Yikes! You got problems during or after being in VR? You need to do Speed Reader's eye exercises! Check 'em out:
I do them every day!
I had discomfort after about 15 minutes..
Ignored it, then after about 30 minutes.. I just couldn't take it no more, it was this dull pain in the back of my eyes..
This is actually a major problem they're trying to solve with current VR hardware.. Vergence / Accommodation reflex
There is a certain Reflex to your eyes, correlating the inward rotation and the focus of the lens in your eye.
These things are used to moving together in conjunction..
You develop this reflex beginning the day you began to see...
With current vr technology.. it's a fixed focus system.. Which means no matter the perceived distance to object, the lens in your eye has to stay in the same focus distance..
So the problem is, now with vr, you're breaking the reflex, which can have mild to severe consequences..
They're especially worried about this problem for Children, because children are still in the development stage of their ocular circuits and pathways...