Fogged up eyeglasses happen when you step from one extreme temperature into another, like stepping out of a heated car and into the snowy outdoors. You can keep your glasses from fogging up and impairing your eyesight by using techniques designed to prevent moisture from building up on glass. These same techniques work with eyeglass lenses made of plastic too.
Shaving Cream
Shaving cream applied to a bathroom mirror will prevent it from fogging up while you take a shower. This same method works well on eyeglasses too. Apply a thin film of shaving cream to the outer and inner surface of your eyeglasses, then wipe it away with a paper towel. The invisible residue left behind will keep moisture off your glasses and prevent blurred vision.
Rain Solvent
A number of windshield solvents on the market help keep a car’s windshield moisture-free during the rain, preventing water from sticking to the windshield and fogging it up while you drive. When rain hits a windshield protected by one of these solvents, drops of water roll off the glass without streaking. A rain repellent windshield solvent works well on eyeglasses too because it will remain on your lenses through several wearings. You can find these solvents at most auto supply stores.
Saliva
Saliva may not seem like a cleaning solution, but its natural properties work well at preventing fog from building up on glass. Rub a bit of saliva over the inside of your glasses. The next time you step into the cold, the moisture should slick away. It’s a trick underwater divers employ to keep their goggles from fogging up and impeding their vision. You may need to reapply saliva after a short period of time because its effects dissipate quickly.