Have you ever wondered what it’s like to see the world through your cat’s eyes? Do they have better eyesight than we do? And what are they seeing when they stare off into the middle distance like that? That’s just downright creepy! How exactly are cats seeing the world? What colours can cats see?

Cats have remarkable senses that allow them to function as highly efficient predators. They have an acute sense of hearing and smell, and their whiskers (vibrissae) allow them to precisely detect their prey’s position. Cats are always on high alert and can hear much more than we can. It’s probably not ghosts that have caught their attention though when they seem to stare at nothing. They are simply scanning their environment for either a threat or a potential mouse-sized snack and can just pick up on a lot more noise than we can. 

But what about their eyesight? Let’s take a closer look!

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What colours can a cat see? Are cats colourblind?

Firstly, let’s examine the types of colours cats can perceive in the world around them. The retina sits at the back of the eye and is covered in photoreceptor cells, which are essential for vision. The two classic types of photoreceptor cells are rods and cones. Rods are adapted to allow vision in dim light, whereas cones work best under bright conditions. Cones are the photoreceptor cells that are responsible for colour vision.

Cones come in three flavours (in mammals anyway!) – S-cones, M-cones and L-cones. Humans normally have all three types of cones, and ten times as many as a cat; which allows us to perceive the world in a huge spectrum of colour. It is thought that we evolved to have fantastic colour vision because our primate ancestors would have needed to perform visual tasks like foraging, reading the emotions of our companions and spotting camouflaged predators in order to survive. 

Can cats see as many colours as humans?

Cats are ‘dichromats’ -they only have two types of cones. This is common for most mammals and means they cannot see as many different colours as a human can. Dichromats see the world in a somewhat similar way to a person with protanopia, which is a fancy word to describe colour blindness. 

Do cats see in black and white?

While it’s not true that cats can only see the world in shades of grey, cats do see less colour than we can. Colours near the red end of the spectrum can be more difficult for cats to make out. Reds and greens can appear greyish and are hard for cats to tell apart. It is thought that cats can see blues and yellows most clearly. But if you were to look at the world through your cat’s eyes, you might find it looks quite desaturated and not very vibrant compared to how we’re used to viewing our environment. 

Do cats have night vision?

Cats have large eyes, which flood the retina with as much available light as possible. The retina is the area at the back of the eye, covered in photoreceptor cells that convert light into electrical signals. These signals travel from the retina, down the optic nerve to the brain, where they are translated into the images you see. Cats need to see well in low light as their prey is most active at dawn and dusk. Having large eyes is just one adaptation to help them see in the dark. 

I mentioned cones earlier, and this is where the other type of photoreceptor cells come into the mix. Rods are photoreceptor cells in the retina that function better in low light than cones. Cats have six to eight times more rod cells in their retina than humans do; enhancing their ability to see in the dark.

Why do cat’s eyes glow in the dark?

Cats have a special layer of tissue in their eye that helps to reflect light back into the retina, called the tapetum lucidum. It lies immediately behind the retina, and it enables the cat to see in much dimmer light than would otherwise be possible. Perhaps you have noticed the eyeshine produced by the tapetum lucidum when your cat looks directly into the camera? When light from the camera shines directly into the eye, it is reflected back by the tapetum lucidum, causing the pupil to appear to glow. This is known as ‘eyeshine’.

Humans do not have a tapetum lucidum, but we might get a ‘red eye’ effect in photographs. The ‘red eye’ effect is caused by the reflection of the blood supply at the back of the eye. Interestingly, cats with blue eyes may display both eyeshine and the ‘red eye’ effect in photographs. So if you own a blue-eyed cat, that’s something particularly cool to look out for.

These night-vision adaptations enable cats to see in darkness, using roughly one-sixth the amount of light than humans need. 

Do cats need specs?

Having more rods than cones means that cats don’t see as well as we do when light is abundant. Cats can’t see in as much detail as we humans do. The ability to recognise small details with precision is known as visual acuity. I’d say without my contact lenses I’m able to focus to about two metres (just over six feet), and then things start to lose their detail. Cats do a little bit better than me, being able to see clearly to a distance of around six metres (or twenty feet), but most humans can manage twenty or thirty metres.

We’d have to describe cats as nearsighted, meaning they cannot see far objects well (and certainly wouldn’t get their driving licence without some form of corrective lens)! A cat’s pupil is able to contract to a small slit to reduce the amount of light hitting the retina, which helps to improve their visual acuity a little bit in strong light. 

Feline field of vision

Your field of vision is the angle of the world you are able to view at any one time without moving your head. Humans have a field of view of about 180 degrees, but cats can see a wider area, at around 200 degrees. The placement of the eyes plays the biggest role in field of vision. Prey animals like horses have a wider field of vision as their eyes are set to the side of their head, allowing them to scan their surroundings more easily for predators. Cats have a more central eye placement, which gives them better depth perception at the expense of field of view. Depth perception is more valuable to a hunter like a cat (or a jumper, like our primate ancestors).

Another difference particular to the eye of a cat is the structure known as the third eyelid. The anatomical term for the third eyelid is the nictitating membrane. Perhaps you’ve noticed this thin white membrane, as it flashes across the surface of your cat’s eye when they blink? When your cat is sleepy or not feeling well, the nictating membrane can also become more visible as it is only partially withdrawn. 

The purpose of the nictitating membrane is to protect the eye from damage. It’s not uncommon for cats to get injured by their prey and being scratched in the eye could be a serious matter. Cats are able to bring their third eyelid across as an extra layer of protection for the surface of their eye. 

So what would the world look like, if seen through a cat’s eyes?

Well, the answer is probably quite dull and blurry! If we looked through the eyes of a cat, there wouldn’t be as much colour to make out, and many objects further than twenty feet away would seem out of focus. But in low light, we’d be able to make out much more, and we’d also have a wider field of vision, a bit like viewing the world through a fish-eye lens on a camera. 

If you’d like to see for yourself, TrustedHousesitters have created an interactive tool that can replicate a cat’s view of the world. You can either upload a photo or use the tool in real-time, using your desktop or mobile camera. You can compare the vision of dogs, birds and rabbits using this tool too.

Sarah Elliott BVetMed MANZCVS (Feline Medicine) MRCVS