Yes, nearly all kittens are born with blue eyes, and that first blue is not permanent pigment. A kitten’s eyelids stay fused shut until roughly 7 to 14 days of age, and when they first open, the iris has no melanin in it yet, so light scatters off the clear tissue and reads as blue. That is a structural effect, not a pigment, the same reason the sky looks blue. Over the next 3 to 6 weeks, melanocytes in the iris begin producing melanin, and the true adult color (green, gold, yellow, copper, brown, or in some cats permanently blue) usually shows by 6 to 8 weeks and is fully stable by 3 to 4 months of age, within the neonatal development window described by the Merck Veterinary Manual (last reviewed 2022).
| Age | Eye status | What is happening |
|---|---|---|
| Birth to day 7 | Eyes closed | The eyelids are still fused shut, so the eyes are not visible yet. |
| Day 7 to 14 | Eyes open, iris uniformly blue | No melanin has been deposited in the iris yet, so light scatters off the clear tissue and reads blue. |
| Week 3 to 6 | Color begins to shift | Melanocytes in the iris start depositing melanin, and flecks of the adult color appear. |
| Week 6 to 8 | Adult color largely visible | Green, gold, yellow, copper, or brown takes hold, depending on how much melanin the iris carries. |
| Month 3 to 4 | Adult eye color stable | Eyes stay blue only when genetics dictate it, as in Siamese cats or cats carrying the dominant white gene. |
Evidence-reviewed, not hands-on tested.
When do kittens open their eyes?
Kittens are born with their eyelids fused shut, and like any baby mammal they need time to mature. Those lids separate at roughly 7 to 14 days old, which is why the familiar rule of thumb of around 10 days sits right in the middle of the normal window described by the Merck Veterinary Manual (last reviewed 2022). When you finally get a look at those eyes, they are a hazy blue, and that blue is not the color your cat will keep into adulthood. The iris simply has no pigment in it yet.
When do kitten eyes change color?
The shift starts between about 3 and 6 weeks of age, when melanocytes in the iris begin depositing melanin. Adult color is usually obvious by 6 to 8 weeks and fully stable by 3 to 4 months. Where it lands depends on how much melanin those cells lay down: yellow, green, brown, copper, or blue, with plenty of shades in between. One cat can even end up with two different colored eyes, called heterochromia, which the Cornell Feline Health Center (last reviewed 2018) reports most often in white cats, where the white coat gene keeps pigment from reaching one iris. These traits are set by the cat’s genetics, and eye color is defined tightly enough that breed registries write it into their standards: the Cat Fanciers’ Association Siamese standard calls for deep vivid blue.
Which cats keep blue eyes for life?
With that said, some cats are destined to have blue eyes permanently. The lack of pigment that appears blue is defined by their DNA as well. White cats sometimes have blue eyes that is associated with congenital deafness. In fact, up to 85% of white cats with blue eyes will also suffer from congenital deafness 1. That figure comes from the Cornell Feline Health Center deafness overview, last reviewed 2018. Sometimes the deafness will only affect one ear, so these cats may seem to behave normally. It seems that the gene for blue eyes is also associated with hearing.
Studies have suggested that some cats with permanently blue eyes (in this case, Siamese) have changes in their brains because of the difference that the lack of pigment makes in the way the eye handles light.² That work is Kaas, ILAR Journal, 2005, a peer-reviewed review of how the genes for coat and eye pigment reroute visual wiring in Siamese cats. Who your cat is, the way he hears, sees, and even looks are expressions of his genetic map.
So will my kitten’s eyes stay blue?
Adult eye color is written in the genes, but newborn blue is not the same thing. It works more like an optical illusion. Because the eyes are still developing, the pigment responsible for permanent eye color has not been deposited in the iris yet, so the eyes only appear to be blue. If you love those baby blues, don’t despair. If your kitten is meant to be a Frank Sinatra among cats, like the Siamese (in eyes and voice), it is already written on his genes and all you have to do is wait and see.
- Cornell Feline Health Center. Deafness. Last reviewed 2018. http://www.vet.cornell.edu/fhc/Health_Information/deaf.cfm
- Kaas JH. Serendipity and the Siamese cat: the discovery that genes for coat and eye pigment affect the brain. ILAR J. 2005;46(4):357-63. Review. PubMed PMID: 16179744.
Kitten blue eyes: quick answers
Do all kittens have blue eyes?
Nearly all of them do, at least at first. When a kitten’s eyes open at about 7 to 14 days, the iris has no melanin in it yet, so it scatters light and looks blue. That blue is a structural effect rather than pigment, which is why most cats do not keep it.
At what age do kittens open their eyes?
Usually between 7 and 14 days old. Kittens are born with fused eyelids, and the lids separate during that window, so the old rule of thumb of about 10 days sits right in the middle of normal.
When do kittens’ eyes change color?
Melanin starts appearing in the iris around 3 to 6 weeks, adult color is generally obvious by 6 to 8 weeks, and it is usually stable by 3 to 4 months of age.
Do kittens’ eyes stay blue?
Only when genetics call for it. Siamese cats keep deep blue eyes for life, and so do many cats carrying the dominant white gene. Most other cats settle into green, gold, yellow, copper, or brown. And yes, the Siamese is the same breed with that famously loud voice.
Why does one cat have two different colored eyes?
That is heterochromia. The Cornell Feline Health Center reports it most often in white cats, where the white coat gene keeps pigment from reaching one iris, so that eye stays blue while the other develops normal color. It is the same family of white-coat genetics behind white markings on other cats.
Are blue-eyed white cats always deaf?
No, but the risk is high. The Cornell Feline Health Center reports that up to 85% of white cats with blue eyes have congenital deafness, and sometimes only one ear is affected, so the cat can seem to hear normally.
What eye colors do adult cats end up with?
Green, gold, yellow, copper, brown, or blue, with plenty of shades in between, depending on how much melanin the iris carries. Pedigreed cats are often held to a specific eye color in their written standard. The Cat Fanciers’ Association Siamese standard, for instance, calls for deep vivid blue, which is part of why certain pedigreed breeds look so consistent from cat to cat.