Mother's also has a polish. I happen to have the Meguiar's, I've had the bottle for 10+ years as a little goes a long way. It is a blend of very fine polishing abrasives and a petroleum distillate. Remove the lens from the housing, use a soft toothbrush to remove dirt from the crevices, wash and rinse in lukewarm water, and allow to dry. Then use a very soft COTTON terry cloth to apply polish to the smooth surface of the lens, and rub. Follow the instructions on the label as to drying time and rubbing out, and you will be very pleased with the results.

Meguiar's and Mothers are available in auto parts stores; 3M is found at good auto paint stores. If I was buying now, I'd buy the 3M.