The equine eye

The equine eye is unlike those of most other land mammals – for starters, it’s thought to be the largest, it enables horses to see in panoramic, and in the dark, and that’s just the beginning! Read on to find out more

We reveal how your horse sees the world via six awesome facts about his peepers

1 Thanks to clever yellow pigments at the centre of the eye’s lens, horses can reduce the glare of bright sunlight (something we need sunglasses for). In addition, the corpora nigra (the dark horizontal bit that runs close to the pupil) acts as a sun visor, shading the pupil from glare. But like us, horses still need time to adjust to different light conditions.

2 In humans, 20/20 vision is the mutt’s nuts while equine vision has been recorded at 20/30. This means the details a human can see at 33ft, a horse can only see at 20ft. They do have great night vision thanks to something called a tapetum. This acts like a mirror on the back of the eye – it’s what you see glinting when light hits the eye in darkness (see above).

3 Horses use monocular vision, where separate information comes from each eye. They have a small area of forward-facing binocular vision (where, like humans, images from both eyes are used together). They use binocular vision to scan the horizon (they do this with a high head carriage – pictured) or view things close in front (with a low head carriage).

4 With eyes on either side of their heads, horses have a 350-degree visual field, but they do have some blind spots. The first sits behind the head and extends over the back and tail. The second is below the muzzle and extends about 1m out in front. So, on approaching obstacles, let your horse move his head up and down, and to the side, to assess them.

5 Unlike humans, horses have a third eyelid – a pink membrane that moves over the eye from the inside corner to the outside corner. Its job, along with the upper and lower lids, is to protect the eye from trauma and to seal the eye from danger before the lids close.

6 Like pigs, goats, cows, deer and sheep, horses have what’s called dichromatic vision. This type of vision means they can’t distinguish the colour red. Instead, red appears yellow. Horses also find it hard to tell the difference between yellows and greens and find it easier to see contrasting colours than shades of the same colour.