Humans have a 180 degree field of vision because they have binocular vision, with both eyes located in the front of the head. Horse’s eyes however are located on either side of the head and so they have a 130 degree field of vision on each eye, for a total of 260 degrees. When horses graze, constantly moving their heads from side to side, they have nearly 360 degrees of sight to watch for predators.
Horse Blind Spots
When a horse has its head up it has a couple of significant blind spots including directly behind the horse, directly under the horse’s nose, in the middle of its back near the withers, and directly in front of its forehead. The blind spots directly behind and in front of horses allow for possible spooking. When a horse can’t see it often worries so being careful to make sure that horses can see everything in their environment is important for safety.
Horse’s Visual Acuity
Visual acuity, the ability to focus and see defined detail and contrast, is only a narrow band in the horse’s field of vision, unlike humans who can see detail that is focused with their entire eye. For horses this means that anything in sight above or below this horizontal space is blurry and vague. When a horse is given the ability to move its head freely it has the ability to move the band around enough to be able to clearly see objects and movement in its surroundings. If however the horse is unable to move its head its vision is severely hampered. Horses also have a harder time seeing near objects. Some horses may become nervous when they can’t see things near them for whatever reason and understanding that possibility may help understand the horse’s reactions during training sessions.
Light/Dark Adaption in Horses
It takes a horse’s eye much longer than humans to adjust from light to dark and vice versa. This occurs because their pupils must change shape from narrow and horizontal, which they are in bright light, to oval or a rounded rectangle, which they are in dim light. When leading horses in or out of dim barns from or to brightly lit outdoors, be sure to pause giving the horse time to adjust. Although it takes horses longer to adjust their eyes, their adjustment level is far better than humans, allowing them to see better in both low light and bright light.
Depth Perception in Horses
Horses, since they do not have binocular vision, have very poor depth perception. When the horse is able to freely move its head it can compensate for the lack of perception. However horses being ridden are rarely given the freedom to move their heads, and because of this horses are generally unable to judge distances well. Training a horse to jump obstacles can also teach it how to “know” distances but horses will always have to rely at least partially on humans to judge where to take off from and allow them to see objects by giving them the time and the chance to look at things.
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