What is the difference between anti-glare and anti-reflective coating for glasses? Which one is better for a person using the computer for greater than 8 hours a day?

You’ve probably heard of an anti-glare or an anti-reflective glare coating for your new glasses. At most optical offices they can cost anywhere from $20 to $200. So what are they? Does it make a difference in your vision? Are all coatings created equal?

Anti-relfective or anti-glare coating (I will refer to them as AR coatings from here on out) is a special coating that can be applied to the front or back or both sides of a lens to help reduce the reflections of the light in your lenses and to allow for the highest amount of “good” light to enter your eye so that theoretically you can get the clearest, most natural looking vision possible. To understand what they do you need to understand how we see, and what causes glare and reflections in lenses.

When we look at an object what we are really seeing is the light that is reflected off of that object, which is why we can’t see in the absence of light, i.e. in a dark room. The light enters your eye through the cornea and hits a specific spot on the back of your eye – the retina. If you have a refractive error and need glasses it is simply because the light is not hitting your retina. Your eye may be too long – myopia, the eye may be too short – hyperopia, or your cornea is not in the correct shape – astigmatism. There are other issues like cataracts, glaucoma, diabetes etc. but for the point of this article we’re just talking about those three refractive errors. When you wear glasses, the lenses are bending the light so that it lands right on the retina and you can see clearly.

But some of the light that hits the lenses naturally is reflected off the lens causing a glare on that spot (figure 1). Kind of like looking at a metal object that is in direct light, you will see glare where the light is reflecting off of it. You probably notice this especially at night as little starbursts around the headlights of on-coming cars or even the street lamps. Another issue with lenses is some of the light that goes through the lenses is reflected by the BACK of the lens as well, which can disperse though the lens, again causing glare (figure 2). The light may even reflect back to the front of the lens and then back again causing a “ghost” image on the lens where it looks like there two objects instead of one (figure 3). All of this glare causes blurriness in your vision making it difficult to see clearly and tires your eyes out as they try to filter out the “noise” from the reflections and the glare.

So how does the coating work? To put it simply it either absorbs the reflected light so that you don’t see it and/or bends the light so that it “crashes” into its reflection canceling it through destructive interference. This minimizes, and in many, cases gets rid of glare all together. Does it really make a difference? You bet. Not only do you see better through the lenses but people can actually see your eyes in the lenses without seeing glare or their own reflection. It’s not 100% perfect but the technology is always improving. People who have astigmatism, high prescriptions, are on the computer a lot, or who work in bright offices benefit the most from AR on their lenses.

So what are the cons of having AR coatings on your lenses? Well because the lenses are so clear, any smudges or dirt that you get on the lenses is going to show up like a neon sign. They are not dirtier than a pair without AR but they are more obvious because you don’t have the glare and distractions that would usually hide it. You will find that you are cleaning your lenses more often because of it. Also since it is a coating that is usually applied to the outside of the lenses it can scratch, peel, or wear off. So unless your 6 year old has a specific need where he would benefit from the AR coating and is responsible enough to take care of them, then I would probably say wait a few years. Which brings us to our next point: Not all AR coatings are created equal. There are some AR coatings that you could put your 6 year old in without the issues normally associated with AR, but it’s going to cost a little more. In almost all cases you will get what you pay for.

There are many different types of AR coatings and a lot of optical offices have their own proprietary AR coating, so it’s hard to just give a list of what coatings to avoid and which ones are good. Usually you want to stay away from “standard AR” coatings as they are generally the thinnest possible coating that is just sprayed on to the lens and is not very durable. You want an AR coating that has at least a scratch coating on top of it to help with durability and a hydrophobic coating as well which will help repel dust, water and oils on the lenses. Ask your optical about how their AR coatings are made. Now one of the best AR treatments (it’s considered a treatment because it is bonded on a molecular level to the whole lens and not slapped or sprayed on) out there are the Crizal brand AR. They spend millions of dollars on research and are the industry leaders in AR. They have a few different types; from good to best: Crizal easy, Alizé, Avancé, and their latest and greatest: Sapphire. They also have a Crizal SunShield that goes on polarized glasses which is an AR coating that absobs instead of reflecting UV radiation into the eye when put on the back of sunglasses. All of their ARs are designed to get rid of the 5 “enemies” of clear vision: glare, scratches, dust, water, and smudges. And they all do a really good job, with each one being substantially better than the last. Below is a embedded you tube video of what the lenses do from the official Crizal website.