When it comes to understanding how a horse’s vision works, there are several myths surrounding what they can and can’t actually see. For example, many people insist that horses can only see in black and white, and other people are convinced that horses don’t have any depth perception.
Although we still don’t fully understand how a horse’s eyes work, we have come a long way in discovering how they actually see the world.
One of the many interesting things about horses is that they have the largest eyes of any land mammal. But, having big eyes doesn’t necessarily mean that they have the best eyesight. There are limits to what horses can see, and learning about them will help us understand how much trust they actually place in us.
How Does Horses’ Vision Work?
Like a lot of other mammals, horses’ eyes are positioned laterally – which means that they’re on the side of their head, rather than the front like ours.
Having laterally positioned eyes helps them get a wider field of vision, which means they’re able to spot any danger long before it arrives. Although their long distance vision is pretty impressive, horses can struggle to see objects which are close to them.
Like most animals, the eyes of a horse are made up of these things called rods and cones. These help horses see in both low and high levels of light. But what exactly do they do?
Rods are responsible for the perception of light – which is also referred to as scotopic vision. This is what helps horses to see in lower light situations.
Cones, on the other hand, are responsible for photopic vision. Horses have two cones, which both control what colors they can see. The short-wavelength allows them to see blue, and the medium-wavelength allows them to see green. There is also a long-wavelength that allows you to see red, which humans have and horses don’t.
Forms Of Vision
As well as rods and cones that allow horses to see in a range of light conditions, they also have two forms of vision. Horses can easily switch between the two when necessary.
Monocular Vision
Monocular vision allows horses to use both eyes separately at the same time. This means they almost have a 360° view, however, they do have two blind spots – one directly in front of them and one directly behind. Whilst using monocular vision, a horse’s perception of depth is limited.
When using their monocular vision, horses are able to see any approaching threats.
Binocular Vision
This is pretty similar to how our eyes work and allows horses to use both their eyes to see directly in front of them. Whilst using binocular vision, horses are able to see objects in front of them, and are also able to judge distances. However, horses do still have a blind spot, which is roughly 3ft to 4ft in front of them.
Blind Spots
As mentioned previously, horses do have certain blind spots because of where their eyes are positioned.
They have two main blind spots. The first is directly behind them, and the second is between three to four feet in front of them. They are unable to see in both of these areas when using either monocular or binocular vision. However, when they are using monocular vision, they have marginal sight on either side of their backside.
Breaking Down Myths About Horses’ Vision
There are a lot of myths surrounding what horses can and can’t see, which leads people to wonder what is actually the truth. In this next section, we’re going to answer some of the most common questions surrounding the way in which horses see.
Can Horses See Color?
Contrary to popular belief, horses can in fact see in color. What colors they can see, however, depends on the wavelengths of their cones.
As mentioned previously, there are three wavelengths: short, medium, and long. Humans have all three wavelengths, which is also referred to as trichromatic. This allows us to see the full spectrum of red, blue and green.
Horses, on the other hand, are dichromatic. They only have two wavelengths (short and medium) which allows them to see only blue and green. Interestingly, their middle-wavelength cone (green) allows them to see fractions of red.
It’s thought that horses only have a short and medium wavelength as when they first evolved they were most active during dawn and dusk – times when there is little need to see red.
Despite being able to see some color, horses do have color deficiencies which makes some objects harder to see – but not completely invisible. This is why most horse jumps are painted in bright, contrasting colors, as they’re much less likely to knock them down.
Are Horses Able to See In The Dark?
Quite often, horses will be hesitant to ride into a dark area. This leads many to think that horses are unable to see in the dark, but this isn’t the case.
If you’ve ever witnessed horses roaming around a field in the dark, they can move around without bumping into anything. Also, if horses had poor night vision, they wouldn’t be able to graze at night.
At the back of their eyes, horses have a membrane called the tapetum lucidum. This membrane is a retroreflector which reflects visible light back through the retina, which increases the amount of light in the eye. This, along with rods (mentioned earlier, which allows horses to see in low-light), gives horses the ability to see in the dark.
Although horses have pretty good night vision, they struggle with quick changes in light. This is why horses are often hesitant before entering dark areas, as their eyes need a few seconds to adapt to the sudden decrease of light. This is the same for sudden increases in light.
Do Horses Have 360° Vision?
Although horses have a pretty wide range of vision, they don’t quite have a full 360° scope. However, their large eyes give them a viewing range which is bigger than most animals. Whilst using their monocular vision, they are able to see a 350° range, without even turning their head.
There are only two places that a horse can’t see without moving, and that is their blind spots. These are directly in front and behind them.
Horses’ binocular vision has a much shorter range, but it does allow them to see in front of them, with the exception of a 3 or 4 ft blind spot – this is why horses struggle to see what’s directly in front of them without moving their head.
Do Horses Have Depth Perception?
As horses’ eyes are on the side of their head, it’s been long thought that they’re incapable of being able to judge distances well, so they have poor depth perception. This is far from the truth, however, there is a short period of time in which a horse is unable to see an obstacle in front of them that they’re approaching.
Horses can judge depth with just one eye. As their eyes are positioned slightly forwards, they have a slight overlap of around 55° to 65°.
By raising, tilting or lowering their head, they are able to see into their blind spots, which helps with their depth perception. This is only applicable to their monocular vision, as they usually have excellent depth perception when using their binocular vision.
Are Horses Nearsighted?
Another common misconception is that horses are nearsighted, and struggle to see things from a far away distance. A lot of research has been done into the near and farsightedness of horses, and it’s thought that around a third of domestic horses are nearsighted, the rest are thought to be farsighted.
If we also compare a horse’s eyesight with our own, a human with “perfect vision” is thought to have 20/20 vision. Horses’ vision ranges from 20/30 to 20/60. This means that they can see something 20 feet away that an average human would be able to see 30 to 60 feet away.
Although near and farsightedness can range in horses depending on their breed, there is the argument that horses wouldn’t have survived as long as they have if they weren’t able to see approaching danger.
Do Horses Need To Use Both Of Their Eyes To See Something?
Interestingly, a horse is able to see something with one eye that both sides of their brain are able to understand. As mentioned earlier, a horse can use both monocular and binocular vision at the same time – each on either eye.
Sometimes horses may shy away from something they’ve come across before, but this isn’t because they’ve only seen it with one eye. This is usually because of the contrast of light and shadows which makes the object appear different.
Frequently Asked Questions
What Causes Vision Problems In Horses?
Vision problems can arise from a number of different things such as cataracts, which can block or blur any light entering a horse’s eye. Horses can also develop cysts at the top of the pupil. These will float into a horse’s line of vision, and will often spook them.
You can usually tell if a horse is experiencing any vision problems if they have a sudden change in behaviour. This can include shying away, spooking, and reluctance to enter a stall – but these behaviours may also be a result of behavioral, orthopedic and neurological issues. If you notice a change in your horse, seek medical advice from a veterinarian.
Eye problems can also be noticed if there is a change in eyeball coloration (white or blue hazes), redness and hair loss around the eyes, and if they’re squinting. Horses may also attempt to rub their eyes if they feel any discomfort.
Do Horses See Things Bigger?
Horses have the largest eyes of any land mammal, and their eyes are eight times larger than humans. Because of their large eyeballs, horses have oversized retinas which magnify their vision. Any close up object looks 50% bigger than they would appear to us humans.
Despite their larger eyes, horses are unable to pick out the fine details of an object in the center of their visual field.
