I rode FOP, Tough to be a Bug, Toy Story Mania, Philharmagic, Muppets 3D, all with my regular glasses underneath. No problems. The glasses all fit. I had also read the 3D glasses at FOP didn't fit kids, but I "bent" them in a little at the earpieces so the were snug on my 7 year old GS. I think most of them have a little give for adjustments, but I didn't need it for my regular glasses to fit fine underneath. I wear bifocals, and didn't notice any distortions, but I sat nearer the middle or back of the theater attractions.