Lens coatings for glasses: So many choices!
Lens coatings can enhance the durability, performance and appearance of your spectacle lenses. This is true whether you wear single vision, bifocal or progressive lenses.
If you are thinking about purchasing new glasses, here are lens coatings and treatments you should consider.
Anti-reflective coating (also called AR coating or anti-glare coating) is a microscopically thin multilayer coating that eliminates reflections from the front and back surface of spectacle lenses.
By doing so, an AR coating makes your lenses nearly invisible so people can focus on your eyes, not distracting reflections from your spectacles.
Anti-reflective coating also eliminates glare caused by light reflecting from your lenses. With reflections eliminated, lenses with an AR coating provide better vision for night driving and more comfortable vision for reading and computer use.
An AR coating is highly recommended for all spectacle lenses, but particularly for polycarbonate and high-index lenses, which reflect more light than regular glass or plastic lenses if anti-reflective coating is not applied.
Also, aspheric lenses, which have flatter curves than regular lenses, often cause more noticeable reflections, so an AR coating is highly recommended for these lenses, too. Additionally, an AR coating is beneficial when applied to the back surface of sunglasses to eliminate "bounce-back" reflections when you are facing away from the sun.
For the best possible comfort in all lighting conditions, opticians usually recommend applying an anti-reflective coating to photochromic lenses. AR coatings improve light transmission through the lenses for night driving and helps photochromic lenses reduce glare in bright sunlight.
[Read more about anti-reflective coating.]
No spectacle 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 from dropping your glasses on the floor or occasionally cleaning them with a paper towel.
Childrens' lenses, especially, benefit from a scratch-resistant hard coat for greater durability.
Today, most spectacle lenses, including high-index lenses and lenses made of polycarbonate and Trivex, have a built-in scratch-resistant coating.
Since scratch-resistant coatings are sometimes optional, make sure your optician knows that you want your spectacle lenses to include hard coating for extra durability. Also, ask about the warranty on spectacle lenses that are treated with scratch-resistant coating versus those without the coating.
Keep in mind that even the best scratch-resistant coating can't completely protect your lenses from wear and tear. To keep your glasses looking new, store them in a cushioned case when not in use, and clean your lenses with a microfibre cloth and the cleaning solution your optician recommends.
Also, be wary of products that promise to repair 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.
If you live in a cold climate, nothing is more frustrating than having your spectacles fog up when you come in from the cold. This also can be a safety issue, since it limits your ability to see until the fog clears.
Lens fogging can be especially dangerous for police officers and other first responders to emergency situations.
Lens fogging is caused by tiny water droplets that form by condensation on the surface of spectacle lenses when the lenses are significantly cooler than the surrounding air temperature.
A number of companies make anti-fog sprays and coatings designed to reduce the condensation of moisture on lenses that causes fogging. So, your lenses and vision stay clear when you make the transition from a cold environment to a warm one.
Anti-fog coating also may keep your lenses from fogging up during sports and other times when you are hot and perspiring.
Anti-fog coatings can be applied to plastic, polycarbonate and other spectacle lenses, including high-index lenses and Transitions photochromic lenses. The coating is applied to the lenses before they are cut to fit into your frame at the optical lab. Ask your optician about pricing and availability.
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 spectacle 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 spectacle lenses block most UV light, but adding a UV-blocking dye boosts UV protection to 100 percent for added safety. Other spectacle 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.