Horses eyes do not focus the same way that ours do. In order for them to see something far away they must lift their noses and look down the nose, sort of. To see something up close, they must lower their heads. Optimal viewing angle is about 35 degrees down from true horizontal; about the angle a race horse holds his head at a dead gallop. Also, their eyes, though excellent at night vision, are slower than ours to adjust to sudden changes in light level. Thus, when you come out of the woods into a bright meadow, YOU can see sooner than your horse can.