Cat Vision: Surprisingly Good or Poor?
Did you know that a cat's vision is only about onetenth as sharp as a human's?
Newborn kittens open their eyes between 7 to 10 days old, and it takes a few more days for their eyes to fully open. As their eyes develop, the pupillary reflexes gradually improve, reaching nearadult cat vision by around 4 months. However, even as adults, cats have vision that is merely onetenth as sharp as humans, roughly equivalent to 0.1 to 0.2 diopters. This allows them to discern objects about 10 meters away, but their vision is quite blurred, especially for stationary objects.
Why is a cat's vision so poor?
Cats have a layer of cells called the plexiform layer in their retina, which is also found in the eyes of nocturnal animals and deepsea creatures. This layer helps these animals navigate in lowlight conditions. Even with just a little light passing through the retina, the plexiform layer can amplify the light by about 40%, reflecting it back to the retina. This is why cats can see objects in the dark that are only about onesixth as bright as what humans can see. However, because of this increased reflection, their visual clarity is reduced, making everything appear somewhat blurred.
As nocturnal creatures, cats have welldeveloped lenses and corneas that allow more light into their eyes. However, this also means that their eyes have a higher refractive power, making them essentially nearsighted.
Cats excel in dynamic vision
Cats have the clearest vision at distances of about 75 cm from their eyes. While this might sound like they are super nearsighted, it's actually the perfect distance for them to hunt. Cats have exceptional vision for moving objects, easily catching those that move at speeds of about 15 to 60 degrees per second, which is roughly the speed of a mouse or gecko. However, they struggle with slowmoving or stationary objects, which can seem stationary to them.
Cats' retinal and color vision
While human eyes can discern a wide range of colors, cats' eyes are not as adept in this area. Humans can see all the colors of the rainbow, but cats can only see colors from blue to green, and they cannot distinguish red. This means that the bright colors in cat food are more for our enjoyment than for the cats, who may not even notice them. Cats have more rod cells for black and white vision than humans, which is why they can see in the dark more clearly than we can.
About a cat's field of vision
A cat's singleeye field of vision is called monocular vision, while the combined vision of both eyes is binocular vision. When these fields are combined, they create the overall field of vision. The brain calculates the distance to an object by comparing the images from both eyes, allowing for accurate distance measurement. Cats have a binocular field of vision of about 120 degrees and an overall field of vision of around 250 degrees, compared to humans' 120degree binocular field and about 200 degrees overall. This means cats have a wider field of vision than humans. If a cat is crosseyed, it still has an overall field of vision, but the clarity of the binocular vision may be compromised, leading to potential gaps in their field of vision. This can make it difficult for a crosseyed cat to accurately judge distances and the dimensions of objects.
