Cat eye color is important to breeders of purebred cats. The colour is referred to in the breed standards4 and is sometimes linked to coat colour. An example of linkage might be silver tabby cats that are often required to have green eyes3. For instance, the breed standard for the Russian Blue is described as:
“Vivid green. Set rather wide apart, almond in shape, not small and deep set”…1
 | Russian Blue Cat |
“EARS: strikingly large, pointed, wide at base; continuing the lines of the wedge….Eye color: deep vivid blue”
The above applies to the Modern Siamese cat. We know that Siamese cats have blue eyes.
Left: This is not a Modern Siamese but a Traditional Siamese.The eye color is a deep vivid blue in line with the CFA eye color standard for the Modern Siamese cat.
Although, I suspect that the color balance of this photo favours blue! Photo: Juergen Kurlvink
In fact the only eye colour that is naturally linked to coat colour is blue. Blue eyes are caused by “forms of albinism” 3 that results in lack of pigmentation in the iris of the eye and coat. The iris is the part of the eye that we see that produces the colour of the eye. It controls the amount of light that the eye lets in.
Eye colour in cats in more apparent than it is for humans because their eyes are larger in relation to their heads. A cat’s eyes are unusually large. If human eyes were of comparable size in relation to the head, they’d be several inches in diameter, it is said. The cat’s large eyes give them a baby-like appearance.
Apparently green eyes or eyes with shades of green have become common in random bred cats (moggies).
Kittens are often born with blue eyes which change colour when they become adults. This is because eyes without pigment in the iris look blue due to scattered light. When pigmentation develops the eye takes on a color.
There is a wide range of eye colours from copper at one end of the spectrum to blue at the other. There are also odd eyed cats. This condition is caused by the gene that produces coats that are either totally white (dominant white gene) or spotted white (white spotting gene or piebald gene).
Here is a range of cat eye color:
 | Copper |
 | Copper-orange |
 | Orange |
 | Orange |
 | Orange-yellow |
 | Yellow-hazel |
 | Hazel |
 | Green |
 | Aqua-blue |
 | Blue |
 | Blue |
 | Odd-eyed Cat Photo: by sly06 (Flickr) |
***All the photos are thumbnails – please click on them to see large format versions. They are also all (unless stated otherwise) copyright Helmi Flick. Please respect copyright. Thanks
As mentioned, cat eye color is formed in the smooth muscle cells of the iris. The iris creates the pupil, the aperture in the center of the eye that lets the light in to the retina in a controlled manner.It is the amount and intensity of pigmentation that is in the front and rear of the iris that determines cat eye color.
Sectoral heterochromia
Odd-eye color is called complete heterochromia. It is caused by the dominant white gene. A rarer form is sectoral heterochromia when each eye has two colors: blue (or no color) and orange or yellow. Blue is caused by light refraction not pigmentation.
Some other instances where eye color is specified by the breed standard would be:
Nebelung: Color: Green with yellow/green mixture allowed. In kittens, changing from yellow to green. Should show green halo around pupil by 8 months. As vividly green as possible at maturity, which could be at 2 years or more. The more richness and depth of color, the better (TICA breed standard verbatim).
Turkish Van: Color is amber, blue or odd eyed.…Allow for faded eye color and greenish cast to amber eyes in cats over 18 months of age (TICA breed standard verbatim extracts).
There are many more. Start here for articles on all the cat breeds.
There is one last point to make. The true albino cat as opposed to the all-white cat (carrying the dominant white gene) has no pigment in the eye and therefore it looks pink:
Cat eye color – Associated pages:
- Cat Eyes
- Are Cats Color Blind?
- Cat Anatomy
- Cat Eye Colors from VG (Valley Girl)
- White fur – deaf cat
Cat eye color – Notes:
1. russianblue.org.uk – Russian Blue Breeders Association
2.cfainc.org/breeds/standards/siamese.pdf
3. The Encyclopedia Of The Cat by Dr Bruce Fogle
4. Breed standards are the guidelines issued by each cat association as to the requirements regarding the appearance of individual registered breeds.
He’s going to be an odd-eyed cat. Is he deaf or partially deaf? You probably know that with odd eyes and white coats you can get deafness:
http://cat-chitchat.pictures-of-cats.org/2011/10/what-percentage-of-cats-with-blue-eyes.html
Here is a page on odd eyes:
http://cat-chitchat.pictures-of-cats.org/2008/02/odd-eyed-cats.html
I’ll presume but could be wrong that he is all-white.
This is a page on eye color development:
https://pictures-of-cats.org/Why-are-kittens-eyes-blue.html
You ask:
I am not sure of the answer to be honest. It is just part of the development of color in the eye.
Thanks for visiting and asking.
Can someone help me understand eyes transformations in kittens? Does the iris change over all, slowly fading to its permanent color? Or does the change start at the outside of the pupil and just grow more and more towards the iris edge? My 10 week old kitten has two completely different colors in his eyes. Will the green continue to spread or will he have dichronic eyes? I got him 2 weeks ago and the green was just as noticeable but has darkened some these last two weeks. The size of the green has not grown tho.
I can’t answer your question from the top of my head except to say this seems to be okay and perhaps linked to age. The eyes of elderly cats do change color and go darker. That is the limit of my personal experience.
…but a good book on cat health states:
Color change: a change in color of the eye may indicate the cancer known as melanoma….
I don’t believe that is relevant in this instance as the change would appear to be permanent whereas for your cat it is temporary. My gut feeling is that it is nothing to be concerned about but to observe it.
Thanks for visiting and commenting. My best wishes to your elderly cat.
My cat is 17 yrs old and for the last month, she is on thyroid medication. Prior to this however, one of her eyes turns a dark copper color, which tends to disappear after a couple of days. She is all black, has a beautiful coat, and her eyes are yellow/green. As of her last check up/blood work 3 wks ago, she has healthy kidneys and liver. Should I be concerned about this change in eye color? I neglected to mention it to the vet when she was last examined.
Thanks for sharing Monica. Here is a lighter version of your photo. I agree the color is a sort of dark hazel. Nothing quite matches in the list I presented. The coat color/type appears to slightly diluted tortoiseshell. Interesting looking cat.
Cat eyes will be stable after about 6-8 weeks of age, simply becoming more or less vivid after that point in time. As for predictable colors for the litter, that is even more difficult as a litter can have more than one father (hence how you end up with short haired color point cats and long haired black cats and medium haired tabbies all in one litter, for example). As mom isn’t purebred, there’s no clue what recessives she could be carrying, so it would be hard even if we knew some info about daddy(ies)