First a disclaimer... I have no particular expertise in this area and intend only for it be an interesting thinking point. Take it with a grain of salt. That said, I'll start with my own story.
About a week ago, I got contact lenses for the first time in about 15 years. I am mainly nearsighted, but have alittle bit of astigmatism. Normally a small amount of astigmatism can be corrected by overcorrecting the nearsightedness, which, because of the complexity (and expense) of correcting astigmatism with contact lenses, is usually tried first (with glasses, it's all the same so they just do right the first time).
It turns out, I'm one of the weird ones who's eyes just won't let the overcorrection make up for the astigmatism. Over the past week, my eyes were trying though. My vision seemed to go in an out throughout the day. If I ever just let my eyes relax though, my vision would always go out. I wasn't ever conciously trying to make my eyes adjust, but there was definitely something subconcious going on.
The interesting part to me was noticing that I was so much less aware of everything around me. This was not only true of the times when my vision seemed to be the best, but was actually most true when my vision seemed to be at its best. Somehow putting the mental effort in to self correcting my vision (even subconsciously) was reducing the amount of mental capacity I had to analyze what I was seeing. While I could look around and see everything around me, I just didn't have that natural awareness of things like "while pulling out of this street, I need to be aware of the cars 10 seconds out to the left" and lost even more mental capacity as I had to make a conscious and deliberate effort to compensate.
The first time I saw the optometrist when getting my contacts, I was able to finagle my vision in to being close enough to 20/20 for the optometrist to let me go, but on the followup today, I just let my vision be where it wanted to be and they gave me some of the fancy astigmatism contacts. My vision is very very nearly as good as it is with my glasses and the awareness problems are gone.
So how does this relate to basketball? I've heard so many times about players who "just see the court better". It's been said about ever great passer that ever played. They clearly have it going right already, but what about those less fortuante players that just can't ever seem to be aware of what's going on around them? The Z-Bo and Trout's of the world? Is it possible that they have natural vision problems that the "vision control part of the brain" is working overtime to correct, thereby robbing them of potential court vision? Or perhaps they already know they have astigmatism (or somethign similar) and just don't have it treated properly.
Some people are just blessed with natural ability. Usain Bolt was just built better for sprinting than Bill Walton. Some people are just going to have better vision. As far as I know though, what I've described in this post isn't something the normal optometry community considers, and we may have some players that are unnecessarily hold thier own "court vision" back.