Without a doubt, yes, all sorts of compensation are at play. Still, the fact remains that he reliably picks up my relatively subdued sign language at great distance. And swimming, even in rough sea, if he can't pick out the floating stick, he'll look to me, I'll point, he will scan as directed, and head straight for the thing. One way or the other, all this is decent visual performance, nothing nearsighted about it.
We all compensate for the handicaps we have. I'm also was very nearsighted since I was about 11. I did get glasses but didn't use them while skiing, not very confy under the helmet. But I could still see who of my classmates were at the bottom of the mountain, about 300 m away, because of the movement pattern. I have no clue how we know how dogs have bad eye sight, I can't even begin to imagine how we know about T-Rex. I have to look at that link someone posted.
