As a prey animal the horse has evolved to have incredibly good eyesight.
In order to see, the horse relies on three main elements of vision: the optical properties of the front of the eye; the retina at the back of the eye detecting the image; and the brain’s ability to detect and process that image.
His peripheral vision enables him to see 350° around him, as well as the sky above and the ground below at the same time.
In addition, he has 65° binocular vision in front of him – that’s better than a dog.
The horse’s only blind spots are directly above, beneath and behind him.
Binocular vision in front allows your horse to judge distance, known as depth perception. Horses lift their nose to look at distant objects or turn to face something that attracts them.
Much of a horse’s field of vision is monocular: he only sees through one eye at a time.
The horse’s brain has evolved to cope well with information from each eye independently.
This means he’s good at using other visual cues, like perspective and brightness, to judge distance.
He uses other senses and learned patterns too – he doesn’t rely solely on having two eyes functioning together.
The horse’s visual perception depends on five main factors: depth, colour, brightness, texture and motion.
In darkness, the large cornea and large pupil can expand up to six times their normal size to allow in more light.
The reflective tapetum at the back of the eye further improves light reflection onto the retina. You can spot this structure if you point a torch at your horse in the dark.
In sunny conditions, the horizontal pupil and corpora nigra at the pupil’s edge act like sun visors, while yellow pigments in the lens filter light, reducing glare.
The horse also has a visual streak, where the light-detecting cells in the retina are at their greatest density, which corresponds with the horizon.
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