Cycling glasses life span

I've had my Tifosi sport glasses with photochromic lenses for about 4 years. Lately, when I rode them in 10 am morning sun, my eyebrow and eye started to feel terrible pain, that passed once I removed my sunglasses. A friend of mine, that works in a bike shop said that polycarbonate lenses have a life span of about 3 years. I've bought a new pair of glasses, but now I'm trying to decide what to do with the old pair. So the question, do polycarbonate lenses really degrade with wear, time and when wiping them?