by Peter Urban and Barbara Stepko, AARP, February 26, 2021 (still relevant, and will be for quite a while)
DIY techniques
An easy hack is to place a folded tissue between your mouth and the mask. The tissue will absorb the warm, moist air, preventing it from reaching your glasses. Also, make sure the top of your mask is tight and the bottom looser, to help direct your exhaled breath away from your eyes.
If you are using a surgical mask with ties, a 2014 article in the Annals of the Royal College of Surgeons of England advises going against your instincts. Tie the mask crisscross so that the top ties come below your ears and the bottom ties go above. It will make for a tighter fit.
The Annals of the Royal College of Surgeons of England published an article in 2011 that offered a simple method to prevent fogging, suggesting that, just before wearing a face mask, people wash their spectacles with soapy water, shake off the excess and then allow the lenses to air-dry
“Washing the spectacles with soapy water leaves behind a thin surfactant film that reduces this surface tension and causes the water molecules to spread out evenly into a transparent layer,” the article reveals. “This ‘surfactant effect’ is widely utilized to prevent misting of surfaces in many everyday situations.” Antifogging solutions used for scuba masks or ski goggles also accomplish this. Read the entire article HERE.