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.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.
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.
Source:http://www.allaboutvision.com/lenses/anti-reflective.htm