Yes, a cat’s eyes can change color when they are sick, and it’s one of the more visible warning signs of several serious conditions. The changes range from subtle shifts in iris pigmentation to dramatic clouding, reddening, or yellowing of the eye. Because cats are notoriously good at hiding pain and illness, a visible change in the eyes is often one of the first clues an owner notices.
Not every color change signals a problem, though. Understanding what’s normal and what’s not can help you decide how urgently your cat needs attention.
Normal Eye Color Changes in Kittens
All kittens are born with blue eyes. Between 6 and 10 weeks of age, their eyes begin transitioning to their permanent adult color, which could be green, gold, amber, copper, or remain blue in certain breeds. This process is gradual and completely normal. By about 3 to 4 months, most kittens have their final eye color, though some continue to deepen in shade for up to a year.
If your adult cat’s eyes suddenly look different, that’s a separate matter entirely.
Uveitis: Inflammation Inside the Eye
One of the most common illness-related causes of eye color change in cats is uveitis, which is inflammation of the structures inside the eye. It can make the iris look different in color, cause the eye to appear red or cloudy, or give the normally clear fluid inside the eye a hazy, murky look.
Uveitis produces a wide range of visible signs: redness in the white of the eye, a constricted pupil, swelling of the iris, cloudiness across the surface of the eye, and sometimes visible blood or pus pooling in the front chamber of the eye. Cats with uveitis typically squint, tear excessively, and avoid bright light.
What makes uveitis especially important is that it’s rarely a standalone problem. It’s usually driven by an underlying systemic disease. The most common infectious causes include feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP), toxoplasmosis, and bartonella infection. It can also result from cancer within the eye or, less commonly, from trauma. When a vet sees uveitis, they typically want to investigate what’s going on in the rest of the body, not just the eye.
Yellowing Eyes and Jaundice
If the whites of your cat’s eyes take on a yellow tint, that’s jaundice. Since most of a cat’s skin is covered in fur, the eyes, gums, and inner ear flaps are the easiest places to spot it. Jaundice reflects a buildup of bilirubin in the body, which happens for one of three reasons: red blood cells are being destroyed too quickly, the liver is damaged or diseased, or the bile duct is blocked.
Cats with a blocked bile duct tend to be extremely jaundiced, with obvious yellowing not just in the eyes but across the skin. Liver disease and certain blood disorders produce more gradual yellowing. In all cases, jaundice signals something serious that needs prompt diagnosis.
Dark Spots on the Iris
Flat, dark spots appearing on your cat’s iris are among the trickiest color changes to evaluate. They can be completely harmless or an early sign of cancer.
Benign iris freckles and nevi are small clusters of normal pigment cells on the surface of the iris. They tend to have sharp borders, stay flat, and remain superficial. These spots can be present from birth or develop with age, and many cats accumulate more of them as they get older.
Diffuse iris melanoma, on the other hand, is the most common primary eye tumor in cats. It typically starts as one or more dark patches that gradually expand and merge over time. The pigmented areas may look slightly raised with a velvety texture. As the tumor progresses, it can invade deeper into the iris, distort the shape of the pupil, and affect how the pupil responds to light. Advanced cases can lead to glaucoma from tumor cells clogging the eye’s drainage system. Metastasis rates for feline diffuse iris melanoma range from 19% to 63% in published studies, which is why veterinarians take progressive iris darkening seriously.
The key distinction is progression. A freckle that stays the same size for years is likely benign. Dark patches that are growing, spreading, or changing the shape of the pupil warrant veterinary evaluation. Vets typically document these spots with photographs over time to track any changes.
Cloudy or Hazy Eyes
A bluish-white haze over one or both eyes can indicate several different conditions. In older cats, a common and harmless cause is nuclear sclerosis, where the center of the lens becomes denser with age and takes on a slightly cloudy appearance. Unlike cataracts, nuclear sclerosis does not cause significant vision loss.
True cataracts, where the lens becomes opaque, are less common in cats than in dogs but do occur. A mature cataract affects the entire lens and significantly impairs vision. Cataracts can develop secondary to chronic inflammation, diabetes, or other metabolic issues.
Glaucoma, caused by increased pressure inside the eye, can also give the cornea a cloudy or bluish appearance, though cats tend to show this less dramatically than dogs at similar pressure levels. Other signs of glaucoma include a dilated pupil that doesn’t respond normally to light and, in advanced cases, visible enlargement of the eyeball.
Blood in the Eye
Hyphema, or blood collecting in the front chamber of the eye, is hard to miss. The eye may look partially or completely red, and in some cases the blood clots and gives the eye a dark blue-black appearance. The amount of blood can range from a thin layer settling at the bottom of the eye to the entire chamber being filled.
Trauma is one of the most frequent causes, including car accidents, falls, animal fights, and blunt injuries. But hyphema can also result from severe infections, blood clotting disorders, high blood pressure, or tumors. When the blood appears clotted, trauma or infection is more likely. Unclotted blood that persists suggests a bleeding disorder may be involved.
Changes in Pupil Size and Shape
Some illnesses don’t change the color of the eye itself but alter how the eye looks by affecting the pupil. Horner’s syndrome, caused by damage to a specific nerve pathway, produces a characteristic set of signs: one pupil becomes noticeably smaller than the other, the affected eye appears slightly sunken, the upper eyelid droops, and the third eyelid (a membrane cats have in the inner corner of the eye) slides partway across the eye. In cats, the third eyelid protrusion can be especially prominent because the eyelid contains smooth muscle fibers controlled by the affected nerve.
The difference in pupil size is most obvious in dim lighting, when the normal eye dilates but the affected eye can’t. Horner’s syndrome can result from middle ear infections, chest tumors, neck injuries, or sometimes has no identifiable cause.
Redness and Discharge
Conjunctivitis, or inflammation of the membrane lining the eyelids, is one of the most common eye problems in cats. It makes the eye look pink or red, often with watery or thick discharge. One of the most frequent causes is cat flu (feline upper respiratory infection), though bacteria, allergens, and physical irritants like grit or dust can also trigger it.
While conjunctivitis itself doesn’t change the iris color, it can dramatically change how the eye looks overall, and owners often describe it as the eye “changing color” because the redness and swelling obscure the normal appearance.
When Eye Changes Need Urgent Attention
Any sudden change in the appearance of your cat’s eyes warrants a veterinary visit. Some situations are more urgent than others. Visible blood inside the eye, sudden cloudiness or haziness, obvious pain (squinting, pawing at the eye, excessive tearing), a sudden difference in pupil size between the two eyes, or yellowing of the whites of the eyes all call for prompt evaluation. A cat that seems suddenly unable to see, bumping into furniture or misjudging jumps, needs same-day attention.
Gradual changes like slowly expanding dark spots on the iris still need to be checked, but you typically have time to schedule a regular appointment and begin monitoring. The critical thing is not to dismiss color changes as cosmetic. In cats, the eyes are often a window into systemic health problems that aren’t yet showing other symptoms.