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Plastic Lenses Material (CR-39) ( Helpful:0 ) Back »

*Refractive index (nd): 1.498 (standard)
*Abbe value (Vd): 59.3
*Density: 1.31 g/cm³
*UV cutoff: 355 nm


The lens is light weight compared to glass, and may be made in just about any prescription, though many people with higher prescriptions prefer to use Hi-Index Lenses. The higher the index, the thinner the lenses. Plastic lenses are great for prescription sunglasses due to their tintability factor and you can virtually tint a plastic lens to any color under the rainbow.


Developed by PPG during WWII, CR-39, also known as plastic or hard resin, serves as a much lighter lens material (approximately 50% lighter) than glass. CR-39, however, is far less scratch resistant and often must be coated to improve its scratch resistant characteristics.



Lighter than glass
Readily tintable
Less likely to fog



Susceptible to scratching (correctable by coating)
Lower index of refraction makes it less suitable for higher powered prescriptions

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