Glasses lenses is the original material used in first eyewear made by mankind. Glass lenses are heavily used up until the 1970s where plastic lens made of acrylic took over as the injection industry matured thought the ages. Ever wonder why the lens to old school glasses does not scratch easy? Answer is that the true advantage of glasses lenses is that it provides superior scratch resistance ability. On the down side, glasses lenses are heavier, and does not offer superior impact resistance when compared to plastic lenses made of acrylic or polycarbonate.