I always use prescription glasses, and have been saved many times by them, not only in the field, also in the operating room!!!
For big game hunting and rifle shooting I use my regular prescription glasses. For upland game hunting and while using the shotgun I use specially designed shooting glasses. I used to shoot IPSC pistol competition, and wearing protection glasses was obligatory, which was a good way of getting used to shoot all the time with glasses.
It is better to prevent than to say should have done it!!!