Eyeglass Lens Coatings:
Anti-Reflective, Scratch-Resistant,
Anti-Fog and UV

By Liz DeFranco, ABOC, NCLC,
with contributions by Gary Heiting, OD

Lens coatings can enhance the performance and appearance of your eyeglass lenses. If you are thinking about purchasing new eyeglasses, here are lens coatings and treatments you should consider.

Anti-Reflective Coating

Anti-reflective coating (also called AR coating or anti-glare coating) improves both your vision through your lenses and the appearance of your glasses.

AR coatings are similar to the coatings found on microscopes and camera lenses. They consist of several layers of metal oxides applied to the front and back lens surfaces. Because of the layering effect, AR coatings sometimes have a hint of green or purple color, depending on the individual manufacturer's formula.

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, reflections are eliminated and eyeglass lenses look thinner or non-existent, and your eyes are more visible so you can make better eye contact with others.

Anti-reflective coating benefits virtually everyone who wears eyeglasses. Also, research shows wearing AR coated lenses improves night driving vision and increases comfort during prolonged computer use (compared with wearing uncoated lenses).

AR coating is especially beneficial if you choose high-index lenses. These thinner, lighter lenses reflect more light than regular plastic lenses unless anti-reflective coating is applied.

Anti-reflective coating is also beneficial when applied to the back surface of lenses in sunglasses, because it eliminates reflections of sunlight into your eyes from the lenses when the sun is behind you. (Since the purpose of sunglasses is to reduce how much light enters your eyes and because you aren't concerned about making eye contact with others when wearing shades, there is no benefit to having AR coating applied to the front surface of sunglass lenses.)

Anti-reflective coating reduces the glare that you see, as well as the glare that others can see on your lenses. An anti-scratch coating can lengthen the life of your lenses, while hydrophobic coatings keep rain, snow and fog at bay.

Most premium anti-reflective coatings include a "hydrophobic" surface layer that prevents water spots from forming and makes the lenses easier to clean. Some AR coatings also include an "oleophobic" surface layer that repels skin oils and makes it easier to remove smudges from the lenses.

When cleaning AR-coated lenses, use only products that your optician recommends. Lens cleaners with harsh chemicals may damage the anti-reflective coating.

Also, don't ever attempt to clean AR-coated lenses without wetting them first. Using a dry cloth on a dry lens can cause lens scratches. And because anti-reflective coating eliminates light reflections that can mask lens surface defects, fine scratches will be more visible on AR-coated lenses than on uncoated lenses.

Scratch-Resistant Coating

No eyeglass lenses — not even glass lenses — are scratch-proof. However, lenses that are treated front and back with a clear, scratch-resistant coating have a much harder surface that is more resistant to scratching, whether it's from dropping your glasses on the floor or occasionally cleaning them with a paper towel. Kids' lenses, especially, benefit from a scratch-resistant hard coat.

Today, most eyeglass lenses, including high-index lenses and lenses made of polycarbonate and traditional plastic materials, have a built-in scratch-resistant coating. Since scratch-resistant coatings are sometimes optional, make sure your optician knows that you want your eyeglass lenses to include hard coating for extra durability. Also, ask about the warranty on eyeglass lenses that are treated with scratch-resistant coating versus those without the coating.

Since a scratch-resistant coating can't completely protect your lenses from wear and tear, do keep your glasses in a cushioned case, and clean them with a microfiber cloth and the cleaning solution your optician recommends.

Also, be wary of products that promise to repair your scratched lenses. These products may fill in the scratches, but it is impossible for them to make the scratches disappear so the lenses look new again.

Anti-Fog Coating

If you live in a cold climate, nothing is more frustrating than having your eyeglasses fog up when you come in from the cold. This also can be a safety issue, since it limits your ability to see for several minutes until the fog clears. Lens fogging can be especially dangerous for police officers and other first responders to emergency situations.

At least one eyeglass lens coating company (Opticote, Inc., Franklin Park, Ill.) has created a coating designed to eliminate this problem. Its thermally cured coating — called Fog Free — eliminates the condensation of moisture on lenses that causes fogging, keeping your lenses and vision clear when you make the transition from a cold environment to a warm one. It may also keep your lenses from fogging up during sports and other times you are hot and perspiring.

Fog Free can be applied to plastic, polycarbonate and other eyeglass lenses, including high-index lenses and Transitions photochromic lenses. The anti-fog coating is applied to the lenses before they are cut to fit into your frame at the optical lab. Ask your optical retailer about pricing and availability.

Ultraviolet Treatment

Another beneficial lens treatment is an invisible dye that blocks ultraviolet (UV) light. Just as sunscreen keeps the sun's UV rays from harming your skin, UV-protective treatments for eyeglass lenses block those same rays from damaging your eyes. Overexposure to ultraviolet light is thought to be a cause of cataracts, retinal damage and other eye problems.

Regular plastic eyeglass lenses block most UV light, but adding a UV-blocking dye boosts UV protection to 100 percent for added safety. Other eyeglass lens materials, including polycarbonate and most high-index plastics, have 100 percent UV protection built-in, so an extra lens treatment is not required for these lenses.

Photochromic lenses also block 100 percent of the sun's UV rays without the need for an added UV lens treatment.

[Page updated December 2009]