People used to think that cats were colour-blind and could see only in black and white. This belief came about because cats did not and apparently could not be taught to respond to other colours
Recently, however, cats have been taught to distinguish between colours : red from green, red from blue, red from grey, green from blue, green from grey, blue from grey, yellow from blue, and yellow from grey. cats don’t seem to think to much of this ability and, in fact, don’t need to know one colour from another. Cat’s eyes are highly developed in other areas, accommodating skills that are important to cats
For example,cat’s eyes are very well adapted to dim light. Like in humans, cats’ retinas cantain two kinds of recetor cells: rods and cones. Rods aid night vision and sensitivity to low light, and cones aid resolution. Cats eyes contain more rods and fewer cones than those of humans. Therefore they see better at night, but the image is somewhat fuzzy.
Cats eyes also contain a special light-conserving mechanism called the tapetum lucidum, which reflects any lights not absorbed as it passes through the retina. As a result ,the retina gets a second chance to receive the light, aiding cats night vision even more. This reflective mechanism is also what is responsible for cats eyes glowing in the dark when light hits them at certain angels.
The night glow occurs when the pupil is at its widest, in very dim light. But cats pupils protect the eyes from very bright light, too, by contracting to just narrow slits. When the pupils are contracted to their maximum, the close completely in the middle and are still open to the size of pinholes at the tops and bottoms. Light that is too bright to be handled by the narrowing of the pupils can be accommodated by cats shutting their eyes.
Cats also have binocular vision, meaning that parts of the field of each eye overlap. This skill is necessary for three-dimensional vision, which is necessary for hunting animals. Without it, cats could not judge distance, depth or size. Because binocular vision is not as pronounced in some breeds, such as the Siamese, they are not as successful hunters. Cats eyes are also very sensitive to movements, another plus for felines that hunt.
but, even with all these ocular abilities, a cat is not born with the ability to use them. Kittens are born blind and, at 8 to 20 days, when the eyes open, they have to “learn” how to handle all the stimuli coming in through their eyes. They are unlikely to master the organs until they are approximately 12 weeks old
That is also about the time their eyes change to their permanent colour. The most common shades are orange, yellow, green and blue . Many white cats with blue eyes are born deaf, and in cats with one blue eye, the corresponding ear is partially deaf. No matter what the colour of the iris, with rare exception the pupil is usually black