A brilliant mind said the eye is the window of the soul. Our horses eyes are truly a reflection of their majestic spirits. How many glorious photographs or paintings of horse eye close-ups have you seen? Horses large lustrous eyes pull you with a blink.
Horses have among the largest eyes of any land mammal, as do many of the prey/flight (OMG, Run Away) animals. Think of the eyes of gazelles, antelopes, and such.
Knowing how your horses eyes work will help you understand WHY they behave in certain ways. Like the other Run Away animals we mentioned earlier, horses eyes are set on the sides of their heads which gives them an almost completely circular view of everything around them. Here is the technical breakdown on this - they have a 350 degree view, with 65 degrees being binocular vision and the other 285 degrees monocular.
This wide range enables horses to see whatever is sneaking up on them in an almost complete circle. Their blind spots are believe it or not, right in front of them (really Mother Nature?) and literally right behind them. I suppose that makes sense, for if a mountain lion was sneaking up on them and got that close it wouldn't really matter by then!
Another thing this causes is when a horse jumps, they cannot see what they are jumping over right as they start the jump. The proverbial Leap of Faith!
This combination of binocular and monocular vision causes our horses to have to raise and lower their heads to be able to see and focus. Think of moving your head up and down to peer through readers. Horses do them to focus on close objects and farther away objects.
Horse vision is in the range of 20/33, compared to human 20/20 and canine 20/50. As you can imagine, getting a horse to look at an eye chart to test their vision is kinda hard, so all these numbers are a mix of conjecture and science.
Horses DO have great motion detectors, as that movement out of the corner of their eye is the first alert that the hungry carnivore is creeping up on them (or the modern day equivalent). Most horses will just react with OMG, RUN AWAY rather than hang around to make a definitive decision as to what is actually moving in the distance.
Hopefully, my synopsis of equine eyesight helps you see how your horse sees. Sigh, bad pun, but I'm leaving it....