Cat vision and how cats see directly relates to the position of feline eyes. Situated at the front of the cat’s face, the design helps cats to hunt in low light. While cat eyes work similarly to human eyes, feline vision evolved to make the most use of available light and tiny movements. Vision brings the cat a finely tuned understanding of spatial relationships, and that coupled with superb motor skills—as well as hearing and scent sense—make Kitty an exceptional hunter. How cats see and feline eyes also play an important role in silent feline communication.

Proportionally, the cat has the largest eyes of any carnivore; a similar eye-to-face ratio in people would make our eyes eight inches across. By facing forward, the cat’s field of vision overlaps and gives her three-dimensional sight, which is critical when judging distance. This provides Kitty with 130 degrees of binocular vision, compared to our own 120 degrees. In addition, cats have 155 degrees of peripheral vision (compared to humans’ 90 degrees) and are experts at detecting motion from the corners of their eyes.

Cat Eye Colors and Their Rarity Chart (Courtesy of Caster.com)

Caster offers a nice overview of cat eye color in this post, and generously allowed sharing of the diagram, below.

How Cats See

Cat eyes function like an organic camera. They record images carried by light to the brain, where vision is translated into meaning.

The eyeball fits in a cradle of cushioning fat deep inside a bony protective socket in the skull. Eyelids support the front of the eye, sliding like vertical windshield wipers over the surface of the eyeball lubricated by a thin layer of tears. Cats also have a third rarely seen eyelid, called the nictitating membrane or haw, at the inside corner of the eye. This membrane lubricates and protects the eye, sliding sideways across to swipe the surface clean. A visible nictitating membrane often indicates pain.

A clear cornea covers most of the front surface of the cat’s eye with the outer edge called the sclera (“white of the eye” in humans). A thin layer of tissue (conjunctiva) covers the sclera, the inner eyelid, and the sides of the nictitating membrane. Tears from glands in these structures lubricate and clean the eye and contain immune substances to fight bacterial infection. Directly behind the cornea is the anterior chamber filled with aqueous fluid.

Organic Camera: How Feline Vision Works

The pupil, the dark center opening, works like a camera shutter to control the amount of light passing into the eye. The beautiful colored portion of the cat’s eye (iris) is a figure-eight muscle that responds to light, opening and closing the pupil to regulate the amount passing into the structure. In very low light, the pupil opens wide in a circle to capture as much light as possible. In high light the iris closes the pupil to a vertical slit. The cat’s eyelids may further reduce the amount of light by squinting; this also helps to focus images for the cat.

Near vision isn’t as sharp as ours, because the muscles that focus the lens are rather weak. Kitty must focus long and hard on stationary objects, near or far. Cats typically rely on movement to locate and identify objects.

Light passes through the pupil and focused by the lens onto the retina at the back of the eye, like a movie projector shining an image onto a screen. The area between the lens and retina contains gel-like vitreous which helps hold the retina in place. Millions of light-receptor cells on the retina called rods and cones gather the information. Other cells send signals through the optic nerve to the brain’s visual center, where the impulses are translated into meaningful images.

Do Cats See In Color?

Rods allow Kitty to see shades of white, black and gray, while cones provide color sense. Although the cat does have the ability to detect differences between certain greens, blues and yellows, it’s uncertain how important colors are to cats. In some tests, it appeared cats care more about patterns, like spots and stripes, than specific colors. So although Kitty sees color, he probably just doesn’t care. Check out the video, below, for additional examples of cat (and dog) color perception.

Cats need only 1/6th the illumination level and use twice as much available light as people because their rod-to-cone ratio is much higher than ours. Low light vision benefits from a layer of highly reflective cells, called the tapetum lucidum located behind the retina. The tapetum lucidum captures and reflects back any light the eye captures, in effecting making the light do double duty. It’s this eerie reflection you see at night when light shines in your cat’s eyes.

Eye Injuries

The eye is prone to conditions which can be extremely painful to the cat and require immediate veterinary attention. Signs of a painful eye include squinting, tearing, avoiding light, and tenderness to touch. Flat faced breeds of cat that have more prominent eyes like the Persian may require routine cleaning of their eyes. Signs of injury and/or disease may include any kind of eye discharge, redness, crusting, cloudiness to the eye, or a hard or soft eye.