There was a segment on the local news here a year ago about what glasses were best. It was a consumer awareness thing they have every so often and what they found, or said they found was that the cheap sunglasses you get at the gas station were just as effective as high dollar glasses at filtering UV rays. I have to use the lightest tint I can because I can't distinguish color very well with those dark glasses. I've lost orientation several times with a dark pair and replaced them with a lighter pair.