CR-39 lens, which is a type of plastic, is the most popular type of lens due to its low cost, light weight, and yet high optical quality. In terms of optical quality, it ranks below Polycarbonate lens, but above high-index lens.
Polycarbonate lens, also known as Poly lens, has the ability to block UV rays and is shatter and scratch resistant. Moreover, due to its refractive index, Poly lens provides highest quality vision compared to other lens material. Thanks to their safety, they are a great candidate for use in sports glasses, and glasses for children and teenagers.