In the past, eyeglass lenses were made exclusively of glass. Today, most eyeglasses are made of high-tech plastics. These new lenses are lighter, do not break as easily as glass lenses, and can be treated with a filter to shield your eyes from damaging ultraviolet light. Go to our What Lenses Should I Buy page for advice on which lens to purchase.
Plastic (CR-39) Lenses. Most people refer to this lens type as "Regular" or "Plastic" Lenses. The patent of CR-39 allyl diglycol carbonatemonomer in 1945 marked a key milestone in the history of the optical industry.
Plastic (CR-39) lenses combine the optics of glass with the excellent mechanical, thermal and chemical resistance properties of a thermoset material. Although, polcarbonate lenses are replacing plastic (CR-39) lenses as the industry standard.
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. Plastic lenses are great for prescription sunglasses due to their tintability factor as you can virtually tint a plastic lens to any color under the rainbow.
Polycarbonate Lenses. These eyeglass lenses are impact-resistant and are a good choice for people who regularly participate in sporting activities, work in a job environment in which their eyeglasses may be easily scratched or broken, and for children who may easily drop and scratch their eyeglasses. Polycarbonate lenses also provide ultraviolet protection.
Trivex Lenses. Made from a newer plastic with similar characteristics of polycarbonate lenses. It is lightweight, thin and impact-resistant and may result in better vision correction than the polycarbonate lenses in some people.
High-Index Plastic Lenses. Designed for people who require strong prescriptions, these eyeglass lenses are lighter and thinner than the standard, thick "coke bottle" lenses that may otherwise be needed.
Aspheric Lenses. These eyeglass lenses are unlike typical lenses, which are spherical in shape. Aspheric lenses are made up of differing degrees of curvature over its surface, which allows the lens to be thinner and flatter than other lenses. This also creates an eyeglass lens with a much larger usable portion than the standard lens.
In the past, eyeglass lenses were made exclusively of glass. Today, most eyeglasses are made of high-tech plastics. These new lenses are lighter, do not break as easily as glass lenses, and can be treated with a filter to shield your eyes from damaging ultraviolet light. Go to our 
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. Plastic lenses are great for prescription sunglasses due to their tintability factor as you can virtually tint a plastic lens to any color under the rainbow.
