[epaik]

From Carmack's post in the comments of the Kickstarter:

The early prototype could not be worn with glasses. If you modify it to stand off far enough from the face to allow glasses, the fov will be reduced a lot. One reason it can be so light is that it has smallish lenses very close to your eyes. With the limited resolution, you don't really need 20/20 effective vision. I hope someone experiments with the kits and builds a variable focus version, but the standard system is fixed focus.