Wearing face coverings to protect oneself from coronavirus can trigger a new medical phenomenon nicknamed 'mask eye', optometrists have warned.
They have issued advice on how to cope with face-covering-associated ocular irritation.
More than one in five people are struggling to maintain healthy eyes while wearing face coverings to reduce the spread of coronavirus, according to research by the College of Optometrists to mark National Eye Health Week.
People in the UK are legally obliged to wear a face covering in settings such as public transport, shops and supermarkets, entertainment venues and places of worship, according to the Government's website.
Daniel Hardiman-McCartney, clinical adviser to the College of Optometrists, said: "As you breathe out, air is directed out of the top of your mask and is blown over the surface of your eye.
Watch: What is the latest guidance on masks?
"This may result in your tears becoming disrupted and evaporating more quickly which can cause discomfort and a gritty feeling where your eyes may become watery and look red or sore."
He said people experiencing eye discomfort should first ensure their mask fits firmly around their nose, so air is forced out at the sides.
Lubricating drops or sprays can also be used to help keep the eye surface moist.
Mr Hardiman-McCartney said: "We know from our own research that 22 per cent of people noticed their vision deteriorate during lockdown, so we are urging these people and anyone who is having issues with their eyes to contact their local optometrist.
"All practices will be following Government guidance and optometrists wearing PPE, to ensure that your visit is safe."
Blinking three or four times and shutting your eyes tightly for a few seconds every 20 minutes can also help naturally refresh the eyes.
Mask-wearers have also struggled with spectacles fogging up and thus not being able to see clearly.
Mr Hardiman-McCartney said: "Glasses get misty or foggy when warm air flows out of the top of your mask when you breathe out.
"The warm air flows over the cooler spectacle lenses causing condensation to form on the lens surface, resulting in misty vision.
"The moist air may also cause your glasses to slip around your nose making them less comfortable."
Wearing a snug face mask can again prevent this from happening by letting air out the sides.
Likewise, making sure your glasses fit properly can stop them from sliding off your face.
Crossing the masks' ear loops or using tape to fasten the top of the mask to your face makes for a tighter fit.
Mr Hardiman-McCartney added: "Wide 2.5cm (about one inch) surgical tape works the best, half on the mask and half on your face, if you're dextrous you can do it on the inside so you don't even see the tape."
Products, including lens cleaners and sprays, anti-fogging wipes and microfibre cloths can also help clear the mist.
Hydrophobic coated lenses, which are easy to clean, are an option for people looking to buy a new pair of specs.
The College of Optometrists also said people should continue to wear a face covering or mask to reduce the spread of coronavirus, regardless of being affected by mask eye.