Horses, like most prey animals, have their eyes positioned on both sides of their head. This is so they can have a wide field of vision to watch for approaching predators. Horses have “monocular” vision, meaning that each eye sees things differently and independently. This benefits the prey animal as it allows him to watch his herd with one eye while watching behind him to see if anything is coming after him with the other eye.

A horses monocular vision is not the same as human or predators vision. Horses can look at something with both eyes at the same time and will see the same thing in both eyes. However, he is still seeing two separate views. Horses can switch between monocular and binocular vision depending on the situation they are in. When they are relaxed and grazing, they can use their binocular vision. If they sense something moving behind them, they can immediately switch to their monocular version and continue looking at the grass with one eye, and checking for predators with the other. Once he realizes there is nothing there, he can relax and go back to binocular vision. The switching back and forth between looking at something with one eye vs. something with both eyes is why horses sometimes spook at inanimate objects. Your horse may have seen something with one eye, but when he turns to focus on it with both eyes, until he gets his eyes focused at looking in one direction, it can appear to the horse as if the object has moved.

Horses have large eyes. This is an advantage for a prey animal as it enables him to detect the slightest motion. Horses also move their heads up and down because their visual field is narrow. To see an object clearly, the horse tilts his head so as much of the object as possible fills his eye. Tilting of the head also allows better depth perception. Despite all this, there is still an area around the horse where he is quite blind – in front and behind the horse; about the width of his body. For example, if you can’t see either of the horse’s eyes when mounted or working on the ground, then he can’t see you!

Based on the eye chart developed by the Dutch ophthalmologist Herman Snellen, horses see as well as we do in some instances. Comparing horse vision with humans, research found that horses actually see fairly well from a distance. The Snellen scale for humans is 20/20, meaning that a person can read the same line on an eye chart from 20 feet that the ‘standard’ person can also read from that same distance. Using this Snellen scale, horses rate 20/30 a dog is 20/50 and a cat is 20/75.

Horses are mostly day animals  however they do have some form of night vision. Horse’s eyes are sensitive to weak light, so they can see fairly well at dusk, but they don’t have the ability to adjust their eyes to darkness quickly, which is why they will often refuse to enter a dark building or float from bright sunshine. These are good things to remember when designing your barn. You may want to consider using some of the barn lighting and open stall configurations and windows from Classic Equine Equipment

It was once commonly thought horses were color blind, but in fact they do have the ability to see some color. Their eyes contain light-sensitive cells called rods and cones. Humans have three different types of cones which means we can see all colors. Horses have only two types of cones so see far fewer colors.

Knowing how your horse sees things will not only help you better care for them but will change the way you approach and work around your horse, creating a safer and more trusting environment and a better, stronger partnership.