Feline eyes and vision
Round and lustrous, oval or almond-shaped, Oriental and slanting towards the outer edge of the ears, are descriptions often used when describing the beautiful eyes of a pet that has been enjoying a special niche in human society for quite some time. Cats have been glorified in poems, can be found on postcards and paintings, appear on stationary and clothing, and have been recorded in history, as far back as the days of the ancient Egyptians.
It is a well known fact that cats see the world differently than their human companions. People’s eyes work best in day light, while those of a cat, predominantly nocturnal and crepuscular in activity, must function well in extremely low light condition. This means that cat eyes have some sort of night vision and are able to function adequately in roughly one-sixth of the light needed for human vision.
A cat’s eye is designed to capture even the slightest movement, which is useful for hunting, and like humans, their vision is binocular which helps in judging distance. Their eye color is genetically related to their coat color, and can be blue, green, gold or copper. Some have “odd eyes,” which means the feline has one blue eye and one green or gold.
Cats rely on their eyes to hunt, and losing their vision can be devastating. Like us, cats can get sick and their eyes can become infected or inflamed. They can develop tumors or Horner's syndrome, a neurologic disorder caused by some type of injury to, or lesion of, the nerves. In other cases their central nervous system can get injured, or the pupils are prone to develop spasms.
Cats have an inner, third eyelid, called a nictating membrane. It serves to protect the eye from dryness and/or damage and will partially close when the cat is sick. If that happens, and it is coinciding with some other symptoms, seek medical attention immediately. If caught in time, many conditions can be treated easily, and blindness can be prevented.