Opticians have a great deal of control over the lens material. The choice of lens material is specific to each clients optical needs and possibly a combination of other requirements. Learn the basics:

CR-39 (Columbia Resin Formula 39): Basic plastic. This is ideal for simple prescriptions and provides good optics. Plastic is affordable and tints easily. 

Polycarbonate: Thinner than plastic and nearly unbreakable, polycarbonate is recommended for anyone engaged in physical activity or those who require safety glasses. For children this is a must!

Trivex: Military grade impact resistance that is equal to that of polycarbonate. Trivex offers superior optical clarity over polycarbonate, but tends to have the same thickness as CR39.

Glass: Glass offers the best optical clarity and is resistant to chemical abrasion. However, glass is the heaviest of all materials.

Hi-Index: For clients with corrective requirements above a +/- 4.00 diopters, Hi-Index will keep your lenses as thin as possible.

Anti-Reflective Coating (ARC): Of course, ARC is not a lens material. Rather, it's a coating that's applied to the lens. ARC maximizes the amount of light that passes through the lens and into your eye. It also eliminates back-reflections such as the white of your eye or lit objects behind you (such as lamps). The result is enhanced optical clarity and contrast. Cosmetically, ARC also helps people see your eyes behind the lens rather than reflections. ARC is highly recommended on all orders, and required on Hi-Index 1.74.