Eyeglass Lens Coatings
An antireflective or anti-reflection (AR) coating is a type of optical coating applied to the surface of lenses and other optical devices to reduce reflection. This improves the efficiency of the system since less light is lost. The primary benefit is the elimination of the reflection itself, such a coating on eyeglass lenses makes the eyes of the wearer more visible to others.
A common problem with prescription glasses and sunglasses is called back-glare. This is light that hits the back of the lenses and bounces into the eyes. The purpose of an anti-reflective (AR) coating is to reduce these reflections off the lenses. In bad cases, you can actually see the reflection of your eye in the lens. Similar to a scratch-resistant coating, AR is made of a very hard thin film that is layered on the lens. It is made of material that has an index of refraction that is somewhere between air and glass. This causes the intensity of the light reflected from the inner surface and the light reflected from the outer surface of the film to be nearly equal. When applied in a thickness of about a quarter of light’s wavelength, the two reflections from each side of the film basically cancel each other out through destructive interference, minimizing the glare you see. AR coatings are also applied to the front of prescription eyewear and some sunglasses to eliminate the “hot spot” glare that reflects off the lens.
Not just for sun worshipers anymore! It is now commonly accepted medical fact that Ultra Violet rays cause a variety of eye diseases and disorders including corneal damage and cataracts for sunglass wearers or anyone who’s eyes are exposed for prolonged periods to the outdoors, UV protection is a must. Studies have shown that wearing sunglasses not treated with proper UV protection can actually be more harmful than not wearing glasses at all, because the darkness enlarges the pupil and allows more harmful UV rays to pass through the eye. This treatment also helps reduce discomfort from the glare from fluorescent lights and computer terminals. Proper Ultra Violet Treatment blocks out 100% of harmful Ultra Violet rays.