The material from which a lens is made has little impact on the corrective power of the lens, but it can have a major impact on lifestyle. Learn about the different lens material options and make the best choice for your next pair of eyeglasses.
Lens Materials
Polycarbonate lenses are made of a type of plastic that is more impact-resistant than standard plastic lenses. Polycarbonate lenses are also much thinner and lighter in weight. They are considered a high index plastic. Polycarbonate lenses also have built-in ultraviolet protection. Because of these properties, it is the lens material of choice for children’s lenses, sports lenses, and safety lenses.
Trivex is a relatively new material that is similar to polycarbonate lenses but with higher quality optics, and thus provides a clearer vision. Trivex is lighter in weight than standard plastic but not quite as thin as polycarbonate. Trivex is a more rigid material, making it a better selection for rimless or drill mount frames, and is just as impact resistant as polycarbonate.
Aspheric lens design gives several advantages to eyeglass lenses. An aspheric lens has flatter peripheral curvatures than a regular spherical lens. This reduces the amount a lens may bulge out of an eyeglass frame, reducing magnification of the eyes, which improves cosmetic appearance. Flatter peripheral curves also reduce distortions that occur when looking away from the center of the lens, making vision much crisper. Aspheric lenses are also much lighter in weight than standard spherical lenses.
Trivex is a relatively new material that is similar to polycarbonate lenses but with higher quality optics, and thus provides a clearer vision. Trivex is lighter in weight than standard plastic but not quite as thin as polycarbonate. Trivex is a more rigid material, making it a better selection for rimless or drill mount frames, and is just as impact resistant as polycarbonate.
Aspheric lens design gives several advantages to eyeglass lenses. An aspheric lens has flatter peripheral curvatures than a regular spherical lens. This reduces the amount a lens may bulge out of an eyeglass frame, reducing magnification of the eyes, which improves cosmetic appearance. Flatter peripheral curves also reduce distortions that occur when looking away from the center of the lens, making vision much crisper. Aspheric lenses are also much lighter in weight than standard spherical lenses.
Lens Treatments
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EyeGlass Guide and Photochromatic Demonstration
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Anti-reflective coating is applied to eyeglass lenses to reduce the amount of internal and external reflections. This increases the amount of light transmitted through the lens, which improves the quality of vision. The anti-reflective coating also decreases unwanted glare and halos at nighttime. It also makes the lenses appear somewhat invisible and very thin. While everyone could benefit from an anti-reflective coating, it is especially beneficial for people with high prescriptions, people who have a decrease in the vision at night, and professions in which cosmetic appearance is important. Scratch-resistant coatings are applied to the back and front of lenses in the manufacturing process. Although it is important to realize that no lens is scratch-proof, this special coating does make lenses harder to scratch when dropped or rubbed against a hard surface. Polarized lenses are usually used to make sunglasses. They are available most commonly in grey or brown tint but many other colors are available. Vertically polarized lenses decrease bright glare and reflections by blocking horizontal polarized reflected light. Polarized lenses have been used by fishermen for years to better deal with a bright light being reflected off the water and to see deeper into the water. Photochromatic lenses have a special chemical coating that makes them change to a dark tint in the sunlight and turn clear indoors. Photochromatic lenses are great for people who do not wish to carry a separate pair of prescription sunglasses.It is important to note that photochromatic lenses will not change behind the windshield of a car—the windshield prevents most of the UV light from reaching the lens. |