Advanced optical design technology allows aspheric eyeglass lenses to be made with flatter curves than conventional lenses, giving them a slimmer, more attractive profile. Conventional lenses have a front surface that is spherical, meaning it has the same curve across its entire surface, much like a baseball.
High-index eyeglass lenses are the right choice if you want thinner, lighter lenses and eyeglasses that are as attractive and comfortable as possible. Thinner, lighter high-index lenses are especially recommended if you have a strong eyeglass prescription for nearsightedness, farsightedness or astigmatism.
Photochromic lenses are optical lenses that darken on exposure to specific types of light of sufficient intensity, most commonly ultraviolet (UV) radiation. In the absence of activating light the lenses return to their clear state. Photochromic lenses may be made of glass, polycarbonate, or another plastic.
When wearing sunglasses without polarization, the lenses only reduce the amount of light that is transmitted through the lens both horizontally and vertically. If you choose polarized lenses, though, the glasses absorb horizontal light waves, while still allowing vertical waves to pass through.
Eyeglass lenses made of polycarbonate were introduced in the early 1980s in response to a demand for lightweight, impact-resistant lenses. Lightweight, impact-resistant polycarbonate and Trivex lenses are the best choice for safety glasses, sports eyeglasses and children's eyewear.
Lightweight, impact-resistant polycarbonate and Trivex lenses are the best choice for safety glasses, sports eyeglasses and children's eyewear. Since then, polycarbonate lenses have become the standard for safety glasses, sports goggles and children's eyewear.