Anses and make your glasses look and feel as thin as possible. Sunglass lenses are best having AR coatings applied only to the back surface of the lens (which is the surface nearest the eye). Lenses in sunglasses are dark and light doesn't penetrate the lens surface. This effect causes the lenses to be highly reflective and prevents the AR coating from being as affective. A backside AR coating helps reduce reflections of light that enter from behind you and bounce off the surface into your eyes. A glare reducing backside coated lens is much more comfortable than a sunglass lens left uncoated.