What color are cat's eyes?

What color are cat's eyes? A wide variety of colors is the answer although kittens before the age of about 7 weeks have blue eyes. The gene that makes a cat white also affects eye color and makes them blue. Sometimes it will cause one eye to be blue and the other yellow for instance. This is odd-eye color and the preferred appearance of the Turkish Angora cat breed in Turkey.

The dominant white gene (W) causing a cat to have completely white fur also affects the cat's hearing causing deafness sometimes. The piebald gene (S) or white spotting gene can also affect eye color and hearing. This is because both these genes affect the production of pigmentation, eumelanin in the fur and eyes.

The breed standards of cat breeds sometimes allows any color of eye or it might limit the color of the eyes that are acceptable to the cat association. See for example the breed standard for the Turkish Angora.

Cat eye color is determined by the pigment in the smooth muscle cells of the iris, the disk around the aperture called the pupil in the middle of the eye. The amount of pigment deposited determines the intensity of color.

Blue eyes are caused by an optical effect. The front layer of the iris lacks pigmentation but there is pigment in the rear layer of the iris. The light hitting the iris is reflected back blue. The amount of eumelanin on the rear layer dictates the density of the blue.

The green eye is due to a combination of the rear layer of the iris reflecting blue and the pigment in the front layer reflecting yellow. The depth of the green color depends on the amount of pigment in the front layer of the iris.

See a range of cat eye colors.

Source for iris color: Legacy of the Cat by Gloria Stephens ISBN 0-8118-2910-3