>>274415379
If you try to focus on anything that's virtually closer than than about 2 meters, your eyes will try to refocus closer, even though the screen of the headset is fixed 2 meters away (optically by the lenses). It's called the vergence accommodation conflict. If you play VR for long enough (about 2-3 hours for me) your brain will give up trying to refocus and things will stay sharp again, but then there's like an hour of recovery back in the real world before you relearn how to focus.