Admittedly I'd not bought a new pair of glasses for about 8 years, one of my pairs have to be repaired all the time (with super glue) because they have a weakness on one side (they normally put a bigger screw in but couldn't) and the other pair used to wear uneven, one side was lower then the other thus I looked funny, I was wearing these today when the lens popped out somewhere, on the way home my eyesight seemed a bit off and it wasn't till I stopped until I realized the lens had gone. So now I am looking for a pair of glasses that will hold together under the forces exerted when putting them on inside a helmet, is it best to go with a thicker pair.