Article by Karen Dagenais
Have you ever wondered how the world looks to a cat? We know cats see well at night, but what else determines the power of their eyesight? Among the factors to consider are, their field of view, their ability to focus, to judge distance, and to perceive motion and color.
Although we can’t ask cats to read an eye chart like we do, we can use those factors to better understand the many mysteries of cat vision.
How Well Does a Cat See?
Studies on the feline eye have found it to be very different from the human eye. For starters, cats have a substantially wider field of vision than people do. Their field spans 200 degrees, compared to ours at 180. But their distance vision isn’t nearly as good. They have trouble seeing clearly at more than 20 feet. The makeup of the photoreceptors in our retinas are different too. Cats have more rod cells, allowing them to see well in dim light, and to react to quick movement. But they have fewer cone cells, making them less able to distinguish color. In a nutshell, we have better day vision and see colors more vibrantly, while cats are better equipped to function at night.
Can Cats See in the Dark?
The cat’s night vision has evolved out of necessity, to help it become a great nighttime hunter. Its eyes have a high density of rods, the cells that magnify light. It can see with only 15% of the light we need to see clearly. For the size of its head, the cat has very large eyes. It can open its iris wide to let in as much light as possible. It also has a reflective layer at the back of its eye called the tapetum lucidum, which makes a cat’s eyes appear to glow in the dark when hit with a strong beam of light, such as car headlights. And although it may seem like it to us, cats cannot see in total darkness. They do need at least a little bit of light to navigate through dark areas.
Are Cats Color Blind?
We used to think cats only saw in black and white, but now we know that isn’t true. They do perceive some colors, but in a more muted way than we do. Their retinas contain fewer cones, the cells that register pigment. As a result, cats can recognize blues and greens, but have trouble distinguishing red. They often confuse red and green, which is a common trait in human color blindness as well.
Do Cats and Dogs See the Same Way?
The biggest difference between how cats and dogs see is dictated by the shape of their heads. A cat’s eyes are on the front of its head, giving it a visual field of 200 degrees. The dog’s eyes are placed on the sides of its head. Its visual field spans 240 degrees, meaning greater peripheral vision. Both cats and dogs have a smaller central binocular field of vision than humans. They can see at 20 feet what we can see 100 feet away. Both cats and dogs have pupils that dilate to let in extra light, giving them excellent night vision.
Do Cats Lose Vision as they get Older?
Just like people, cats often experience some loss of sight as they age. You may notice how your older cat’s eyes seem a little hazy, with a cloudy, bluish tinge. Most of the time that’s a normal part of aging, and doesn’t affect vision significantly. But if the eyes seem coated with an opaque white film, that could be a sign of cataracts, a more serious problem. Be aware if your cat’s eyes become red or inflamed, as it could be a symptom of high blood pressure or an underlying disease. If you’re unsure, it’s best to consult with a veterinarian.
Cats are independent, resilient creatures, capable of adapting to physical changes as they get older. Even if they don’t see as well later in life, they can rely on their whiskers to help them navigate, as well as other keen senses like smell and hearing.