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Ignore the die, that's just to tilt the glasses up to more easily see the nose bridge. The rigup totally works, except that over time sweat degrades the heatshrink and it starts to swell. When the rigup was fresh, it was so streamlined that it almost looked factory made, but alas heatshrink doesn't like sweat and body oils.
The exact model is apparently M•Flex ME507. The frames would otherwise be really nice, if it wasn't for the fact that this is the second same set of frames I've had break in exactly the same way.
Sweat shouldn't attack plastic lenses. But one particular random chemical often does: acetone. It can strip coatings and turn tenses hazy. Did you use acetone by any chance?
I often use acetone to chemically-polish PLA parts. Whenever I do, I crack out the safety glasses. At the price I paid my lenses, I don't want to risk a splash - or possibly acetone fumes even - damaging them.
Trust me, sweat totally attacks the coating. The worst spots for me are always where my glasses tend to rub against my eyebrows.
Could be simple abrasion.
But yeah, lenses aren't eternal. You can make them last longer but they'll age and wear out ultimately. Entropy is a bitch 🙂