Every cat owner has probably noticed that their pet’s pupils narrow and look like slits in daylight. And when it gets dark, the pupils dilate and the eyes begin to glisten mysteriously. It should be noted immediately that a cat’s eyes do not glow in total darkness. But if there is some light at dusk, the pet’s eyes instantly turn green or yellow. Why does this happen?
The ability to see at dusk, as well as to calculate the distance to an object and to observe any movement, is a very important “skill” for an animal that hunts in the dark. It is certainly an essential skill for a predator, which must be able not only to track its prey but also to make a precise leap.
Tapetum lucidum layer and its characteristics
Cats’ eyes have certain anatomical features that humans do not. They can see at night thanks to a certain layer of light-reflecting lamellae called the tapetum lucidum (Latin: tapetum), located behind the light-sensitive retina, at the back of the eyeball.
Cats, dogs, deer and other nocturnal animals have good night vision because light entering their eyes immediately reaches this special layer behind the retina, almost without touching the photoreceptors. The light then passes through the animal’s eye again after being reflected from the special layer. In this way, animals receive more photons from the objects they are looking at.
It is thanks to the tapetum lucidum layer that cats’ eyes are six times more sensitive to light, unlike human eyes. The presence of a thin layer of reflective foliage allows these animals to move without problems in darkened rooms, night streets, fields and forests.
The glowing eyes of a cat can be seen in low, dim light. They will not glow in total darkness because the thin layer needs at least a little light to reflect it.
The eyes of many cats glow green in the dark Light. Some cats may have different shades of light emitted by the visual organ. For example, the eyes of Siamese cats have a yellowish glow. In Siamese-bred breeds, the eye glow may be brighter. But sometimes a cat’s eyes shine differently. This means that they have different levels of pigmentation.
Nature has made sure that the tapetum lucidum layer is reliably protected – it is located behind the retina. However, this part of a pet’s visual apparatus can also be problematic. This happens when the pet’s diet is deficient in taurine and certain amino acids, which are present in meat and fish. If the cat eats little or nothing of these products, damage to the thin layer of reflective foliage is possible. In this case, the cat will be much less able to navigate in the dark. Its eyes will glow dimly or not at all.