The Anatomy of a Cat's Eye
Compared to other animals, the eyes of a cat are pretty unique looking. They may be large, intense, and beautiful—but these seemingly cosmetic features serve the greater purpose of helping a cat survive.
Cat Vision: As Different as Night and Day
The most intriguing feature of a cat's eyes is its sheer size. If we look at the proportions carefully, their eyes are quite large in comparison to the size of their head. This is typical of nocturnal animals (although cats are technically crepuscular), as large eyes allow them to take in much more light.
Even so, saying that cats see well in the dark is really only a half-truth. They can see about six to ten times better than humans, but they cannot see in complete darkness.
The mysterious fluorescent shine of a cat's eyes, when caught in a beam of light, is caused by a structure called the tapetum lucidum, located directly behind the retina. The cat's tapetum works like a mirror, allowing lights to bounce off of it and increase visual sensitivity. It works similarly to those reflective lane markings on the highway.
A cat's daytime vision is inferior to the daytime vision of a human. During the day, cats will be unable to focus properly and may see things as somewhat blurry. Cats are also unable to perceive bright, vivid colors in the daytime.
While their color vision may not be as complex ours, they have shown to respond to the following colors:
However, color does not seem to play a vital role in a cat's survival. They usually prowl at night, so color is rarely a factor in a successful hunt.
Cat Pupils and Light
A cat's pupil is elliptical (vertical) when it's bright, or large and round when it's dark. The pupil is very sensitive, and expands or retracts dramatically, depending on the environment.
A cat's eyes are specifically designed to register the slightest movement. Have you ever found your cat looking up at something that is not there? No need to worry, your home is not haunted. Chances are, your cat was seeing something as subtle as a tuft of fur floating in the air. While "perfect" human vision is 20/20, a cat's vision can range from 20/100 to 20/200.
The Third Eye(lid)
Cats also have a third eyelid. While this cannot be seen when a cat's eyes are wide open, a hint of it can be seen when they wake up. The cat's third eyelid is located in the inner corner of the eye, and can help prevent cornea damage. It appears as a whitish film that, in some instances, may cover most of the eyeball. However, the third eyelid should not be showing under normal circumstances—as this can point to eye irritation. Protrusion of the third eyelid may be a signal that a thorough veterinary exam is necessary.
A Not-So-Fatal Flaw
A cat has a small blind spot directly in front of them. An animal of prey would rarely be that close to a cat, so it's not considered a fatal flaw.
It's All in the Eyes
The eyes of a cat play a vital role in its ability to survive for many years. They allow this magnificent animal to stalk and pounce upon their prey, or slink around in the dark. It is ultimately thanks to their eyes that we are able to enjoy our feline friends' companionship today.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.