Ever go for a jog in your glasses? The heat from your body will fog your lenses and might cause you to trip, fall or step in something gross.
If you are a cook, if you use a dish-washing machine, heck if you wear glasses period, you have felt the interference of fog. That's why Optifog lenses are so great. They actually work exceptionally well and they stop the fog just as advertised. You can hold them right up to a humidifier spewing steam and they will stay totally clear. In my opinion, they are the best recent advance in lens technology because thye effectively solve a common, irritating every-day problem.
They also have a really funny advertising campaign. Check out these three short commercials featuring some embarrassing foggy moments.