I've always worn glasses but my vision has gotten progressively worse as I've aged - it's not bad, even now, I can legally drive without glasses - but it's enough to be noticeable.
I also was much less prone to motion sickness when I was younger - I would happily read full novels while riding along as a grade schooler.
Turned out that I had similar issues, just not noticeable. It had to do with my eyes not being able to properly maintain a focus at a specific distance over time, and their ability to track properly. I've always been a slow reader - this is at least partly why. I was told that it's also responsible for the fact that I get car sick within seconds of reading in the car, and that it goes away with therapy. Unfortunately, I never did go through with the therapy.