Last Updated: 1 month ago

What does it mean if my cat squinting one eye?

Cats use their eyes as a deeply nuanced method of communication; even squinting one eye can be a way to signal information.

But, unfortunately, it makes it more difficult for us to gauge when our furry friends communicate using their eyes and when there is reason to be concerned.

So, let’s go over all of the reasons for the behavior, along with some tips on when to worry.

When to Worry About Your Cat Squinting One Eye

poor sphynx Cat squinting one eye

There are a couple of reasons that your cat could squint only one eye. The real challenge lies in determining whether it is merely behavioral or indicative of something more serious.

Normal squinting can mean that your cat is in pain, annoyed, or showing affection. However, the communicative form of squinting involves both eyes.

So, when a cat only squints one eye, it is likely a symptom of some underlying health issue. With that in mind, lets us take a closer look at why a cat might squint only one of its eyes.

Primary Reasons A Cat May Squint In One Eye

They are mostly related to the anatomy of a cat’s eye.

Let’s break this down by looking at the different parts of your cat’s eyes and the conditions that can affect them.

I can’t stress this enough: if you even suspect that your cat’s squinting is related to a medical problem, please call your vet.

The Pupil

Russian blue cat squinting one eye

You don’t need a biology degree to know that cat eyes are anatomically different from ours, but let me give you one real quick anyway.

The pupil is the most noticeable difference. Where our pupils function similarly to the aperture ring in a camera lens, cat eyes always dilate by the expansion of the slit pupil. 

When we expose our eyes to bright light, our pupil contracts. Basically, it decreases the lens’s aperture to block out more light. When exposed to bright light, the effect is more that of the slit closing horizontally. 

Should this natural sensitivity to light not occur, it may indicate several potential health concerns that extend to potential neurological dysfunction.

A dysfunction like this can be responsible for the abnormal blinking of just one eye.

If you notice that your cat’s eyes are not responding appropriately to light or dark, you should immediately seek advice from your vet.

The Iris

The area around the pupil is called the iris. Just as with humans, this area is the colored part of the eye.

Your feline friend can have a variety of different colors in their iris. They sometimes even also have heterochromia, where the two eyes are different colors.

If the iris color changes or noticeable veins appear, you should consult your vet. Several underlying conditions can appear as symptoms of discoloration of eye color in cats. 

The sensation and irritation in the eye can cause the cat to blink only the afflicted eye.  

The Cornea

tiger cat squinting one eye

The cornea is the transparent lens found in the eyes of many animals. It may seem like a simple, translucent gell-like structure, but it is an astoundingly complex component in a healthy eye.

The cornea plays a role similar to the focal function of a camera lens. So, small changes in its shape can radically impact the eye’s ability to focus correctly. 

Corneal injuries can be serious. For example, some external force often damages the cornea, such as a scratch during a fight.

In addition, many ailments can have a similar effect, damaging the cornea’s structural integrity.

Another common corneal affliction is called edema. Edema is a condition where the cornea becomes clouded and milky in appearance. While it can occur in younger animals, it is most common in mature mammals. 

If you notice any changes in the eye’s cornea in which your cat squints, it is advisable to seek veterinary advice. Such changes are often a symptom of more serious underlying health problems.


The sclera is the medical term for the white of the eye. Although it is not always serious, small changes in the color of the sclera may indicate health concerns involving liver or heart function.

Other reasons for discoloration in the sclera are commonly associated with nutritional concerns. Often the irritation associated with the discoloration can cause a cat to blink only the affected eye.


The pink membrane that surrounds the rest of the eye is called the conjunctiva. The membrane is susceptible to inflammation. 

Redness and swelling are common signs of inflammation in the conjunctiva.

In addition, it is common for only one eye’s membrane to become inflamed, making the condition a relatively common reason why a cat may squint only one eye. 


The eyelids are arguably the most likely culprit when a cat squints in only one eye. Like the majority of other animals alive today, including many mammals, cats have three eyelids.

Like the conjunctiva, the third eyelid is a membrane. It retracts to the inner corner of the eye near the tear duct.

The more familiar primary eyelids are susceptible to infection and inflammation. The third eyelid is equally susceptible to both. There are many reasons a cat might suffer an infection in its eyelids.

Secondary reasons a cat may squint in one eye

There are various reasons your cat may squint in one eye aside from conditions specific to the anatomy of the eye.

It is often the case that an irritant or injury is responsible and that the damage is not specific to a single part of the cat’s eye.

Let us look at some of the most common secondary reasons a cat may squint in just one eye:

Eye Injury

british shorthair Cat squinting one eye

Injury is a common cause of eye issues in cats. They are mostly solitary and territorial animals. Cats tend to respond to each other in one of two ways. An encounter will often begin with s stand-off.

After taking a good measure of each other, one cat will initiate combat, or both will back away. If things turn violent there, tend to be injuries with a likelihood of permanent damage. 

Domestic cats don’t fight to the death, but they will inflict potentially serious injuries on an opponent to win the fight and assert dominance.

Often such attacks are aimed at the neck and head of the opposing cat. Therefore eye injuries are quite common in cat combat. 

Unfortunately, the damage is often irreparable. The cat’s vision can be impaired or completely lost in the damaged eye. It is best to take the injured cat to the vet and keep the eye disinfected as the wound heals. 

Such an injury will likely lead to a permanent squint in the damaged eye. 

Viral and bacterial infection

kitten squinting one eye

Some infections occur as a result of an exposed wound. Many such infections would not happen in otherwise healthy tissue.

However, there are viruses and bacteria capable of invading and infecting a perfectly healthy eye.

Such infections can cause increased tear production and watery or yellow discharge. Secondary infections can cause thick or sticky discharge.

Humans are familiar with such infections, and our feline friends suffer many similar infectious diseases.

Fortunately, most of these infections can be treated, posing little to no long-term risk if detected and treated early. 

That said, there are a couple of viruses in which the eye infection is only symptomatic of a deeper infection. An example of this is herpesvirus. Because you can not completely eradicate the virus, it will reactivate occasionally. 

When it does, symptomatic infections such as a common eye condition will flare up as well. 

If you suspect your cat may have a viral infection causing it to squint in one or both eyes, you should consult a vet for a diagnosis and treatment plan.

Foreign object

While an irritant, such as dust, can lead to more serious eye infections, it is usually easily remedied. A gentle wipe with a warm, moist cloth usually does the trick.

If your cat is blinking in one eye, with no clear sign of an underlying cause, it is likely the result of a bit of dust or a small hair stuck to the eye.

Do I Need To Visit A Vet For Cats Eye Squinting?

a cat squinting one eye

You can attempt to clean out any irritants with a moist warm cloth. However, should the irritation persist, your cat will need veterinary care.

As we have discussed while looking at the various potential causes for squinting in one eye, it is always best to consult your vet.

It is all the more true should there be any obvious signs that something is amiss.


Cats use their eyes to communicate. Therefore, it is a natural behavior for our feline friends to blink and squint both eyes.

However, cats do not squint in just one eye unless there is an issue with the eye.

Potential causes range from injuries to infections, and in most cases, a visit to the vet is the best way to find out what is wrong and how to address the problem.

Have you seen your cat squinting one eye? What did you do? Let us know in the comments below!


grey cat with an eye infection
Olfa T
Olfa T

Olfa knows how to get things done and has a keen business sense that others admire. She’s always on the go, coming up with new ideas! Her ability to anticipate the needs of her readers and deliver information that they want is what makes CatVills such a success. She loves cuddling her cat Picaciu. He is her inspiration.