Cat vision explained…
Have you often wondered how your cat views the world? Cats’ eyes are as fascinating as they are beautiful and in this article we will look at some of their amazing features.
What cats see in the dark
Cats are often thought of as night animals. There can’t be many feline pet parents who haven’t been woken by their four-legged friend asking to go out and party the night away. Clearly, they don’t have a kitty torch to take with them on their night-time adventures, so how do they manage to keep themselves out of trouble and catch the occasional rodent snack on their travels? In other words, how do cats see at night?
So a cat can see in the dark? It is a myth that they can see in total darkness, but they are equipped with the perfect eyes for low light conditions. Let’s take a look at the science behind this.
- Rod to cone ratio
The retina is the light-sensitive layer at the back of the eye which helps to capture an image of the world around us. There are 2 main types of light receptor cells (or photoreceptors), called rods and cones. Rods are great for night vision, peripheral vision, and motion sensing. Cones are colour receptors and more useful for daytime vision. Cats have a higher ration of rods to cones compared to us humans meaning their retinas are much better equipped for low light levels than ours.
- Magic mirror
Hidden at the back of a cat’s eye is a mirrored layer, or tapetum lucidum to give it its scientific name. It sits behind the retina reflecting light, giving a light beam a second opportunity to hit a rod cell if it misses the first time. If you have ever wondered what gives your cat’s eyes a green glow at night or why you see saucer-like car headlight reflections from animal eyes at night, now you know – the amazing tapetum lucidum doing its job of helping with night vision.
- Pupil size
Big pupils may give your cat an appealing wide-eyed look but this is another feature that helps them on their after dark escapades. Cat pupils will dilate to a full circle in low light conditions, enabling more light to get though to those important photoreceptor cells in the retina.
Combined, these adaptations to the feline eye mean that cats are up to 6 times better at seeing in dim light than humans.
Can cats see in colour?
As we discussed earlier, cats have a retina with relatively more rods than cones. So, do cats see colour? The answer is a definite “yes” but, with fewer of these colour-detecting cone cells, their ability to see the full range of hues that we do is reduced.
They only have 2 types of cones as opposed to the 3 that humans have – so cats see colour slightly differently to us. They probably see red and green shades as grey but are much better at seeing colours at the blue and yellow end of the spectrum. This has some similarities to certain forms of colour blindness in people.
So, cats see colour but less vividly than we do.
Why are cat pupils vertical slits?
Cat pupils can change shape from a narrow vertical slit to a perfect round full circle in a matter of seconds. Scientists have long observed that vertical slits are very common in predators. This is likely to be useful for gauging distance accurately, a handy skill if you are trying to pounce on an unsuspecting mouse.
This remarkable ability of feline retinas to change shape has another important benefit. Cats are neither fully nocturnal (active at night) or fully diurnal (active during daylight hours), so their vision needs to be able to adapt to the brightest sunshine but also near darkness. Reducing their pupil size to a slit in bright lighting conditions helps to protect the delicate photoreceptor cells from sun damage.
What else can pupil size tell me?
Feline mind-reading is a skill that most of us don’t have but studying their pupils may give you a small window into their mindset. Pupils will dilate in response to fear, excitement, anxiety and pain. This is brought about by signals from the nervous system in response to these stressful situations.
Equally, small pupils can be a sign that a cat is angry so take care!
Cat eyesight facts
Eyes are amazing. They enable us and our feline friends to see the world around us in fantastic detail but are robust enough to withstand the wear and tear of life. They truly are a wonder of nature. Read on for some fascinating feline eye facts!
- Kittens are all born with blue eyes, changing to their adult colour from 3 weeks old. Read more on kitten development here: <link to kitten development article>
- White-haired cats with blue eyes are usually deaf.
- Cats with heterochromia (2 eyes of different colours) usually have one blue and one green eye. They are normally deaf on the same side as the blue eye!
- Cats are short-sighted. Their vision is sharpest at a distance of 60-90cm with 6m being the maximum distance at which they can see clearly.
- Cats have 3 eyelids! This third eyelid sits at the inner corner of the eye and provides added protection to the delicate surface of the eye.
Worried about your wide-eyed feline? Check out our article on signs of stress in cats here.
If you have any concerns about your cat’s vision we would always advise contacting your vet.