Can Siamese cats have green eyes?

As per the Cat Fanciers’ Association (CFA) breed standard the eye colour of the Siamese cat is always a “deep vivid blue” and that eye colour is the same across all the different Siamese cat colours from seal point through to chocolate point, blue point and lilac point. And it is the same across the cat associations. For example, The International Cat Association (TICA) ‘s breed standard refers to Siamese cat eye color thus: SI/BA – Blue. ‘SI’ means Siamese and ‘BA’ means Balinese (longhaired Siamese).

Traditional Siamese cat with vivid blue eyes sometimes described as Saphire blue eyes
Traditional Siamese cat with vivid blue eyes sometimes described as Saphire blue eyes. Image: MikeB

The answer to the question in the title is a very confident NO. Siamese cats cannot have green eyes. You might see some Siamese cats which are not true, purebred Siamese cats with green eyes but they cannot be formally described as a true Siamese cat in the West.

And that statement is reinforced by the list of reasons for disqualification of a Siamese cat from a cat show competition. One of those reasons is “Eyes other than blue”.

The irises of the eyes of Siamese cats contain only traces of tiny pigment particles. These are particles of melanin. And because there is so little melanin in their eyes due to the cat’s genetics which create the Siamese cat coat, it is the white light which is refracted through the eye which makes them appear blue.

To put it another way, the Siamese cat’s eyes should be a vivid blue and that blue is not caused by blue pigment in the iris of the eyes but the reason stated above. I think that you’ll find many Siamese cats have an eye colour that is not exactly vivid blue because refracted white light doesn’t normally created a vivid colour (please leave a comment if you disagree).

And the reason why when white light is refracted you see blue light is the same reason why the sky is blue. Below is an explanation according to NASA.

Blue light is scattered in all directions by the tiny molecules of air in Earth’s atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves.

That is pretty much all you need to know about the Siamese cat in response to the question in the title.

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White domestic cats often make bad mothers

Deaf white cats
Deaf white cats. Image by MikeB.

The title sounds unfair and biased but it isn’t as it is based in biological fact. The prevalence of deafness in pure white domestic cats varies depending on whether they have two blue eyes (the highest proportion of deaf cats), odd-eye colour or non-blue eyes (least likely to be deaf in both ears). Where the cat has odd-eye colour, if the cat is deaf, it is in the ear on the side of the blue eye (the eye without pigmentation in the iris).

Deaf mothers can’t hear their kittens’ cries for attention and don’t respond as well as they might if they had normal hearing.

The title may be unfair in one way. Cats are very good at compensating for the loss of one of their senses. Deaf white cats improve their watchfulness by using their excellent eyesight to the maximum.

They will also detect vibrations caused by sounds. They cope admirably with their disability.

The deafness caused by the inherited gene – dominant white – which leaves the hair strands without pigment (melanin) causes the inner ears’ cochlea to degenerate a few days after birth. The deterioration is completely irreversible.

For this reason, it is important to not breed from white cats if possible as the dominant white gene is inherited. How do breeders of white cats cope with this disadvantage? Perhaps the percentage of white purebred cats is very low compared to other coat types for this reason. I expect breeders to breed only from hearing white cats (both parents).

A vet or the cat’s owner can carry out a hearing test by making a sound and watching for the response. The sound generation should avoid vibrations in surrounding objects for the reason mentioned above.

On the matter of prevalence of deafness in white cats ChatGPT (AI chat bot) says this:

It is estimated that about 5-10% of white domestic cats are born deaf. This is because the gene that causes the white coat color in cats is often linked to congenital deafness, particularly in cats with blue eyes. However, not all white cats with blue eyes are deaf, and deafness can also occur in cats with other coat colors. It’s important to note that deafness in cats can also be caused by other factors such as aging, injury, and certain diseases. If you suspect that your cat is deaf, it’s best to consult with a veterinarian for a proper diagnosis and advice on how to care for your cat’s specific needs.

Cornell – a respected source states:

Researchers found that only 17 to 22 percent of white cats with non-blue eyes are born deaf. The percentage rises to 40 percent if the cat has one blue eye, while upwards of 65 to 85 percent of all-white cats with both eyes blue are deaf.

Below are a couple of pages on white cats and deafness. There are more articles. Please search.

Why are white cats with blue eyes deaf?

Deafness in cats – causes, diagnosis and management plus dog info. too

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Colour changes in the eyes of an odd-eyed white cat

Ivory is a 10 year old, white, domestic shorthaired cat with odd-eye colour. Her right eye is gold coloured and her left eye is yellow-green coloured. Her owner, Gabriela Carvalho, 28, a nursing student, adopted Ivory from the same rescue centre that she adopted her former cat from, whose name was Luna. Luna died of the feline leukaemia virus.

Ivory has odd eye color and they change in color
Ivory has odd eye color and they change in color. Photo: Caters News Agency.


They live in Calgary, Canada and in the news today is the story that Ivory’s eyes change colour depending upon the weather. The Daily Mail says that the eyes change from bright green and yellow to orange and yellow. The question is whether this is normal. The answer is that it is normal and it happens in people as well.

I have not seen it written about with respect to domestic cats, however, which is why I am writing this article on the subject. Some Internet writers have stated that eye colour can depend upon the mood of the person or animal. This appears to be incorrect and logically it is incorrect but I am open to suggestions from visitors. It is not beyond of possibly that mood can change eye color slightly. Perhaps health might also have an effect but this does no apply to Ivory the cat in question.

Eye colour might change depending upon the ambient light which in turn is dependent upon the weather conditions. And if a cat is indoors the colour temperature of indoor lighting can affect eye colour. The third factor might be objects near the cat which reflect strong colours which in turn alters eye colour subtly.

Blue Cat Eyes
Why kitten eyes are blue. Image: PoC based on a photo in the public domain.

A major influencing factor too is that blue eyes are due to the refraction of light through the eye and not due to pigmentation in the iris of the eye. This immediately allows blue eyes to change colour more easily because if the light source changes the colour temperature it will impact the colour of the eye. As Ivory’s left eye coontains little pigment it is more susceptible to color changes.

Light does have a colour temperature. For example indoor or tungsten light is much warmer than outdoor sunlight which is much bluer. You can see warm artificial light if you have a dimmer switch turned down. Incidentally, blue sky is caused by the same physics i.e. refraction, which causes an eye without pigmentation to be blue.

The reason why ivory’s eyes are a different colour is because she is an all-white cat. This is caused by the dominant white gene. The dominant white gene has an impact on how pigmentation migrates through the embryo when it is developing in the womb. This results in the pigmentation not migrating to one eye but migrating to the other. An all-white cat has fur which contains no pigment. The dominant white gene must suppress the migration of pigment throughout the embryo.

The same gene has an effect on the development of the inner ear because a lot of white cats are deaf. Essentially, the dominant white gene can have quite a dramatic effect on the development of the embryo in terms of the distribution of pigmentation and the effect on the auditory system.

Ivory appear to have been born with teeth problems. She has some incisor teeth but Gabriela tells us that she has very few teeth. This results in her sticking her tongue out sometimes. She also has a unique purr. Gabriela wasn’t intending to adopt but she was struck by Ivory’s adorable appearance when she passed by a window. She asked the shelter whether she could meet Ivory in the “meet and greet” area.

Ivory actually adopted Gabriela because when she met Ivory, “Ivory came out, walked over to me laid right in my lap and started purring, and she purrs loud and like a pigeon”. That’s an example of a cat adopting a person and you can’t resist.

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What causes the range of eye colors in cats?

The total amount of melanin (pigment) in the iris of the eye determines the range of eye colours in cats and in humans. The same principles apply to all animals with a similar eye anatomy.

The pigment ‘melanin’ is produced by cells called melanocytes. The amount of pigment produced and the way that melanocytes produce the pigment and how it is delivered is controlled by genetics. Genetics are complicated. I don’t intend to go over the genetics of eye colour in real detail although I touch in genetics in this article. I can leave thr details to Sarah Hartwell (messybeast.com). She’s the expert.

Sapphire Blue Eyes of Siamese
Sapphire Blue Eyes of Siamese. Collage: PoC

Suffice to say that eye colour in cats shows a huge variation from blue through to brown. These two extremes in eye colour are caused by no pigmentation for blue eyes and a maximum amount of pigmentation for brown eyes. The reason why cat eyes are blue is because of the refraction of daylight through the eye. Blueness in eyes is not caused by a blue pigment but by white light refraction. But deep brown eyes are caused by the full presence of melanin in the iris. In between these two extremes there is green, yellow, gold and copper. I discuss eye colour in more detail on another page which you can access by clicking on this link.

Blue Cat Eyes
Why kitten eyes are blue. Image: PoC based on a photo in the public domain.

The different degrees of melanin or pigmentation in the iris results in the differences in colour when combined with a variation in the degree of refraction of light through the eye and the effect of genes such as the dilution gene. My assessment comes from the fact that melanin is a dark brown colour. It is a single colour. Therefore to obtain the variations in colour from blue through to brown the brown pigmentation needs to be modified by different degrees of refraction and the effect of genes on melanin production. “Refraction” is quite a complicated physical property which you can look up but in essence it occurs when white light passes through one medium to another which causes the light to be split. This happens in the sky when blue light is seen because the white light has been refracted by minute particles in the air. Blue light is always refracted off.

Blue Cat Eyes
Blue Cat Eyes. Original photograph copyright Helmi Flick.

In domestic cats, selective breeding results in the pedigree, purebred cats having striking eye colours. The range of eye colour in cats and people is due to a polygenetic action. “Polygenetic” means more than one gene. Therefore it is a complicated science. My book on cat genetics (Robinson’s Genetics) tells me that “there appears to be no reliable evidence of monogenetic control of eye colour” (i.e. single gene control).

The cat genes for dominant white, Siamese, and blue-eyed albino and the unique aqua eye created in the Tonkinese cat influence eye colour. Also, the brown and dilution genes (i.e. the genes that create a diluted coat color) can have an effect on eye colour. Although the effect is masked by the range of variability seen in eye colour.

Green cat eyes
Green cat eyes. Photo: public domain.

You probably know this but all kittens are born with blue eyes because for the first few months of life eye pigment is being built up to create their adult eye colour. As young kittens don’t have any pigment in their eyes they are blue for the reasons stated above i.e. refraction of white light.

The deep sapphire blue eyes in pointed cats such as the Siamese are “a result of the pigment producing effects of the albinism allele combined with a low inherent amount of pigmentation”.

What color eyes do Burmese cats have?
What color eyes do Burmese cats have?

Odd-eye color is due to the dominant white gene or piebald gene affecting the depositing of melanin in one of the eyes. It prevents the melanin being deposited in the iris which turns the eye blue while the other eye has pigment which is why it is usually yellow.

Complete heterochromia in domestic cats
Complete heterochromia in domestic cats. Credit as per the image.

To conclude and to recap, the cause of the range of eye colours in domestic cats is the cat’s genetics. A cat’s genes are inherited. The genes dictate the production of melanin and the amount of melanin in the iris of the eye dictates the eye’s colour together with the refraction of light.

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Are cats’ eyes more sensitive to light?

Yes, cats’ eyes are more sensitive to light than those of humans. This is why they shine in the dark because of a reflective layer behind the retina which is called the tapetum lucidum – translation: “bright tapestry”. Humans do not have this layer and it allows the cat to capture light more effectively. In fact it makes a cat’s eyes 40 percent more effective than ours at capturing light.

Glowing eyes
Glowing eyes. “Bright tapestry” behind the retina causes this. Photo: public domain.

A cat’s eyesight is generally poor, it is said, although their eyesight is superior to that of humans under subdued light conditions because of the “bright tapestry” mentioned above. It is said that a cat’s eyesight is 20 percent to 30 percent of that of humans. Although this does not take into account the superior effectiveness of a cat’s eyesight at dusk and dawn. However, cats are very good at detecting moving objects. This allows them to hunt more effectively. Also detecting sound with precision to locate prey is a very important aspect of a domestic cat’s life. I believe that close range eyesight is also poor for the domestic cat which is why they rely on their sense of smell under these circumstances.

What colors do cats see?
What colors do cats see?

A domestic cat’s pupils dilate to 3 times the size of ours and can capture up to 6 times more light. They also have a wider field of view.

Cat Field of Vision Compared to Human
Cat Field of Vision Compared to Human. Image: PoC.

Dr Yuki Hattori, Japan’s leading cat doctor, tells us that stationary objects may sometimes be invisible to the domestic cat because of their poor eyesight. They may not see static objects but they are able to compensate because of their acute sense of hearing and high sensitivity to light combined with their eyesight’s wide field of view.

Domestic cat slit pupil
Domestic cat slit pupil. Image: unattributed. Words: PoC.

The domestic cat has a particularly interesting technique to reduce the amount of light impinging upon their retina. Not only does their iris shrink like a panel i.e. the slit-pupil contracts, the eyelid can pass over the eye to further restrict the amount of light entering it. This allows a cat’s eyes to be particularly sensitive to light but not be harmed by bright sunlight.

By now, it is commonplace for people to know that all kittens have blue eyes. It is at about the age of three months when pigment in a cat’s eyes begin to develop giving them blue and green tints. Siamese and Himalayan cats keep their blue eyes right the way through adulthood.

Blue Cat Eyes
Why kitten eyes are blue. Image: PoC based on a photo in the public domain.

The blueness in the eyes of a kitten is thanks to the physical properties of refraction. White light is refracted revealing blue in the same way that when you look into the sky you see a blue sky.

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5 facts about blue-eyed domestic cats

Odd-eyed white Scottish Fold
Odd-eyed white Scottish Fold living in St Petersburg, Russia. Photo: Caters.

People ask the following questions about blue-eyed cats:

  • Are blue-eyed cat deaf?
  • Are blue-eyed cats blind?
  • Are blue-eyed cats rare?
  • Are blue-eyed cats more sensitive to light?
  • Are blue-eyed cats more expensive?

These are my answers:

Blue-eyed cats are often completely white or they have large amounts of white in their fur. The two go together because of their genetic make up. Blue-eyed, white cats are not prone to hereditary blindness and they don’t go blind at an early age. They are no different to other domestic cats.

Inherited deafness (congenital deafness) is the problem with blue-eyed white cats. Research has found that, according to Cornell University College of Veterinary Medicine, 17 to 22 percent of white cats with non-blue eyes are born deaf. But the percentage rises to 40 percent if the cat has one blue eye. If an all-white cat has two blue eyes the percentage born deaf rises to 65 to 85 percent. The deafness can occur in one ear only. If a white cat has odd-eyes meaning one eye is blue and the other is say yellow and if they are deaf as well, their deafness will be on the same side of the head as the blue eye

Feral cat pictures
Odd-eyed feral cat. Photo: by stratman under a CC license.

In a study by George Strain at the School of Veterinary Medicine, Louisiana State University, the prevalence of deafness in white cats with no blue eyes was as stated above by Cornell namely 17 to 22 percent. Perhaps Cornell got the information from Mr Strain’s study or vice versa. Mr Strain’s study was a review of studies as I understand it.

If an all-white cat has two blue eyes 85 percent are born deaf in one ear (unilateral deafness) and 65 percent of born deaf in both ears. If a white cat has one blue eye 40 percent are born with unilateral deafness and 39.1 percent are born with bilateral deafness (both ears).

White Persian with clear blue eyes
White Persian with clear blue eyes. Photo: Helmi Flick.

The book: Robinson’s Genetics for Breeders and Veterinarians, states that “among a group of 240 white cats in which blue eye colour and deafness was recorded, 39 percent had blue eyes and were deaf, 29 percent were blue-eyed with normal hearing, seven percent were gold-eyed and deaf, while 25 were gold-eyed with normal hearing”.

They also confirm that all-eyed cats who were deaf, were deaf on their blue-eyed side. The white fur of an all-white cat is caused by the dominant W gene. It produces blue iris colour and deafness in 60 to 70 percent and in 40 to 50 percent of cats respectively. The authors of this book state that the deafness is gradual and is “due to degeneration of the canal of Corti” (a reference to the sensitive ‘organ of Corti’ which detects pressure impulses that travel along the auditory nerve to the brain). In essence, the hearing structures are affected by this gene causing deafness.

Blue-eyed cats are not particularly rare because all-white cats are not particularly rare either. Neither are blue-eyed cats any more expensive than other cats. The point I’m making is that the eye colour alone does not make the cat more expensive. A blue-eyed cat might be more expensive if the cat as a whole is rare and for example purebred.

Feral cat pictures
by Chriss Pagani under a CC license.

Whether blue-eyed cats are more sensitive to light is another point. I have blue eyes. There is less pigment in the iris of blue-eyed people and cats. This means that more light passes through the pigmented iris as well as the aperture i.e. the pupil. Accordingly, the eyes are more sensitive to light in my view. Certainly, for me, my eyes are more sensitive to sunlight which predisposes me to wearing sunglasses. I am taking a personal view on this from first-hand experience. But in referring to blue eyes being more sensitive to light I do not mean that the blue eyes see better in the dark. I am referring to bright sunlight causing discomfort because of light impacting the retina in a general way.

SOME MORE ON CAT EYES:

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When do kittens’ eyes change colour?

There is physics behind the answer to the question, which may displease some readers and I’ll understand why! By six or seven weeks of age a kitten’s eyes begin to change colour from blue to the colour that their genes dictate that their eyes should be. In human babies the change takes place at 6-8 months of age. I have discussed this before and you may know why kittens’ eyes are blue. It’s because they do not contain pigmentation in the iris and the colour blue is a result of the refraction (scattering) of sunlight through the eye. The physics behind this process is identical to the physics which creates a blue sky.

Blue Cat Eyes
Why kitten eyes are blue. Image: PoC based on a photo in the public domain.

Why the sky is blue

White light from the sun is made up of all the colours of the rainbow. The gases in the atmosphere of the earth scatters this white light. It breaks up the white light by separating blue and violet from the rest of the light. These colours are scattered in every direction which is why we see blue. The other colours of the spectrum pass straight through the atmosphere to our eyes. The reason why blue is scattered is because the wavelength of blue light is the right size to hit and bounce off the molecules of gas in the atmosphere.

Two Blue Eyed Kittens
Two Blue Eyed Kittens

Pigment producing cells – melanocytes

Blue Cat Eyes
Blue Cat Eyes. Original photograph copyright Helmi Flick.

At about seven weeks, the pigment producing cells in the iris, called melanocytes, start creating melanin, which is the pigment that creates the colour in the iris of the eye. As you know, there is a huge range of colours. If an adult cat’s eyes are to be blue the pigmentation is not created or not fully created. The blue color is entirely due to white light refraction throughout the cat’s life. The same applies to humans. People with blue eyes feel the effects of bright sun more than others because their irises are missing pigmentation which blocks the sun’s rays. They should wear sunglasses.

Sometimes the melanocytes do not produce pigment because they are switched off (my terminology) by the presence of a more dominant gene which might be the dominant white gene or the piebald gene (white spotting gene).

Topaz blue feline eyes
Topaz blue feline eyes. Photo in public domain.

Dominant white and white spotting genes

The dominant white gene creates a white cat. The hair strands are devoid of pigment. The eyes are also devoid of pigment which is why they are blue in white cats. Sometimes white cats have odd-eye colour meaning that one eye is coloured (usually a radiant yellow) and the other is not i.e. it is blue. FYI – you may know to that white cats are not infrequently deaf because the gene referred to affects the development of the auditory system in the cat. I’m told that the hearing deficit is due to “degenerative changes in the succule and cochlea” (Robinson’s Genetics) which in turn is due to a lack of migration and viability of the cells from the neural crest during development. Deafness might be bilateral or unilateral (in one or both ears).

Feral cat with sad odd-eyes
Feral cat with sad odd-eyes. Photo in public domain.

The white spotting gene has a similar effect on eye colour which is why you might see a bi-coloured cat with blue eyes or odd-eyes. You won’t see odd-eyes in a tabby cat for instance because this type of cat does not carry the white spotting or piebald gene except perhaps for the Ojos Azules cat.

Eye colour, as mentioned, varies tremendously. The colour may show shades from emerald green to grey-green to gold, from yellow to deep copper or from pale grey to sapphire blue depending upon the cat breed or the individual cat.

Sapphire Blue Eyes of Siamese
Sapphire Blue Eyes of Siamese. Collage: PoC

Sometimes eye colour is controlled by a single gene (monogenic). The blue or bluish colour (sapphire blue) “produced by the genes for dominant white, Siamese, and blue-eyed albino and the unique aqua eye created in the Tonkinese heterozygote” are examples (Robinson’s Genetics for Cat Breeders and Veterinarians Fourth Edition)

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Turkish Angora Mix and Calico Siamese Mix are both sparkling blue-eyed beauties

The blue eyes of Atlas and Trico crackle and sparkle. There is almost a texture in them. I am not sure why these eyes have this ‘texture’ as I have described it. A lack of pigmentation in the iris of eyes makes them blue because of white light refraction. This is why the eyes of kittens are blue. Both for Trico and Atlas the eyes lack pigmentation because Trico is all-white and has the dominant white gene which removes melanin leaving the hair strands and eyes without pigment. Atlas has the piebald or white spotting gene which does the same thing to the eyes and leaves the coat with white sections. Calicos are tortoiseshell-and-white cats. “Calico” is an American term.

I believe that what we are seeing in these eyes is the muscle of the irises. It is a little mystifying but it is also beautiful. The light helps too as the bright light has caused the pupils to become very small which shows us to see more of the iris. Great eyes.

I am reliant upon their owner for his decription of the cats. It is all but impossible to claim that a cat is a Siamese Mix or Turkish Angora Mix unless you know the pedigree. Visually a cat might have the correct appearance but in claiming that a cat is a “Mix” you are claiming that there is some purebred DNA in the cat and you can only know that if you know the pedigree. Great cats though.

Some more about the dominant white gene and the piebald gene

The completely white cat which has two blue eyes and often odd-eye colour is due to a dominant white gene which is symbolised by a W. Visually it is impossible to tell whether other genes are present in the genotype because the all white coat prevents it. In other words the dominant white gene is epistatic to other colour mutants masking the effect of all other colour genes.

The W gene affects both coat and eye colour in various ways. You might know that it is also linked to deafness. The gene, as mentioned, prevents melanin being deposited in the hair shaft. This is because it also stops melanocytes being present in the skin. These are the cells that produce melanin. In kittens there might be a small spot of colour on the head but this disappears at adulthood. The deafness is due to degenerative changes in the cochlea and succule.

The white spotting gene or piebald gene is very common in domestic cats. It can occur in conjunction with any colour coat. The effect may be limited to small tufts of white hair on the breast or belly (tuxedo cat) or it might render a cat almost completely white with the areas of pigment being confined to the tail or to small spots on the head or body. When the white is extensive it is referred to as “high-grade spotting”. The opposite is referred to as “low-grade spotting”.

Medium-grade spotting is the reason why we have bicolour cats found in many breeds and high-grade spotting is a characteristic of the Turkish Van cat, both for purebred, pedigree cats when created by a breeder or street cats in the Van area of Turkey.

Here are some more pages on eyes.

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