Cat eyes are beautiful and mesmerizing. Humans may attempt to make their eyes look like cat eyes using makeup, but what about the way a cat’s eye functions? How similar is cat vision and human vision? The differences between cat and human eyesight could leave our cats seeing the world a completely different way than we do.
Title Photo Credit: Benjamin Smith via Flickr
Cat Vision vs. Human Vision
Cats and humans have a lot in common as far as structure and positioning of the eyes. These commonalities include:
- The spherical shape of the eyes.
- The main components of the eye (cornea, pupil, iris, lens, retina and optic nerve) are present and have the same basic purposes.
- The eyes are positioned at the front of the head rather than on the sides ( like cows and horses).
Something to keep in mind while exploring the differences in cat vision and human vision is the purpose of a cat’s eyesight. Cats are solitary hunters that hunt small prey, like birds and mice, to survive. Since their main prey does a lot of hiding, it may not be as important to capture all of the visual details of the creature as it is to detect their movement or to be able to hear them. Marking of territory and identification of other cats is primarily done using their sense of smell.
Field of Vision
Despite both cats and humans having their eyes on the front of their heads, cats have a larger field of vision. This difference is due to the fact that cat eyes are proportionally much larger than human eyes. When looking straight ahead, humans have an 180-degree field of vision while cats have a 200-degree field of vision.
For both humans and cats part of the field of vision is only seen by the right eye, part only by the left eye, and part is seen by both eyes at the same time. Binocular vision (the part of the vision field that is seen by both eyes at the same time) is critical in depth perception. Humans have a larger portion of their field of vision dedicated to binocular vision.
It’s no secret that cats see better in the dark than humans do. In fact, cats need only one-sixth the light humans need to see. How do they do it? First of all, as previously mentioned, a cat’s eyes are larger than a human’s. This allows more light to come in.
Secondly, their pupils are oval-shaped rather than circular like human pupils (see the photo of my eyes and Manna’s eyes above). A cat’s pupils are also capable of becoming larger and changing size faster than a human’s pupils. Larger pupils mean more light coming in. How many times have you had to wait for your eyes to adjust to changing light? Cats don’t need to wait anywhere near as long as humans because of how quickly their pupils change size.
The third major component in a cat’s night vision is something called the tapetum lucidum. This is a membrane under the retina of the cat’s eye that works like a mirror. It reflects light coming into the cat’s eye giving it a second chance to be absorbed. The tapetum lucidum is also the reason why cat’s eyes seem to glow in the dark. It is also what reflects when you take a photo of your cat with the flash on. What you are really seeing is not a pair of glowing eyes, but light being reflected off of the tapetum lucidum in the back of the cat’s eyes.
Color or Black and White?
Cats may have beaten us humans with their field of vision and ability to see in the dark, but we win hands down when it comes to color. While cats are not totally color blind, they do not see the entire array of colors that we do. Cats have demonstrated the ability to differentiate between the colors blue, green, and in some studies, yellow. They can also tell the difference between various shades of gray. It is believed that cats cannot see the color red (red objects would appear gray). Cats give up all color vision in the dark.
These color differences are due to the cone to rod ratio in our eyes. Cones help us see color. Rods collect light. Humans have cone-rich retinas even having specific all-cone areas. Cats, on the other hand, have rod-rich retinas. Our eyes give us rich color and detail while a cat’s eyes give them the ability to see in low light situations and easily detect movement.
Near or Farsighted?
For a human being, “normal” vision is measured as being 20/20. That means that when an object is 20 feet away you are seeing it the same way that a “normal” person is seeing it at 20 feet away. If your vision is 20/40, then you are seeing an object that is 20 feet away in the same way a “normal” person would see it at 40 feet away. A person whose vision is 20/40 is nearsighted and required to wear glasses when driving in the US.
Cats are very nearsighted. The average cat vision is somewhere between 20/100 and 20/200. A person who has 20/200 vision is considered legally blind. Cats are very focused on the area immediately surrounding them.
Despite a cat’s vision being nearsighted, it is not close-sighted. Cats can not see anything placed directly below their nose. Their ultrasensitive whiskers are to sense objects that are very close to their heads. Cat vision is sharpest when an object is between 2-3 feet (0.6 – .09 meters) from the cat’s face.