. . . "Knowing something about the types of frames, lenses and coatings can help you understand your options and sense whether a store or website is trying to sell you more than you need.When Consumer Reports ordered glasses with a simple, single-vision prescription, one online shop automatically checked the box for $40 polycarbonate lenses, when $10 CR-39 lenses were just fine. ??? Get your doctor???s r" . .