They absorb all harmful UV light and can be made with ultra thin edges because of their unique strength. Glass lenses are also available 'with the slimming advantages of High index but are considerably heavier. High index plastic uses less material so they are often lighter in weight. High index lenses absorb 0 harmful UV light and can be tinted to any shade or color. It is generally accepted that ultraviolet rays in' sunlight pose potential harm to the eyes.
Special treatment is available for hard resin lenses that completely blocks hazardous UV light.
Lenses like polycarbonate and high index include built-in UV protection at no extra cost. These coatings are particularly effective for reducing eye fatigue for computer operators and anyone driving at night. And off course, AR lenses enhance appearance by removing all distracting reflections. Special coatings have been developed to help protect lenses from normal scratching. The modest additional cost for such scratch coating is usually a prudent investment.