Thin Lenses

High-index
Aspheric
Polycarbonate

High-index = Lenses that are thinner & lighter in weight because the material is denser.

Standard plastic (Cr-39) is the material of choice with low to moderately strong prescriptions. It is relatively inexpensive, lighter than glass and scratch resistant. From moderately strong to severe, different "high-index" materials are called for. The term "high-index" refers to any lens material with an index of refraction greater than the 1.49 of Cr-39.

All lens materials being denser than air have higher refractive indices ranging from the 1.49 of CR-39 through 1.60 through 166/7 to finally 1.71, corresponding to progressively denser and thinner high-index lenses. 1.60 lenses are about 30-35% thinner than CR-39, and 1.66 lenses are about 40-50% thinner.

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