One reason I don't like to use my glasses is that they are plastic, and while they have a hard coating and non reflective (the best and very expensive), if there is a bit of dirt or anything on the eyepiece, it is possible, and I have done it, to scratch my glasses. Also, I find it harder to really get the framing I want so when I really get down to it I take off my glasses but again, I would like to get some with the flip up frames.