Why do cats eyes glow image

Why Do Cats Eyes Glow? – Here’s What Science Says

Do you know, the glowing eyes of the cat were amongst the primary reason for it to be worshipped as a God? Cats have always been considered auspicious by Ancient Egypt’s people for several reasons. They believed cats to have supernatural powers, as they could trap the setting sun’s light and preserve it till the following day. That is a myth. However the real reason behind why do cats eyes glow in the dark is because, like every nocturnal animal, cats’ eyes, too, reflect light. Usally eyes are reflective, but cat eyes come with a special layer that gives it the appearance of ‘glowing in the dark. Let’s know the how do cat eyes work reasons why are cats eyes reflective here.

Reason Behind Why Cats Eyes Glow?

A special structure called ‘tapetum lucidum’ is present in animals, providing the reflective surface for light to bounce through. This unique layer was inherited via evolution to nocturnal animals to see ‘super well at night. The global phenomenon of glowing eyes is also scientifically called the ‘eyeshine’. So how does this phenomenon work? To understand that, we have to know what a retina is. A retina is the layer of cells present in the back of the eyes and is sensitive to light. The retina is made of photoreceptor cells which means these cells are responsible for creating the image of an object by reflection. When light from an object hits the retina, some of these may pass through it while hitting the tapetum lucidum.

When light hits the tapetum lucidum, it reflects visible light. So it increasing the capability of the eyes to see better combined with the reflection from the retina. This phenomenon increases the light available to the photoreceptor cells. It helps kittens with the superpower to see better at night than human beings. But it still does not explain why a cat’s eyes glow – as mentioned, some of the light rays hit the retina, and some hits the tapetum lucidum. Most of the time, light rays bounce back, hitting the back of the eyes, and this causes the eyeshine when these light rays are reflected out of the eyes, giving it the appearance of glowing.

Cats Eyes Vs Human Eyes

There is a huge difference between a cat’s eyes and a human being’s eyes. The reason is the absence of tapetum lucidum in the human eyes. Human beings are not predators. Hence unlike cats, evolution didn’t gift us with the special layer to make us proficient predatory hunters at night. To prove this, you can conduct a simple experiment at home. Flash a torchlight in the eyes of a person at night. You will notice there is no reflection or glowing of any sort. Another experiment to try will be the flash of a camera. This gives the appearance of red-eye in the photographs clicked. The red-eye is not reflected because of tapetum lucidum, but the red color is because of blood vessels in our eyes.

Frequently Ask Questions

What makes a cat’s eye seem to glow?

Cat’s eyes come with a particular layer of cells called the tapetum lucidum, reflecting light. On reflection, this layer causes eyes to glow in the dark.

Why do cat’s eyes glow green in the dark?

Green is not the only color that appears when a cat’s eyes are glowing in the dark. Every cat comes with different eye color, and hence different colors are reflected. As green is the most common eye color in cats, we often see a green glow in the dark.

Why don’t my cat’s eyes glow in the dark?

Almost every nocturnal animal comes with the ability of glowing eyes in the dark. In case you fail to notice a glow in the eyes of your cat at night, that may be because your cat is not able to see properly. A lack of glow suggests that not enough light reaches the retina of your cat’s eyes and tapetum lucidum.

What colors do cat eyes glow in the dark?

The most common color to be reflected by a cat’s eyes is the green colour, but other than that we can also notice bright yellow colour in the case of Siamese twin cats. The intensity of the glow may vary depending upon your cat’s eyesight.

Can a human have cat eyes?

This is a syndrome present in a few human beings because of the chromosomes they are born with. Only 1 out of 50,000 people are born with this syndrome, and it gives a human eye the appearance of a cat’s eyes but it still does not glow at night.

What is the function of tapetum lucidum?

The tapetum lucidum serves as the second layer of photoreceptor cells for light to reflect and create a high-resolution image for nocturnal animals. It helps enhance the visual power of predatory animals to hunt at night.


Cats are a creature of mystery, but assuming supernatural powers because of glowing eyes can be unnecessary. Every phenomenon can be explained scientifically. The reason behind why do animals eyes glow in the dark, is evolution and the presence of an extra layer of cells. Next time when you see a bright pair of eyes lurking in the alley do not be surprised as it’s only a harmless cat out for a hunt.