When I was a kid I played outside in the full sunlight all the time and never had sunglasses, but nowadays if I go outside and it's full sunny I need sunglasses. What happened?
Is it my eyes aging? (My acuity of vision is still as good as it ever was, though I realize that might not be measuring the same thing.) Is it that I live in a more northerly attitude so the sun is lower in the sky? Is it the thinning of the ozone layer and other environmental depredations making sunlight more intense? Did I always need sunglasses and just didn't know it, or got used to it?