I have a pair of Ray-Ban polarized sunglasses (so not some cheap drugstore sunglasses, and they are made in Italy not China) that I got two years ago. I just got back from a vacation, and I noticed that one of the lenses has some sort of damage along the bottom:

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On the inside of the lens, you can see some of the coating has started to come off:

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What happened? I never dropped them. When they're not on my face or hanging from my shirt collar, I always put them inside a hard case. I never leave them sitting unprotected in a car. If I ever leave them in a car, it will be for less than an hour, and they will be inside of the case inside of my backpack. Sometimes I will clean them using Zeiss lens wipes. Also, I don't wear them every day - I only wear them on trips, so they have not been subject to excessive wear.

I have heard of something called "crazing" that can affect lenses that are subject to excessive heat - could that be what happened here? The only other thing I can think of is sweat, but I don't know if perspiration can damage lenses.

  • 2
    Bad coating process. Starting to peel... – Jon Custer Aug 18 '19 at 22:47
  • Sunscreen has, in my experience, caused similar damage, and it can easily move from your face to the lenses. – jhch Aug 19 '19 at 14:29
  • @JohnHughes Oh that's another possibility I didn't think of, as well as picaridin insect repellent lotion. – pacoverflow Aug 19 '19 at 15:08
  • The problem with glass lenses is that you can't sandwich the polarizing film between two outer layers like they do with polycarbonate lenses. The film is exposed to damage. In this case it doesn't look like delamination (it wouldn't happen anyway since Ray-Bans are mostly glass and not laminates). It looks more like it's a chemical attacking either the film or the bonding agent from the edge inwards. – Gabriel C. Aug 19 '19 at 15:25
  • DEET insect repellent is well-known to dissolve or soften many plastics; picaridin could have a similar effect. – aucuparia Aug 20 '19 at 9:14

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