OP, I am also blind as a bat, so I know the feeling. I wear contacts most of the time, but if you will be wearing glasses when you are at MK, I would suggest taking them off when you ride SM. First of all, it's really dark anyway. More importantly though, if you do wear your glasses and lose them, and you are as blind as me, you can't just run to Lens Crafters (or any eyeglass store) and order glasses in an hour... my glasses are special order and take a couple of days because they have to shave them down so they fit into the frames and don't look like Coke bottles! And I know you wouldn't want to be without glasses in WDW for that long! If you really want to keep your glasses on, you should look into a strap that goes around your neck (as other posters have mentioned) or actually hold onto them with one hand (or two!) while you ride SM. Have fun!