Hot breath escaping from the top of a face mask can cause spectacles or sunglasses to steam up, making it difficult to see clearly.
Eye health UK has compiled these six top tips to help.
1. Keep your lenses clean
Cleaning your lenses with your regular spectacle lens cleaning solution creates a thin film on the surface of the lens that can disperse fine water molecules in your breath and help prevent the lenses misting up.
If you don't have any lens cleaner to hand, try washing your lenses in warm soapy water - washing up liquid works well. Shake off any excess water and leave to air dry (or gentle dry with a soft cloth).
Never use a paper towel or your sleeve to dry your lenses and avoid abrasive cleaners.
2. Apply anti-fog lens coatings
Speak to your dispensing opticians about the various coatings that can be added to your lenses.
3. Seal it up
Use double-sided sticky tape to ensure your mask fits snuggly across the bridge of your nose and cheek bones. This is not recommended for extended wear.
4. A good fit
A well fitted mask will dramatically reduce the amount of air escaping. Masks with a mouldable frame can help you achieve a good fit.
If you are wearing a home-made mask, try sewing a channel along the edge of the mask and inserting a pipe cleaner (or similar) so you can shape the fit around your facial features.
5. Double strap tying technique
A trick used by hospital surgeons is to tie the top straps of a surgical mask firmly below the ears before tying the bottom straps above the ears around the crown of the head. This forms a snug fit across your nose and cheeks and vents air from the side of the mask.
6. Breathe in a downward direction
As a temporary fix you can try breathing downwards so the air you breathe out flows away from your glasses.
Technique: Hold your upper lip over your lower lip. Then blow air downward, as if you're playing the flute.
Remember - always fit your mask to your face, not to the frame of your glasses!