Rain-X is designed specifically to work with glass, not plastics or lexan that are typically used for eye glasses.

Maguiar's makes a plastic polish specifically designed for clear plastic. https://www.meguiars.com/automotive/...0-10-oz-liquid

We also use Maguiar's on our aircraft windscreens (they don't have any wipers, and rely on the speed of the aircraft to shed water).

That's the best I've found. I use it on inexpensive safety glasses that I buy from Home Depot. I use the glasses on my bicycles, and my motorcycles. It beads water almost as good as Rain-X on a windshield, and it's pretty good for anti-fogging as well. For just anti-fog, though, plain dish soap seems to work better. It needs to be applied more frequently, but it is cheap and easy, so who cares.