Just like us, cats have two eyes, but what and how they see isn’t exactly like humans.
Field of Vision
A cat’s 200 degree field of view is wider than the 180 degrees that a human sees, which means that cats see things further slightly behind their head in their peripheral vision. This is a real advantage to hunters looking for prey as well as helping small animals keep a lookout for predators who might keep them harm.
Cats having forward-facing eyes also gives them binocular vision, where each eye has overlapping fields of view. This gives cats depth perception for accurate pounces onto prey. This also helps cats make their graceful leaps and accurate landings on small ledges or branches.
Cats like Ashton with only one eye don’t have binocular vision, and they have to learn to compensate. Ashton doesn’t leap onto unfamiliar objects because she can’t measure the distance there with her eyes. She’s also much more likely to lose small objects when they are tossed in the air, but she compensates by listening for the sound of them striking the floor.
Seeing Colors
Cones are the light receptors in your eyes that work best in bright light. Human eyes have 10 times the cones than cat eyes, giving them the edge in seeing color, but cats do have cones. They can distinguish colors from each other, but they are better able to distinguish colors at the blue-purple end of the spectrum. They see even further into that end of the spectrum than humans, and are able to see ultraviolet light that humans can’t detect with our eyes.
Have you ever used a black light to see down wayward cat urine in the house? Your cat’s vision may help her see that, too. That goes a long way toward explaining feline urine-marking on walls; it’s not just a scent mark but a visual indicator, too, like spray-painting graffiti that says “I was here!”
Distance Vision
Humans can adjust the shape of the lens in our eyes to focus at various distances. Cats can’t adjust the shape of the stiffer lens of their eye and instead actually shift the location of the lens in the eye slightly to refocus, giving them less flexibility in their range of vision.
As a result, while humans can focus on objects 100-200 feet away, a cat needs to be within 20 feet to focus on an object. That’s right… cats are nearsighted.
Night Vision
Rods are the photoreceptors in your eye responsible for seeing in low light. Cats have six to eight times the number of rods in their eyes than humans. This helps cats make the most of low-light conditions for hunting or making their way around the house in what humans perceive as darkness.
When you trip over your kitty on your way to the kitchen for a drink in the middle of the night, your cat was able to see just fine. It was you with your lesser rods who couldn’t see your way in your house.
It’s easy to make assumptions that when your cat sees something you don’t — or doesn’t see something you do — that they’re being fanciful or difficult, but keep in mind that your kitty sees the world differently than you do in many ways.
References and Further Reading
The Journal of Comparative Neurology, A quantitative analysis of the cat retinal ganglion cell topography
Animal Eyes, Michael F. Land, Dan-Eric Nilsson, Animal Eyes
Handbook of Sensory Physiology, The Visual System in Vertebrates
Vision Research, The schematic eye in the cat
Proceedings of the Royal Society B, The spectral transmission of ocular media suggests ultraviolet sensitivity is widespread among mammals
The Evolution of binocular vision
Photo Credits
depositphotos/RasulovS
depositphotos/wvita
