CR-39 (regular plastic) Lenses
“Regular plastic” eyeglass lenses refers to what is known in the industry as “CR-39 plastic” lenses. Regular plastic lenses have better visual clarity than the thinner polycarbonate or high index lenses, and they are less expensive. For low prescriptions, regular plastic lenses are usually the best choice for prescription lens material. However, regular plastic prescription lenses also have some drawbacks and limitations in certain situations. For example, if your prescription is higher than +/-3.00, the regular plastic lens will become thicker and heavier, and you could benefit from moving to a polycarbonate or high index lens. Also, if you have a three piece rimless eyeglass frame, you should not use a regular plastic lens because it is likely to crack under the strain. Finally, children and sporting adults are recommended for polycarbonate or high index lenses because they offer better eye protection than regular plastic lenses.
If your prescription is higher than the +/-3.00, you may want to look at a higher index (and more expensive), thinner and lighter lens. CR-39 is the standard type of plastic used for everyday use, around the office, or for shopping. These lenses have the least distortion of any non-glass lens. For children or active adults engaged in sporting activities, we strongly recommend polycarbonate (impact resistant) lenses. If the sphere on your prescription is +/-2.00 or lower, you will not benefit from the more expensive thin high index lens types. If the sphere on your prescription is higher than +/-2.00, you will benefit from the selection of a "thin" lens type. If the sphere on your prescription is higher than +/-3.00, we recommend a 'thin' lens type. Thinner lenses have three advantages: they do not look 'thick', they do not magnify or minify your eyes when seen by others, and they are lighter.