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We’ve all seen a pair of glowing eyes shimmering in the darkness. If you wake up in the middle of the night and go to the kitchen for a glass of water, you might have seen your cat’s glowing eyes staring back at you. Have you ever wondered what makes a cat’s eyes glow?
The glowing can be attributed to a component called the tapetum. This fascinating phenomenon serves a valuable purpose. In this article, we will explore what causes eye glowing in cats and how it affects their overall vision.
What Causes Cat Eyes to Glow in the Dark?
It is a common misconception that cats are nocturnal. Contrary to popular belief, cats are crepuscular. Crepuscular animals are designed to see very well in low-light conditions, and anyone who has owned a cat can confirm that they are much more active at dawn and dusk.
However, crepuscular animals share some characteristics with nocturnal animals, including glowing eyes. So, what exactly creates this glowing effect? It is a component called the tapetum lucidum, which translates to “shining layer.”
Purpose of the Tapetum Lucidum
The tapetum lucidum is an incredible part of the eye’s anatomy that helps enhance vision during low-light hours. The tapetum lucidum1 acts as a biological reflector system, providing light-sensitive retinal cells with a second opportunity for photon photoreceptor stimulation. When light shines into the eye, it hits the photoreceptors (light receptors) at the back of the eye (the retina), which send information to the brain via nerves.
Any light passing through the retina will reach the tapetum lucidum, which then reflects the light back to the retina, like a little mirror. This gives it a chance to pick up more light signals. However, not all of this light is picked up by the retina, and it appears as a green glow or eye shine as it bounces off the iridescent tapetum.
Cats are much better at seeing in low-light conditions than humans. They can alter the intensity of light falling on their retina 135-fold compared to tenfold in a human’s eye2.
Why Don’t Humans Have the Tapetum Lucidum?
There’s a pretty simple explanation for why humans don’t have a tapetum lucidum. As you know, we aren’t crepuscular or nocturnal but are diurnal and see best in daylight hours. We also don’t need to see in low light to survive. Cats and many other animals require this trait to hunt and protect themselves from predators.
Do Cats See Better Than Humans?
Deciding who can see better between cats and humans is difficult. After all, they are equipped with different features that help them see best for their species. For example, humans see a broad spectrum of colors that many animals cannot. Since we can see best in broad daylight, this feature comes in handy to us.
When it comes to the color spectrum, your cat sees similarly to a human being who is colorblind. They see the world in shades of gray and are good at picking up on blues and yellows. However, cats can have quite a hard time distinguishing other colors, mainly red and green.
They make up for what they lack in color detection with their field of vision. Cats have a much wider vision field than we do, which is incredibly useful in spotting threats approaching them from either side.
Cats can see 200 degrees on either side, while humans can only see 180 degrees.
Why Do Cat’s Eyes Glow Differently?
Most of the time, your cat’s eyes should glow yellow or green. Yellow-orange combinations are also often seen. The color varies based on their irises. For example, if your cat has blue eyes, they might reflect colors different from those of a cat with golden eyes.
If your cat’s eyes glow two different colors, it might indicate a problem with them. It’s best to have them examined by your vet to ensure there is no underlying problem causing them to reflect two distinct colors.
Do All Cat’s Eyes Glow in the Dark?
All healthy cats should have glowing eyes at night. It is a trait of many animals to see in low-light settings. However, if you notice that your cat’s eyes do not glow at night, it could signal an underlying health condition.
Health Conditions That Prevent Glowing
Here are a few conditions that might make your cat’s eyes stop glowing:
Glaucoma
Felines can get glaucoma just like humans. With this condition, a watery fluid called aqueous humor accumulates in the front part of the eye and is unable to drain properly. This fluid accumulation results in increased pressure in the eye.
Left untreated, glaucoma can lead to partial or total blindness and is very painful. Some breeds, like the Burmese or Siamese cat, are predisposed to this condition.
Cataracts
Cataracts are an increase in the opacity of the eye’s lens. Because they develop a cloudy appearance and are more dense, they can cause the tapetum lucidum not to reflect appropriately. Specialist surgery can treat cataracts.
Conjunctivitis
Conjunctivitis is a prevalent feline eye disorder. An inflammation of the thin mucous membranes on the inner surface of the eyelids causes it. You might notice a crusty or runny discharge from the eye, which can, in mild cases, resolve independently. However, if it doesn’t resolve on its own, you should seek veterinary help.
When to See Your Vet
If you suspect your cat has a vision problem, it’s best to make an appointment when you first notice signs. Note anything that might be contributing to the issue and explain what you’re concerned about.
Your vet can perform a physical exam to see if there is an underlying health condition causing the tapetum lucidum not to reflect as usual. Your vet might prescribe medications or other treatments depending on the issue.
Do Cats’ Eyes Glow in the Day?
A cat’s eye should never glow in daylight hours. If you are snapping a photo of them, you might notice that the image in the picture reflects the light. That is perfectly normal. However, if you see a cat’s eyes reflecting in the daytime, it is not a normal occurrence.
Conclusion
Now, you can tell your friends that a cat’s eyes glow due to the tapetum lucidum. This feature is not apparent during daylight hours but might be seen in a camera flash. The tapetum lucidum helps your crepuscular kitty see better at dawn and dusk and is designed for survival and skill.
This trait has helped cats, raccoons, possums, and other crepuscular or nocturnal animals navigate low-light settings.
Featured Image Credit: Maslowski Marcin, Shutterstock
