FLS, glasses is a strange subject with these VR headsets. With both units, I've tried with and without glasses. I have become nearsighted in my old age now (42), and have about -1.5 in left and a slight astig and -1.3 in the right, so not terrible, but at night, noticeable. I tried both with glasses, without, and contacts. For me, I can get away without correction in VR, as I read without glasses fine, and even thought the some say the focus distance INSIDE vr requires correction for nearsightedness, this hasn't been my experience.
It's a very, very subjective matter, so try it out and see for yourself. Both headsets allow you to modify the width of the binocular lenses, spreading them apart or making them slower, and the Vive also allows you to make the lenses closer, or farther, for glasses use or long eyelashes, etc. The Rift has a method of doing this too, various foam width sets, and I've heard a mechanical system like Vive is coming in later Rift models. Rift has a slider for the width as well.
So, try it out, you'll find something that works, I gaurantee it, may be with or without glasses/contacts, but it'll work one way or t'other.