or.....you can do what i did...
i pulled the headlight cover (very CAREFULLY) off of the casing and dried out the inside...i also cleaned and polished the inside using plastic cleaner and polish...then i cleaned and polished the outside..if you want to...you can use a very high grit sand paper and wet sand them just like paint on a car then buff them...whichever you prefer..then use plastic weld (can be bought at pep boys, advance auto, napa etc...) to close the cover back to the casing, then line a small bead of silicone rtv sealant over that so they dont let water in, and smooth the bead so that its flush with headlight cover...allow it to dry for about 4-5 hours before washing or driving in rain just to be safe...then you just clean and polish once a month or more...