Plastic CR-39 Lenses
Plastic CR-39 Lenses commonly referred to as "Plastic Lenses" is the most basic lenses for prescription glasses. Invented in 1940 by Columbia Resin, it got its name because it was the 39th formulation for the Columbia Resin company. CR-39 replaced glasses lenses and was a staple in the eyeglass lens industry for years. CR-39 has an index of refraction of 1.58 and is good for the most basic of prescriptions. CR-39 lens material is available with scratch resistant coating and anti-reflective coating and UV filters can be applied to them. Since these lenses are more brittle than other lens materials it is not recommended for rimless, semi-rimless and drill mount eyeglass frames.