Material Specifications

One of the most important decisions you will make when setting up a prescription safety eyewear program is the choice of lens material. Safety lens choices have increased over the past few years and are offered in several materials: Polycarbonate, CR39 Plastic, High Index Plastic, Trivex and Glass.

Shannon Optical strongly recommends the use of Polycarbonate Lens Material.

Polycarbonate: Polycarbonate is the lens choice for maximum impact resistance. With the designation of High Impact, they are 10 times more impact resistant than conventional plastic or glass lenses. While impact resistance does not mean shatterproof, polycarbonate lenses provide an extra level of protection over other lens materials. Polycarbonate will also be thinner and lighter than glass or plastic lens materials and have UV Protection standard.

Trivex: Trivex lenses are composed of a newer plastic that has the same characteristics as polycarbonate lenses. Like the polycarbonate lenses, trivex lenses are thin, lightweight, and impact resistant. The difference between trivex and polycarbonate lenses is that trivex has better optical qualities and better corrects vision.

CR-39 Plastic: The first polymer lens perfected replaced the use of glass in most prescription eyewear due to its being lighter and less prone to shattering than glass. Plastic lenses provide a vision comparable to glass, and provide good scratch resistance. Plastic lenses can also be tinted to provide glare protection in certain situations.

High Index: This lens was designed for higher prescription ranges that polycarbonate was not well suited. It provided vision comparable to CR-39 Plastic as well provided a thinner lens for higher prescriptions.

Glass: For years, glass was the only lens material available. It offers superior optics, which makes it a good choice in non-impact situations. The most scratch resistant material, the primary disadvantage of glass is that is generally twice the weight of plastic or polycarbonate lenses. Due to the fact that glass lenses are tempered in a heated chemical bath to become safety rated, once in the field, stray grinding sparks or welding splash can lodge in the lens and break the temper, rendering the lens unsafe.