Posted by Audrey Pavia on 10/10/2007 in Scratching Post Articles
When it comes to their eyes, cats share some similarities with people. After all, both human and feline eyes are located in the front of the face, so both species have good depth of field. A good depth of field allows people to do things like play basketball, drive cars and plant flowers. It enables cats to accurately calculate jumping distances when they are hunting or just leaping from your floor to the couch.
This is where the similarity in vision ends between cats and humans. Cats see better than people when it comes to movement in their peripheral vision. They also have a wider angle of vision. Because cats evolved as predators, their eyes are designed to take in a view of 120 degrees around them. Cats aren’t that good at discerning color and texture, but they have an excellent ability to spot motion in their field of vision.
If a cat feels threatened, its pupils dilate so it can take in an even wider range of peripheral vision, enabling it to see better in the event it has to defend itself. Also, when a cat is preparing to attack prey or even another cat, the pupils become narrow to provide better depth perception.
During daylight hours, however, people possess a much more acute vision than cats. People see details in sharp focus, while cats are believed to have slightly blurred vision. People can also see the full spectrum of colors, while cats are unable to see the color red. The reason? People have many more color sensitive cone photoreceptors in their eyes than cats do.
When the lights go out, though, everything changes. Cats have something called a tapetum in their eyes, which is a reflective layer that increases the amount of light that passes through the retina. This enables cats to see very well in dim light. They can see as well in pitch black as we can see in full moonlight. This is because cats evolved to hunt at dawn and dusk, making them most active in dim light. Cats can see six times better in the dark than people.
What is the anatomy behind all this amazing stuff? The feline eye sits inside a bony structure called the orbit, located in the cat’s skull. The eye itself is made up of the eyeball, and associated nerves, muscles, blood vessels and connective tissue that reside inside the orbit.
Within the eyeball lies the anatomy that allows the cat to see. The eyeball is covered with a white outer layer called the sclera, which rests over the uvea, an area containing blood vessels. Covering the outer part of the eyeball is the cornea, which is clear, and refracts light onto the retina, which transforms light rays into nerve impulses. These impulses are relayed to the brain via the optic nerve. The cat’s brain then makes sense of the rays and converts them into images that the brain can understand.
The next time you look into your cat’s eyes, think about what amazing organs these are. Without them, your cat wouldn’t be the incredibly special creature she is. Seeing is believing.