No doubt your cat is waking you up for breakfast before the alarm clock. Cats are crepuscular, meaning they are more active at dusk and dawn than during daytime. Nature has equipped your pet with extra advantages to see in these low light conditions. In fact, she can see in the dark roughly seven times better than you. Here’s why:
- Eyes have two kinds of photoreceptors.: Cones interpret colors. Rods detect black, gray and white. Rods are better for night vision. Cats have many more rods than we do.
- Their elliptical pupils act like sunglasses during the day to squeeze out light, because cats are so sensitive to it. In dark conditions these pupils open fully, up to 90 degrees of the iris circumference, to catch as much light as possible.
- Iridescent reflective cells (tapetum lucidum) in the back of the eye amplify even a little bit of light by 130 times. It’s that eerie glow you see in your cat’s eyes when you don’t angle your camera for a flash photo.
- Cats’ eyes also have a special protein called rhodopsin that increases their sensitivity to light for up to an hour at a time.
- Also, tapetum nigrum cells in the back of the eye reduce scattered light from the night sky.
Cats can see beyond the standard light spectrum of humans, into the ultraviolet range. So when they’re staring at an empty corner of the room, there may really be something there that our eyes can’t detect. Researchers think it helps them see where other animals or insects have left trails or markings.
However, cats are short on the infrared side of the color spectrum. They see red only as shades of gray. So the best colors to choose for their toys are blue and yellow or green.
Because cats have fewer eye muscles than humans, their range of clear vision is limited. A cat’s best vision is focused at 6 to 20 feet away. You might call that ‘pouncing’ range. Close up items are a challenge. Have you ever put a treat in front of your cat’s nose but she couldn’t find it? You may have to point to it to help. Her eyes are made to detect motion, not details, even though her nose says food is there.
Cats’ eyes are closer together than a dog’s eyes, facing forward like a person’s. This gives cats much better depth perception than a dog, however, more like yours. Yet they still have peripheral vision almost as wide as a dog’s view, so this gives them a great hunting advantage.
The flicker fusion rate is the rate at which an image is transmitted to the brain and updated every few milliseconds. In cats (and dogs) this rate is faster than for us. It helps them to see clearly while running, or to track fast-moving animals more precisely. But, they will see lines across the TV because it is flickering at a slower rate for us.
Your kitty has a ‘third eyelid’ that is a retractable nictitating membrane in the inner corner of the eye, to help keep the eye moist and to wipe it free of dust every time she blinks. It is meant to stay retracted. If you see it showing, and she has not just woken up or had a muscle relaxer, this could be an indicator that she may be sick or in pain, so a call to the vet would be in order.
All cats are born with dark blue eyes, like humans. Their eyes stay shut for the first two weeks as they continue to develop. By age three months they will have their permanent color, which is often related to the coat color or breed.
Another special trait about a cat’s eyes is that there are usually two colors: one on the outer rim of the iris, and another near the center. Examples of this are green/yellow, green/hazel, turquoise/blue, gold/lemon or rare copper/gold. Deep, solid orange is a trait specially developed by British breeders. A black British shorthair with orange eyes is unforgettable.
Blue eyes occur mostly in all-white cats, and can be an indicator of deafness, because these three attributes (white, blue, deaf) occur together through a genetic mutation. Another genetic surprise is a cat with two different colored irises, such as one blue, one green, which can also occur in white cats. The cat may have deafness only on the blue-eyed side.
What researchers seem to fail to appreciate enough is the beautiful, mystical quality of a cat’s gaze. Her big, sparkling eyes can calm, console, inspire, brighten spirits, speak of adventure, and radiate deep affection for the people she loves. Their gorgeous eyes are probably the main thing we remember when we think about our feline friends.
Heron’s Crossing provides end-of-life care for pets in the Metro Atlanta area. In-home appointments with compassionate vets are available. If you’d prefer a home-like setting away from your home, our Decatur office is also available by appointment.