Wow! i've never seen anything like that and I've been in horses for 30 years. I would bet, the problem isn't a matter of blurry but rather more like wlking around with a hand in front of your eye where you can only catch small glimpses of stuff. Given the way horse can react to stuff that suddenly appears it's amazing he's not spookier than he is since much of the time it must seem to him as if stuff appears out of nowhere into his very limited field of vision.