None of the three people who are involved in the NH3 application are wearing glasses but I have looked into it a little. I think glasses would work fine (I believe I could wear my sunglasses while wearing the mask) except for the fact that the earpiece on the glasses would compromise the seal around your face.

Therefore, in order to wear this if you need glasses, I'm sure you would want to get the spectacle kit from 3M as well. I'm not sure how much that costs or how annoying it is to use as I have not looked into it much.