February 6, 20153 found this helpful
I want to know who, when buying an anti-reflective coating, if any of you were ever told that heat will destroy an anti-reflective coating? By using a hair dryer, burning a fire in the back yard, cooking where an amount of heat is dispensed when opening an oven or grill. Leaving glasses in the car, etc, etc, etc.
I was at an optical place, not where I bought my glasses, when they had asked if I wanted my glasses adjusted? I thought Oh how nice of them. In doing so, they fried (spidered) the AR coating. I went to Sam's where I had purchased them, to let them know what happened and they acted like it was common knowledge about the heat issue. I was told "Oh, yes, a hair dryer will do that" I asked where that was in my written warranty? (there wasn't a warranty given) Sam's did replace the lenses, but according to them, "we are done". So I spent $544. on a pair of high index lenses that were destroyed in three months by a professional, You get a better warranty on a 30 dollar toaster.
The point, they sell the anti-reflective coating as though it is a cosmetic add on. But in reality there is an important reason for having the anti reflective coating. First, understand that I wear -9.25 and -11.25 diopter progressive high index lenses. That's very very nearsighted. the edge of my glasses are approx 1/2" thick at the edge. An anti-reflective coating will eliminate the internal reflection of light on the outside and the inside of the lens.
A lens has four surfaces. the outside of the front, and the outside of the back of the lens. but the other two surfaces are on the inside of the lens. The inside of the lens, on the back of the front surface and the other is the front inside surface of the back of the lens.
The lenses have reflectence off all four surfaces. Ex. if you stand in front of a mirror and there is an identical mirror behind you (the reflective coating of the mirrors are facing each other) and you look ahead into the mirror, the reflection will look as though there are several mirrors in play. The same thing happens inside an optical lens. The higher the - diopter or the more nearsighted you are, the more importance of having an anti reflective coating. (it eliminates the coke-bottle effect that you see with glasses without the coating, unless you are far sighted and that's another ball game).
The major problem that I see, is that the higher the diopter, or the higher the refractive index (oops New term, refractive index- you know when you put a straw into a glass of water, or a stick into water and the stick or straw appears to bend? that appearance of the stick or straw bending is the refractive property of the water. Hence, lenses have a refractive index to them.
The higher the Refractive index the more the light bends to achieve, hopefully for a proper correction for you to see. The lenses are denoted by this number= Index of refraction. Mine are in a 1.67 index of refraction lens. I would have preferred it to have been in a 1.74.) , the need for the anti-reflective coating becomes more important to have. Not as a cosmetic ad on, but for providing a more effective lens.
We are being sold a bill of goods, that is loop- holed as a cosmetic option, where in reality it is a medical necessity. And apparently it is not for the seller of the glasses to inform you of the life style change that is going to be required of you if you want your anti-reflective coating to last for the duration of the glasses, Not the life of the prescription, but the life of the glasses. When I pay 800 dollars for glasses, they better last me 10 years. but, if you use a hair dryer, oops, too bad here go spend another 800 dollars for glasses. Not there fault.
As a tax payer, we spend millions of dollars, through educationally funded research, missile defence, Nasa, etc for optic research for the aforementioned but also for the preservation of sight and better seeing capabilities. Why can I not get the anti -reflective coating through the research performed in order to come up with the hubble telescope anti-reflective coating, or the anti-scratch that is on the scanner glass at the super market. Why are we sold inferior products for that which is a medical device and not cosmetic option/ We deserve better. We need to demand better!