MARY LOUISE KELLY, HOST:
Way to go. You're wearing your homemade mask. But then that moment you put your glasses on, they fog up. Surgeons like Dr. George Yang deal with this all the time.
GEORGE YANG: What the heck is going on? Why does it keep fogging up like this?
AILSA CHANG, HOST:
Well, there is a simple fix. All you need is soap and water. Here's optometrist Joseph Allen.
JOSEPH ALLEN: The best type of dish soap to use is the original type of Dawn dish soap. If you use anything that says for sensitive skin or has some sort of lotion in it, don't use that. That'll actually just get stuck on the lenses and smear it even more. You just use a single drop on both sides of the lenses, rub it in with your fingers, and then go ahead and rinse off.
CHANG: He says what's left behind is a transparent layer that protects your specs from temperature changes or...
(SOUNDBITE OF SHAVING CREAM)
KELLY: Shaving cream has the same effect. Apply and wipe off.
CHANG: Another trick to try - squish a folded tissue between your mouth and the mask. It will absorb the warm, moist air and prevent your lenses from clouding up.
KELLY: Or maybe just leave your glasses off. You can pretend you're living in a cloudy impressionist painting. [POST BROADCAST CORRECTION: In this report, we mischaracterize Joseph Allen's use of Dawn dish soap on eyeglasses. While many think Dawn helps keep glasses from fogging up, Allen is suggesting it as a way to clean glasses — not as a way to defog them.] Transcript provided by NPR, Copyright NPR.