You’re walking along a lonely alley at night. Ahead, you see a startling pair of shining, disembodied eyes out of the dark. As you get close, you found out that they were just the eyes of your neighbor’s cat.
You might think that the cat is playing some fun tricks on you but, truth to be told, the glow in their eyes in darkness is one eerie aspect of their fascinating feline structure. Cats have an anatomical feature in their eyes that humans don’t.
Cats’ eyes have a glossy area called tapetum lucidum. It is a thin layer of reflective cells situated at the back of the retina or the field behind our eyeballs that collects light. Other animals, such as deers, dogs, and horses, have tapetum lucidum, though this functionality is more noticeable in the eyes of cats.
You will only a cat’s shining eyes if the area is dim and not when the room is in total darkness. The tapetum lucidum needs at least a little amount of light it can reflect, or else, it won’t be able to function.
But, why do cats have tapetum lucidum? Well, this stems from the fact that cats are generally a night animal. The said functionality boost their vision at night by mirroring back low light to the retina, providing the cat’s eyes a second look or chance to collect visual data and send it to the brain. With that, cats’ eyes are more sensitive to humans eyes, allowing them to pass dark rooms or area without bumping into something or knocking things over.
The glow on the eyes of most cats appears to be bright green. However, Siamese cats tend to show a bright yellow glow. The color of the glow differs. It depends on the animal and the amount of riboflavin and zinc present on the reflective cells found in the tapetum lucidum.
Riboflavin is an amino acid, while zinc is a metal, which both serve as pigment agents. The glow color of the eyes then varies from different breeds, taking composition and density of the reflective cells into account. Ferrets and dogs, for instance, have zinc. Cats, on the other hand, have riboflavin.
Aside from the composition, the age and the coat color may also affect the glow color from their eyes. As the animal gets older, the reflectivity of the tapetum lucidum decreases. Thus, lessening the ability of the eyes to reflect the light.
Meanwhile, cats possessing white coats partnered with bluish eyes tend to provide a red eyeshine in dimmer places. The red glow is caused by the blood vessels in their eyes, mirroring the light.
Generally, the cat’s tapeta lucida remains protected behind the eyes. If you have a cat, there’s nothing to worry about them too much.
What you need to be watchful for is your cat’s taurine level. Deficiency in the said amino acid, usually found on fish and meat, may lead to the deterioration of the tapeta lucida. If you’re feeding your cat with commercial feline food, it often contains enough taurine for his eye health. However, if you’re feeding your cat at home, it’s better to consult a veterinarian to ensure that you’re providing enough nutrients in his meal and keep his tapeta lucidum functioning at its best.
More Readings:
- Cat (Wikipedia)
- Tapetum Lucidum (Wikipedia)