Quote Originally Posted by nikkoblu2 View Post
As far as I know, the biggest issue is whether you are coming or going. Head on shouldn't be a problem at all. But, horses can only see between 10 and 2ish (assuming looking straight ahead is considered 12). Their peripheral vision is nearly non-existent.

Granted, they have good hearing, but quietly approaching from the rear could be a problem unless the rider knows you're coming so they can be prepared to soothe their horse and keep things under control.
Actually, that's not correct. Horses can see almost everywhere EXCEPT for directly in front of them and directly behind them.