>Lifetime of 2 to 3 years, daily use ... It seems to me like a short expected lifespan, following is anecdata. The glasses I am wearing (the frame) are/is 36

>Lifetime of 2 to 3 years, daily use ... It seems to me like a short expected lifespan, following is anecdata. The glasses I am wearing (the frame) are/is 36 or 37 years old. Every several years I had new lenses fitted to them, mostly because my eyesight slightly changed, right now they sport a brand new set of lenses because I broke one lens and since I use the photochromatic kind I couldn't have only the broken one replaced (the colour and capability to darken changes a bit over the years), but I don't think I replaced the lenses more than 4 times in these almost 40 years. Then I have another four pairs, one spare in the car glove compartment, one spare always in my suitcase, one for the motorbyke (sun lenses + short stems to fit under the helmet) and one as spare-spare. And I believe that (besides changing some lenses as well) none of these latter frames are more recent than 15 or possibly 20 years.