From what I've heard, keep in mind I have a bad memory and am not an expert, your eyes are supposed to work just as much if not more than while using a regular screen. You will focus your eyes all over, while on a 2d screen, you keep your eyes on the same position (center of screen, 20 inch away) for the duration of your gameplay.
And once you hit my age, your have have stopped accommodating for quite a while. I also wear glasses with two quite different prescriptions. I wonder how many of the VR systems will work for me.