Sorry to catch on to this thread late, but crawling and swimming can be related to vision since they involve cross lateralization of the brain. IF a child doesn't learn to crawl properly, then they're often at risk of not using their brain and body evenly and their neurological wiring going haywire.
This happened with my ds since he was born with visual deficits as well as a neck injury (torticollis) and other physical issues. When ds was very young, it was like he had a stroke or hemiparesis on his left side. He would over compensate with his right and throw his brain/body off kilter so to speak. He spent so much time and effort avoiding his left side, his neck, and tummy muscles. Well, his early development was completely off as a result.
If you think about it, we use our visual skills very differently when we crawl and swim than when we sit and read a book, for instance. A child who skips through crawling to walking learns to compensate. Neurologically, the neural pathways can go into another direction; for example, they may take Route 66 when they should be taking Route 95. Once a child learns to compensate, then it can be very difficult for them to unlearn or get out of that default without more direct intervention.
Neurologically, one of the goals with vision therapy should be for the child to deal with those compensations and get the brain to learn new neural pathways. They prism glasses and exercises should, ideally, force the child to accept a new reality of looking at the world instead of the default, compensated one. The child therefore will naturally dislike (or even hate) the vision therapy exercises at some point because it basically forces them to change what they've accepted and been relying on. If I go back to my analogy about taking Route 66 instead of Route 95, vision therapy should help a child find and take Route 95.
Remember over 80% of what we encounter on a daily basis involves the visual system. Visual acuity (20/20 vision) is only a small part of the visual system. Visual system also involves getting your body and brain to react to what you see. That involves neurons and neural pathways being fired up and doing their job.
Hope this helps and makes some sense.
