’s having to wear glasses ‘for the first time in years’ after the illness.

But just how plausible is this new theory? We’ve asked the experts...

Can glasses protect you from coronavirus? 

According to the evidence, they could – although, like all single studies, the findings must be treated with caution. The small study, published in JAMA Ophthalmology, found that only 16 (5.8 per cent) of the 276 patients admitted with Covid-19 wore glasses for more than eight hours a day. As they determined that all these patients were short-sighted, they next looked up the proportion of people with myopia (short-sightedness) in Hubei Province, where the hospital is located.

They found this to be much larger (31.5 per cent), indicating that the proportion of short-sighted Covid-19 hospital admissions was over five times lower than might be expected from that population.

Indeed previous research suggests that there is a small chance that the eyes could act as an entry point for the virus. In March, scientists from the Johns Hopkins University School of Medicine found that eyes produce ACE-2, a protein used by the infection to bind cells, making eyes a target for the virus. In practice, this means if droplets from an infected person’s sneeze or cough were to land on the eye’s surface, the virus could enter the cells there. As far back as February there were reports of people catching COVID-19 by not suitably protecting their eyes in a healthcare setting.

There are problems with this study though. Andrew Bastawrous, an ophthalmologist and an Associate Professor at the London School of Hygiene & Tropical Medicine, says that although the study has "biological plausibility", it must also be treated with caution.

"It's plausible that the virus can transmit through the mucus membranes in the eyes –  that’s the reason why people wear goggles as personal protective equipment (PPE). However, there are no public health guidelines that state people should wear eye protection outside of a clinical setting," he says.

One of the study's limitations is that they're comparing data from two different studies – one which happened decades ago in a different part of China says Prof Bastawrous. "The two comparisons are two groups which you can’t really compare. There could be lots of other alternative explanations for the findings."

He adds that preventive measures, such as wearing a mask, physical distancing, hand-washing and isolating when you're sick, are the most effective ways to reduce transmission.

Previous research shows that there is a small possibility that coronavirus can be spread through tears – which may explain why up to 12 per cent of patients with Covid-19 present with “ocular manifestations” such as redness and swelling.

A study undertaken in March by researchers from Singapore and the UK, which was published in Opthalmology, collected 64 tear samples from 17 patients with Covid-19 from the time they showed symptoms until they recovered about 20 days later. They found that the risk of transmission this way was “low”, and that infection was much more likely to occur through mucus and droplets expelled by coughing or sneezing.

Are face shields more effective than face masks?

They’re a common sight in beauty salons around the UK – but should we all be sporting one too? In the same way that glasses provide a protective barrier for coronavirus droplets entering our eyes, so too might face visors.

Indeed, there is growing evidence that airborne aerosols carrying the coronavirus may play a major role in spreading Covid-19. Although the World Health Organisation doesn't categorise Covid-19 as an airborne disease, many experts believe it could be. One recent study at a hospital in Florida, for example, found that viable Sars-Cov-2 virus could be isolated from air samples up to 4.8 metres (15.7ft) away from infected patients.

In August, Dr Anthony Fauci, an infectious disease expert, told viewers: “If you have goggles or an eye shield, you should use it.” This is because goggles could prevent the lingering airborne particles from entering your eyes and causing transmission.

However, the evidence is mixed. One study by scientists at Florida Atlantic University even found that plastic visors and masks with valves could increase coronavirus transmission rates. This is because even though face shields could block the initial forward movement of an aerosol jet, caused by a cough or a sneeze, the droplets can still spread around the visor quite easily.

Indeed, Prof Bastawrous says that donning things like glasses and face visors "when we aren't accustomed to wearing them" can actually have the opposite effect, leading people to touch their faces more often.

"New glasses wearers will often touch their faces as they get used to wearing them – it’s been shown that as people are getting accustomed to using PPE, it's becoming a point of infection. As you’re trying to put on the gear, if it’s not new or clean, then you’re risking introducing an infection," he says. "Although there may be some theoretical benefit if people go out wearing glasses or visors it may actually put themselves at harm, too."

According to the World Health Organisation, face shields should only be advised "in the context of non-medical mask shortages" and for people who would find wearing a medical mask difficult.

Can you catch coronavirus from earphones?

"I’m yet to hear of any evidence that the Covid virus spreads directly through ears," says Dr Claudia Pastides, of Babylon Health. "Whilst the eyes are anatomically linked to the upper airway via the nasolacrimal duct (a passageway between our eyes and nose), there is no direct passageway between the outer ear and upper airways."

She adds that if you're not "inadvertently touching your eyes, nose or mouth when putting earphones in", are washing your hands regularly and not sharing earphones, then they are an unlikely source of coronavirus.

However, we know that coronavirus can live on hard surfaces like plastic, glass, and wood for three to five days. Practising good hygiene, such as sterilising electronics, and regular hand-washing will go much further than ditching your earphones altogether.