Anti-reflective coating (also called AR coating or anti-glare coating) improves both your vision through your lenses and the appearance of your eyeglasses.
Both benefits are due to AR coating's ability to eliminate reflections of light from the front and back surface of eyeglass lenses.
AR coating is especially beneficial when used on high-index lenses, which reflect more light than regular plastic lenses. Generally, the higher the index of refraction of the lens material, the more light that will be reflected from the surface of the lenses.
For example, regular plastic lenses reflect roughly 8 percent of light hitting the lenses, so only 92 percent of available light enters the eye for vision. High index plastic lenses can reflect up to 50 percent more light than regular plastic lenses (approximately 12 percent of available light), so even less light is available to the eye for vision. This can be particularly troublesome in low-light conditions, such as when driving at night.
Today's modern anti-reflective coatings can virtually eliminate the reflection of light from eyeglass lenses, allowing 99.5 percent of available light to pass through the lenses and enter the eye for good vision.
Anti-reflective coating reduces the glare that you see, as well as the glare that others can see on your lenses.
By eliminating reflections, AR coating also makes your eyeglass lenses look nearly invisible so people can see your eyes and facial expressions more clearly. Anti-reflective glasses also are more attractive, so you can look your best in all lighting conditions.
The visual benefits of lenses with anti-reflective coating include sharper vision with less glare when driving at night and greater comfort during prolonged computer use (compared with wearing eyeglass lenses without AR coating).
Anti-reflective coating also is a good idea for sunglasses, because it eliminates glare from sunlight reflecting into your eyes from the back surface of tinted lenses when the sun is behind you. (Generally, AR coating is applied only to the back surface of sunglass lenses because there are no cosmetic or visual benefits to eliminating reflections from the front surface of dark-tinted lenses.)
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.
Some eyeglass lenses have factory-applied AR coating on both lens surfaces. Other lenses, particularly progressive lenses and other multifocal lenses (i.e., bifocals and trifocals), have the coating applied after the lenses have been customized to your eyeglass prescription by an optical lab.