What Is A Cat’s Inner (Third) Eyelid? Causes, Treatment, Prevention And More

There’s no denying that cats are fascinating creatures in numerous aspects.

They have enviably heightened senses and they see the world the way no one else does. Feline eyes are unique not only for each breed, but also for each kitty. They come in different shapes, colors, sizes and placement. Some furballs may even have heterochromia (two different colored eyes). But the one thing all cats have in common is their third eyelid.

The third eyelid is also known as a third eye or the inner eyelid.

Yes, cats do have such a thing. Similarly to us, human beings, felines have two visible eyelids. One of them is located on top of the eye and the other one – on the bottom. However, what humans lack is the third eyelid – a retractable and usually hidden eyelid, which is located in the inner corner of the cat’s eyes, near the nose.

What is the third eyelid?

To put it simply, the third eyelid is an inner eyelid, which usually stays hidden in cats with no eye problems. All kitties have it, regardless of their age, breed or gender.

As Ernest Ward, DVM, points out on the VCA, the third eyelid is a hidden nictitating membrane that’s covered by conjunctiva. Conjunctiva is a type of membrane, which also covers your cat’s eyeballs and also lines its upper and lower eyelids.

Why do cats have a third eyelid?

This pale pink membrane plays a key role in cat eye care. For the sake of simplifying things, it’s basically an additional protective eyelid, similar to the other two.

I’ll spare you the scientific terminology. Simply put, the inner eyelid is large enough to cover your kitty’s entire cornea and it has a similar function to a car’s windshield wipers. In other words, it wipes off any dirt, dust and other foreign bodies that could irritate your cat’s eye and potentially cause complications for your cat’s overall eye health.

Now, all of this doesn’t mean your pet’s eyes are invincible just because they’re protected by the invisible third eyelid. On the contrary! Cats can suffer from several different types of eye infections and other vision-related problems. And when the inner eyelid is showing, that usually indicates a problem.

Why is my cat’s third eyelid showing?

Seeing a cat’s inner eyelid is stressful and even scary for some pet parents. It’s an unnatural sight, especially if the eyelid is infected. Red, swollen and oozy eyelids mean your cat requires emergency vet help.

There are various reasons as to why the third eye could be showing. The most common are:

  • Conjunctivitis
  • Eye injuries
  • Foreign objects stuck in the eyes
  • Feline herpesvirus
  • Other upper respiratory issues

Sometimes the causes behind the protruded third eyelid aren’t alarming, such as a mild eye injury caused by fights with other cats or something else.

And in other cases it’s possible for your cat to have a visible third eyelid due to its genetic heritage. Breeds like the Burmese often have this trait. It not only looks unsightly, but it’s also uncomfortable for the kitty. In other words, regardless of the reason as to why the third eyelid is showing, the cat needs a vet’s check-up.

Depending on the cause of the problem the vet might prescribe drugs, ointments or even eye surgery. Just like it is with human beings, eyes are among the most essential organs for a feline furball. So if your pet needs to visit the doctor, don’t put it off for long.


Unfortunately, there is no ultimate treatment guide for the problem simply because there isn’t just one health problem that could be causing the third eyelid to become visible. However, there are some things, which you can do to ease your pet’s pain.

Here’s what to do if your cat’s third eyelid is showing:

  • Clean the area. Carefully wipe the eye area with cat wipes – not with the first antibacterial ointments you see in your own first aid kit. Use lukewarm water, soft cloth and pet-safe antibacterial solution if you can’t get cat wipes right this second.
  • Keep the cat well-hydrated. Cats and kittens don’t have a strong sense of dehydration. It’s of extreme importance for your cat to have a good fluid intake, regardless of the problem’s origin. Use canned food, which is high in moisture, and make sure your pet has constant access to clean, fresh water.
  • Stress-proof your home. Try to make your house or apartment as calm and soothing as possible for the kitty. Respiratory infections and other health conditions worsen when the cat is stressed out. Inform any children and house guests that they need to be quiet and not bother the cat physically or emotionally.
  • Offer comfort. Don’t just rely on your pet’s comfortable cat bed. Speak to it gently, pet it lightly, treat it to its favorite cat food. Your kitty needs to know that you’ll be there during difficult times. You are its pet parent after all.

Additionally, your fluffy friend might require eye drops, ointments, radiotherapy or other types of treatment. If the vet has prescribed any medications and has given you care advice, make sure you’re following everything strictly. Negligence on your behalf can and eventually will only worsen the problem.


Some causes of protruding third eyelids can’t be prevented. If your pet is roaming the outdoors, it can easily get into fights with other cats. Moreover, if it’s genetically prone to this issue, you can’t prevent it from occurring.

The best way to make sure your pet is healthy is to take good care of it.

Use high-quality cat food, don’t leave any chemicals around, don’t let it go outside unsupervised and keep all sharp and fragile objects out of its reach. Don’t ever neglect any signs of pain and discomfort and limit the kitty’s access to rooms with cigarette smoke, air fresheners, and other similar air pollutants.

We can’t follow our cats 24/7, but neglecting your pet’s needs and not paying attention to any signs of physical or mental problems could worsen an undiagnosed condition. The sooner you catch the problem and seek veterinary help, the better. A visible third eyelid isn’t a life-threatening issue, but it might indicate a health complication that could indeed pose a fatal danger to your kitty.

Emily Parker

Emily Parker is the Content Manager at Catological. She's passionate about helping cat parents love their cats better by providing the best information and recommendations about everything you'll need to know about your cat, from kitten to senior years. She believes natural, biologically-appropriate products are best...why wouldn't you provide the best for a member of your family?!