Anderm, if you do a lot of close work, like reading, your eyes will tire and need a rest. Note that they recover after you start looking at the distance for a while.
You say you weren’t born near-sighted. At what age were you tested? Eyes generally deteriorate in some one who has the genes for nearsightedness until they reach maturity. I didn’t start wearing glasses until I entered grammar school, but I’m sure I needed them sooner. My vision gradually worsened over the years, finally actually improving slightly in my dotage. They improved tremendously 10 years ago, when I had PRK :).
(I didn’t check the archives yet. I’ll do that later.)
Let me add, in support of the hereditary theory, that everyone in my family wears glasses, and thick ones too, and I had (at one time) two sisters and two brothers, and now have a host of descendants from them. Without exception. You can argue that in my immediate family, it was the environment, but not convincingly. That argument would not hold for nephews, grand-nephews, nieces, etc.
Beside just getting the eye to grossly focus properly, the smoothness of the cornea also has an effect. Most corneas are not perfectly shaped. This would be just like have a lens that was not ground perfectly (has small surface bumps on it). Small surface imperfection limit how sharply a lens can focus. So people with smoother than “average” cornea will be able to see better than the 20/20 average.
There is a new lasik system in the works called something like “custom surface ablation” that maps all the little micro imperfections and corrects all these while it is doing the gross reshaping. 20/10 or better results will supposedly be common with this procedure.
There is no 20/1. Human eyesight according to the articles I have read is theoretically maxed out at about 20/5, and that is with full correction of about 60 different abnormalities when eyeglasses typically take into account only a few of those abnormalities. There are labs working on continuously correcting optics that bounce lasers off the retina that will correct all the abnormalities, but the rigs are huge and cannot move. The biggest increase would be in night vision.
Standard/normal vision is 20/20, but this is by no means the mean or the mode. Someone with 20/20 will be able to spot the double star in one of the Dippers (I forget which one) that the Romans made their officers see before they made them officers.
I’ve been on a road trip with a former Navy navigator (Orions like the one the Chinese held last year) with 20/15 natural vision, and it was really irritating having him read road signs before I could even see how many lines of writing were on the sign.
I’ve read about these experiments. The theoretic limit to human vision is related to the number and size of the rods and cones in the retina. In these experimental procedures, they can evidently focus light so perfectly onto the retina that it messes up the ability to see colors correctly, because a particular spot of light will hit only on a single cone, which individual cone will show only one color. A slight smearing is needed so that a spot of light will hit multiple cones and thereby allow your brain to manufacture a particular color.