Assuming you wear some sort of glasses while riding, they make little plastic "bifocal patches" that you can stick to the inside of sunglasses. They stick on by simply wetting them and pressing them on then letting them dry. I haven't used any for some years now (finally broke down and bought prescription sunglasses) but they worked pretty well. I don't think the optical quality was such that you'd want to read a novel through them, but they were fine for tieing a fishing line.