Scratch-Resistant Coating. No eyeglass lens material — not even glass — is scratch-proof. However, a lens that is treated front and back with a clear, hard coating does become more resistant to scratching, whether it's from dropping your glasses on the floor or occasionally cleaning them with a paper towel. Children's lenses, especially, benefit from a scratch-resistant hard coat.
Ultraviolet Treatment. Another lens treatment that is beneficial but invisible to the naked eye is ultraviolet (UV) protection. Just as we use sunscreen to keep the sun's UV rays from harming our skin, UV treatment in eyeglass lenses blocks those same rays from damaging our eyes. Overexposure to ultraviolet light is thought to be a cause of cataracts, retinal damage and other eye problems.
Anti-Reflective Coatings. To improve both the vision through the lenses and the appearance of the glasses, an anti-reflective coating (also called AR coating) is applied. AR coatings are similar to the coatings found on microscopes and camera lenses.
Each layer is scientifically calculated to block reflected light. The result is that you'll see a reduction in glare, annoying reflections and halos around lights. This is a great safety benefit when you're driving at night.
Also, anti-reflective coating reduces both internal and external reflections on the lenses themselves, creating a nicer cosmetic appearance. Internal reflections appear as rings that make lenses look thick. External reflections mask your eyes from a clear, complete view when someone is looking at you. So with an anti-reflective coating, eyeglass lenses appear thin or non-existent, and your eyes look more natural. If you have a strong prescription, you can use the AR coating in conjunction with high-index lenses to make your glasses look and feel as thin as possible.
Photochromic lenses. Often referred to by their trade names Transitions (polymer lenses) or photogrey (glass lenses). Made from either glass or plastic, these eyeglasses change from clear to tinted when exposed to sunlight. This eliminates the need for prescription sunglasses. These eyeglass lenses may not darken in a car because the windshield could block the ultraviolet rays from the sun.
Driving Lenses. A new category of lenses, DriveWear, Activated by Transitions, has stepped in with a unique, high tech solution for driving. DriveWear lenses combine the glare protection of polarized prescription sunglasses (see below) and photochromics (see above) which respond to both visible and UV light . The result is a lens that can sense the light coming in from outside of the car and transition to dark accordingly. Drivewear lenses are capable of sensing and reacting to varying light conditions both outside and behind the windshield of the car. From bright sunlight accompanied by intense, blinding glare, to overcast inclement conditions, Drivewear lenses provide the ideal visual solution.
Polarized sunglasses. Light reflected from water or a flat surface can cause unwanted glare. Polarized lenses reduce glare and are useful for sports and driving. These lenses may cause the liquid crystal displays on the dashboard of cars to appear invisible.
Mirror Coatings. In contrast to anti-reflective coatings, which are very clear, mirror coatings (also called flash coatings) are bold statements of color. Just as the name implies, a mirror coating is highly reflective. The mirrored sunglasses associated with state troopers are one example of a flash coating.
The technology has advanced, however, so that today's choices include colors of the rainbow as well as silver, gold and copper metallic mirror coatings. Hot pink, blue — almost any color is available.
Mirror coatings are purely cosmetic: the wearer perceives no difference in vision regardless of what color the coating is. Only those looking at the person wearing the glasses can see the color of the mirror coating. Mirror coatings are generally applied over sunglass-dark lenses. Obviously, a highly reflective flash coating prevents others from seeing the eyes of the wearer.
Ultraviolet Treatment. Another lens treatment that is beneficial but invisible to the naked eye is ultraviolet (UV) protection. Just as we use sunscreen to keep the sun's UV rays from harming our skin, UV treatment in eyeglass lenses blocks those same rays from damaging our eyes. Overexposure to ultraviolet light is thought to be a cause of cataracts, retinal damage and other eye problems.
Also, anti-reflective coating reduces both internal and external reflections on the lenses themselves, creating a nicer cosmetic appearance. Internal reflections appear as rings that make lenses look thick. External reflections mask your eyes from a clear, complete view when someone is looking at you. So with an anti-reflective coating, eyeglass lenses appear thin or non-existent, and your eyes look more natural. If you have a strong prescription, you can use the AR coating in conjunction with high-index lenses to make your glasses look and feel as thin as possible.
Photochromic lenses. Often referred to by their trade names Transitions (polymer lenses) or photogrey (glass lenses). Made from either glass or plastic, these eyeglasses change from clear to tinted when exposed to sunlight. This eliminates the need for prescription sunglasses. These eyeglass lenses may not darken in a car because the windshield could block the ultraviolet rays from the sun.
Polarized sunglasses. Light reflected from water or a flat surface can cause unwanted glare. Polarized lenses reduce glare and are useful for sports and driving. These lenses may cause the liquid crystal displays on the dashboard of cars to appear invisible.
Mirror coatings are purely cosmetic: the wearer perceives no difference in vision regardless of what color the coating is. Only those looking at the person wearing the glasses can see the color of the mirror coating. Mirror coatings are generally applied over sunglass-dark lenses. Obviously, a highly reflective flash coating prevents others from seeing the eyes of the wearer. 
