An older calico cat relaxing.
An older calico cat relaxing. Photography by krblokhin/Thinkstock.

What Is Your Cat’s Third Eyelid? And What Should You Do If Your Cat’s Third Eyelid Is Showing?


Did you know that cats have not one, not two, but three eyelids? The first two eyelids are similar to ours — one on the top and one on the bottom that meet in the middle of the eye when the lids are closed. The third eyelid, also known as the nictitating membrane, is a retractable membrane located in the inner corner of each eye (closest to the nose).

Closeup of a cat eye.
A cat’s third eyelid acts like a windshield wiper against debris, pollens, dust and more. Photography © Bloodsuker | iStock / Getty Images Plus.

First, What Is Your Cat’s Third Eyelid?

“Most mammals, other than most primates, have third eyelids,” explains Nancy Bromberg VMD, MS, Dipl. ACVO, a board-certified veterinary ophthalmologist at VCA SouthPaws in Fairfax, Virginia. “When an animal blinks, the third eyelid sweeps across the corneas under the eyelids, acting like a windshield wiper to clear debris, pollens, dust, etc. There is also a lacrimal gland at the base of the third eyelid that produces up to 50 percent of the normal tears.” 

Why Don’t You Usually See a Cat’s Third Eyelid?

Usually, you don’t really see a cat’s third eyelid because it’s hidden from view when retracted inside the corner of the eye. Sometimes, you might be able to see the third eyelid if your cat is very relaxed. For instance, if your cat just woke up from a deep sleep or was sedated for a surgical procedure, you might catch a glimpse of the third eyelids of both eyes.

Cat’s Third Eyelid
You don’t usually see your cat’s third eyelid — and if you do, it might indicate an issue. Photography © Creative_Improv | iStock / Getty Images Plus.

When Does Seeing Your Cat’s Third Eyelid Indicate a Problem?

Most often, however, if you can see your cat’s third eyelid, it indicates a problem — either something is wrong with the eye or third eyelid itself, or possibly another health issue might be at hand (often, a sick cat). Many cat eye conditions cause the third eyelid to stick out, including conjunctivitis or pink eye (inflammation of the eye membranes), corneal ulcers (damage to the corneas), glaucoma, uveitis (intraocular inflammation), masses growing on the third eyelid and Horner’s syndrome (a neurological disorder of the eye and facial muscles).

“The gland of the third eyelid sometimes gets inflamed and swollen and everts the third eyelid,” Dr. Bromberg explains. “This is commonly known as ‘cherry eye.’ It interferes with the normal function of the third eyelid and should be surgically repositioned. This condition is most common in the Burmese [cat breed].”

What Should You Do If You See Your Cat’s Third Eyelid?

If you see any part of one or more of your cat’s third eyelids, you should bring her into the veterinarian for an exam. When one third eyelid is showing and the other is not, that eye might be experiencing an issue. If both third eyelids are showing, and if your cat is acting sick, it could be an indication that your cat is ill with something not necessarily related to the eye.

It’s important not to delay seeking veterinary care because a cat who has a visible third eyelid is likely experiencing pain and/or discomfort. “A full ophthalmic examination should be done to check for corneal ulcers, elevated intraocular pressure, uveitis, masses, etc.,” Dr. Bromberg advises. “Once the cause is determined, appropriate treatment is prescribed.”

Top photograph: krblokhin/Thinkstock.

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37 thoughts on “What Is Your Cat’s Third Eyelid? And What Should You Do If Your Cat’s Third Eyelid Is Showing?”

  1. Hi my cat is on antibiotics for a runny stomach.
    His stomach seems to be finally settling but his third eyelids are still showing badly
    should i return him to vet or should it improve by itseld

  2. In one eye my cats third eyelid has been showing, I don’t know what to do because my local vet does not do exams and I’m worried that she could lose her eye vision.

    Do cats third eyelid heal without healing or do I need some eye drops?

  3. Alister i wonder how is your cat or what was the problem back there with the third eyelid? My cat has the same problem, letargyc, not playful and according to the vet he is healthy….

    1. I would suggest taking your question to some sort of veterinarian subreddit. I don't believe they're going to answer your question regarding your cat's problem. And I wouldn't take veterinarian advice from random commenters here. The advice they've already given in the article is good, and basically says take it to the vet.

  4. I recently got 2 kittens from a friend and one of them has the third eye problem in both eyes he is very happy and eats well I’m about to have them fixed and I wonder if he is normal or not we love him either way

    1. Can you tell us HOW they were FIXED?
      What was the reported problem, other than them being VISIBLE?
      And lastly (but usually never LEASTLY), how much did it cost?

      Thanks for any information.

  5. Pingback: What Is Your Cat’s Third Eyelid? And What Should You Do If Your Cat’s Third Eyelid Is Showing? – Growing Social

  6. Pingback: What Is Your Cat’s Third Eyelid? And What Should You Do If Your Cat’s Third Eyelid Is Showing? – 4Pets

  7. I recently got 2 kittens from a friend and one of them has the third eye problem in both eyes he is very happy and eats well I’m about to have them fixed and I wonder if he is normal or not we love him either way

  8. I just took my car in for both eyes showing third eyelid for about a week. He ran bloodwork checked for leukemia. It was negative. My car is indoor/outdoor. So sometime catches field mice or has some cat fights in our neighborhood. Get gave an antibiotic shot and when his bloodwork came back he said his red blood cess were 1\100th off the normal range for anemia. I would have to run more blood to see what’s causing that, if it is Anemia. So I was never given ointment for eye and think he should at least have some to see if it clears. What else could make his two eyes look like that for so long? He eats well and is in and out as usual.

    1. Hi Caroline,

      Thanks for reaching out and sorry to hear you’re dealing with this. Please keep in touch with your vet.

  9. Pingback: Jack, the Stray. – Cats for Adoption in Chattanooga

  10. Are there certain cats whose third eyelids show more than others? We’ve had a shelter cat for about 5 years whose 3rd lids show whenever he is relaxed. He has startlingly large eyes, making him look like an adorable Japanese anime kitty. He also has a curly tail. Pretty sure that’s not related but he is just such a wonderfully weird cat!

  11. Please help. My cat has had third eyelid showing for 5 days. Taken to vets and initially was due to bad allergies (which are cleared now) but the eyelids are still showing and seem to be getting worse. They are almost covering entire eye. We are giving him eyedrops (vet subscribed) but no impact. We have also been back to the vet twice (different vet 3rd time) and they have given him the all clear. Is this normal?

    1. Alistair J McMurdo

      Hi Gen, reading your post with interest. We have an 18 months old ginger Tom and his third eyelids have been showing for a couple of weeks now. Been to the vets, given the all clear even after blood tests for FIV etc.

      He’s still not himself, bit lethargic, just wondered how your cat has come along.

      Keen to hear news whether it’s positive or negative. I need to know what’s going on with our little guy.

      Kind regards

  12. Michelle Crockford

    There is a stray cat I feed with other cats who just recently is showing signs of third eye in both eyes, she doesn’t appear to be ill but know she just gave birth and is at the moment feeding her young. I wouldn’t be able to catch her but I am worried if she is in any danger and if her eyes would go back to normal.

  13. One of my cats once got in a fight and her third eyelid got scratched, in the process. It was hanging loose for several days. I took her to the vet and she had to have antibiotic eye drops in the eye for a couple weeks. After about a month, you couldn’t tell that anything had ever been wrong.

  14. I would like to pay my invoice online with a credit card. Can you tell me what screen I can do this on?

    1. Hi Cynthia,

      Please go to the Contact Us page and select the appropriate party to contact for this:

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