Look into your cat’s eyes. What color are they? The vast majority of adult cat eye colors exist on a spectrum ranging from green, gold and yellow on one side to orange, copper, and brown on the other, with a host of variations and shades between. But what about cats with blue eyes? All kittens are born with nominally blue eyes, and some cats retain this apparent hue throughout life. Why do I qualify a color with words like “nominally” and “apparent”? And when do kittens’ eyes change color and why?
The range of blues that we see observe in cat eyes are a result of refracted light, rather than a function of pigmentation. While we perceive this color of cat eye as blue, it is not a color in itself, but a lack of color combined with a refraction of light. What produces other eye colors in cats is the degree of transparency of the outer eye along with the available pigment in a cat’s iris. Let’s answer, “When do kittens’ eyes change color,” and provide some insight into the how and why of kittens’ eyes changing color.
Kittens’ eyes: What to know about the first month
The first step to answering, “When do kittens’ eyes change color?” is to know that their eyes aren’t even open at birth. Upon exiting the womb and entering the whelping box, a newborn kitten‘s eyes are sealed shut and functionally useless. Like their coatless bodies and closed ears, a kitten’s eyes are not fully developed at birth. The only senses that work straight out of the gate are those of touch and smell. With mother’s assistance and protection, a kitten is able to eat and sleep. These activities provide the fuel and raw materials for growth across the board, including preparing the eyes for sight.
Every kitten develops at a different pace, but typically, a kitten’s eyes are sufficiently mature to open during the second week of life, anywhere from 7-14 days after birth. Once the eyelids begin separating, they may take two or three days to fully open. Even then, open doesn’t mean functional. Part of kitten eye maturation is developing the ability to process light and interpret sensory input.
For the first month to five weeks, a kitten can see about as well as Han Solo fresh out of his carbonite prison in Return of the Jedi, when everything appeared as a “light blur.” Also like Han Solo, who stumbled about a bit at first, hand-eye — or paw-eye — coordination is still very likely a work in progress for a kitten. Most kittens will achieve full ocular and visual functionality at some point between weeks 5 and 7.
So, when do kittens’ eyes change color?
During this developmental period, a baby kitten is learning to see, but her eyes will not be fully mature — including assuming their lifelong adult coloration — until she is anywhere from 3-6 months of age. It’s vision first, color second for kittens. For the first several weeks after a kitten’s eyes open, they appear to be blue. This hue is the effect of light refracted off the cornea, the eyeball’s outer transparent covering and the relative thickness of its four layers. As cat eye color matures, our perception of it continues to be affected and influenced by this refracted blue or blue-green outer covering.
So, when do kittens’ eyes change color? By week 6 or 7, a kitten’s eye color begins to change. The iris, the colored part of the eye, contains melanocytes. Once the eye is sufficiently mature, these melanocytes begin producing melanin, pigment that gives the eye its mature adult coloration. How many melanocytes there are and how much melanin they yield determines the final color and its depth or intensity. On the spectrum we mentioned above — green at one end and brown at the other — light green means a cat’s iris has produced the least amount of melanin, and brown the most.
Exceptions: blue-eyed and odd-eyed cats
There are exceptions to answering the question, “When do kittens’ eyes change color?” — including blue-eyed adult cats and cats with heterochromia iridum, or two different-colored eyes. Cats who retain blue eyes into adulthood do so because of low or no melanin production. Examples include colorpoint cats, like the Siamese, and those breeds who developed with the Siamese as a major genetic contributor. Among them:
Like their fascinating coat-color distribution, the blue eyes in colorpoint cats result from a form of partial albinism. In these cats, blue eyes, like limited coat color, is due to limited melanin. Blue-eyed adult cats are also typical of the Ojos Azules, and in shades much deeper and darker than are typically seen among the melanin-deficient colorpoint breeds.
For cats with white coats and some bi-colored cats, blue eyes as adults can be the result of genes that suppress or mask other pigments, rather than a simple lack of them. Where blue eyes in colorpoint cats are a result of a partial albino heritage — the Siamese and its cousins have white coats before their color patches develop — an all-white cat is not necessarily an albino itself. You can distinguish between a white cat and a true albino by the eyes, which range from pale blue to pink. Like the blue, pink is not a color inherent to the eye, but a reflection of blood vessels at the back of the eye.
Can cat eyes change color with age?
Cat eyes are as mysterious and inscrutable to us as the creatures themselves. Ideally constructed for use by nocturnal predators, they are extraordinary organs. They can detect the slightest movements in situations where there is practically no light available. What’s truly remarkable is that when a kitten is born, she is functionally blind, and her eyes grow and develop along along with the rest of the body.
From the moment a kitten is born until he can safely undergo a spay or neuter procedure, a number of developmental changes occur. Since many of us only adopt cats after they’ve been weaned, we completely miss this period of rapid maturation. Eye color change is one of the last processes we can actually observe if the timing is right and if the kitten’s pace of development is slow enough.
Once a cat is physically mature, her eyes should remain a consistent color throughout life. If you notice a dramatic change in eye color in a grown cat, it could signal a number of health issues, ranging from eye infections and uveitis to leukemia and feline immunodeficiency virus. As with any sudden outward change, the best thing to do if you notice such a change is to consult a veterinarian.
Originally published in 2016.
21 thoughts on “When Do Kittens’ Eyes Change Color?”
I see that every article says that kittens are born with blue eyes then start changing at 7 weeks but my cat had a litter of 5 and all there eyes were gray and still gray at 7weeks old it's that normal
Probably too late for this to be of any use to the original poster, but could the greenish hue be due a yellow pigment along with the natural color. That yellow pigment would be bilirubin, which is a sign of liver failure. I would get him to a vet, even if I had to go to a food bank to eat or eat rice and beans for the next few months.
This article was very helpful. A new feral kitty showed up at my doorstep a couple of weeks ago. From its size and bright blue eyes, I guessed 4-5 wks old. Today I noticed its eyes changing color from very bright blue to kind of hazel.
Its behavior has become very playful, trying to engage the other still young kittens. I changed to a kitten kibble for more calories and they share at least 2 big cans of wet food a day, mixed into kibble.
I also know now that when first seen by my neighbor crying its little heart out, Baby still had poor vision. My guess is that Baby’s momma was killed by a vehicle or a wild animal, leaving the kitten alone and very frightened.
So far, littlest is still easily spooked and has kept its distance. The others do too tho one will now eat with me just a couple of feet away. I’m hoping to trap and get them all in to be neutered and perhaps adopted if they can be tamed … based on their behavior, I’d say there’s still a chance. I’ve started trying to play with them with a feather toy; one is very curious.
Their hangout across the street from my house is getting bulldozed, do it’s a good time for them to stay on this side of the street. I’ve put out “Please Slow Down” signs but I’m getting ready to make a few kitty houses and hoping I can keep them safe.
Thanx again for the info.
I don’t see where that phrase is used here, but “touch and go” is a common English
John disliked starting his car on frosty mornings, since its ignition was touch and go.
I don’t see where that phrase is used here, but “touch and go” is a common English expression meaning “unpredictable”
We didn’t know if we’d make it out alive! It was touch and go there, for a while.
“maybe yes, maybe no”
thank for post
A play on words.
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I wish I have a cat.
My cats:
One is a black cat, as kitten she had blue eyes, then they turned light green in few weeks.
My other cat (black and white) had brown eyes (as dark as those of dogs). Her eyes tok lots of time to change. Now she has yellow eyes
My elderly Himalayan’s eye colors have changed from a beautiful blue to a greenish blue with a few brown flakes. He has diabetes in remission. He also seems to have cataracts. Other than being almost 19, he is healthy, and no, I can’t afford a vet. Why did his eyes change color?
Hi there Christina,
Thanks for reaching out! Here is an interesting article on cat eyes:
https://www.catster.com/lifestyle/cat-facts-science-eye-colors
This article provides helpful information on cataracts in cats:
Well, being an adult elderly cat, his eyes turning green could mean he’s ill or not recovering well from an illness…you should take him to the Vet & get him checked out.
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When we first met our cat Micro, he was a six week old little fluff-ball. In the header picture of the four kittens, he looked just like the one on the far right. a Dark Gray with Black “Tiger” stripes. But as he aged, he gradually turned all Black, (with Red highlights in direct sunlight), which our vet said meant he was a Pure Black, as the Red is a defining trait. He has a Light Gray “Soul Patch” on his lower lip, otherwise he’s all Black, although the hair between his ears and his yes seems thinner then the rest of his coat. His skin color around his mouth is a Dark Gray but on his body, it’s White. He will be Seven Years old tomorrow, August First. I understand, according to you folks at Catster that he would be Forty-Four in Human Years. He’s in excellent health. Oh, I named him Micro as, when he was a kitten, he was so soft and small. Also, he and one of his litter were born with an impacted tail, making them look almost like a Manx, but the vet said he wasn’t a True Manx. When he gets a fright, his tail “puffs up” and he looks like a Black Bunny.
What in the world do you mean Touch and go!?!?
I think it means that kittens have to use their sense of touch as they can’t yet use their eyes at that age, to get around. A play on words.
I don’t see where that phrase is used here, but “touch and go” is a common English expression meaning “unpredictable”; “maybe yes, maybe no”. Examples: “John disliked starting his car on frosty mornings, since its ignition was touch and go.” or: “We didn’t know if we’d make it out alive! It was touch and go there, for a while.”