What Is a Third Eyelid in Cats?

by catfood

Did you know that cats have more than just two eyelids on each eye? Behind the upper and lower eyelids, there is a third eyelid that is usually covered. Cat conjunctivitis is typically treated with eye drops or ointments that contain antibiotics, steroids, or both.


What Does a Third Eyelid of Cat Do?

Cats and many other mammals have a third eyelid called the nictitating membrane. The corners of each eye, towards the center of the face, contain this membrane. Usually, a retracted lid covers the third eyelid. Inflammation of the third eyelid may occasionally go along with glaucoma.

Causes of a Cthet’s Third Eyelid

Your cat’s third eyelids are not usually visible. The existence of the third eyelid is typically an indication that something is wrong.

There are several reasons why a cat’s third eyelid could protrude. Some are seen as normal, while others are problematic. In general, if your cat’s third eyelid protrudes for more than a few hours, you should contact your veterinarian.


State of relaxation or drowsiness

The third eyelids frequently droop when a cat is overly relaxed or exhausted. You might notice that the third eyelids are lifted when your cat is sleeping or just after waking up. The third eyelid should close when the cat is conscious and awake. In the event that the third eyelid is elevated for

Fatigue or anesthesia

If your cat received anesthesia or a sedative for a medical procedure, the third eyelid will open and partially cover the eye due to the extreme body relaxation. The impact can last for several hours after waking up, but it should gradually disappear. Unless the third eyelid continues to protrude after the procedure, this is seen to be normal and causes no problems.



The conjunctiva, a thin, transparent mucous membrane, covers the inside of the eyelids and the front of the eye. Conjunctivitis, sometimes referred to as “pink eye,” is nothing more than conjunctival irritation. It could result from an eye irritant, an injury, an infection, or an allergy. The third eyelid frequently becomes inflamed and protrudes as a result of conjunctivitis. An sickness or injury may occasionally be indicated by a protruding third eyelid.

Corneal ulcers

The cornea, which is transparent and covers the front of the eye, protects the iris and pupil. The third eyelid may protrude as a result of a corneal ulcer, a damage to the cornea that causes pain and inflammation in the eye. Usually, corneal ulcers result from eye lesions like scrapes, scratches, or puncture wounds. Another factor that might cause corneal ulcers is exposure to irritants or abrasives. A corneal ulcer requires veterinary treatment and can develop pretty seriously very fast. Cats with corneal ulcers may need to take one or more kinds of eye medications, as well as possibly some oral ones.


Numerous blood vessels can be seen in the uvea, which is the center of the eyeball. The medical word for uveal inflammation is uveitis. It occasionally hurts and frequently makes the area around the attention look pretty red. There’s a chance the third eyelid will be affected.


Glaucoma, a painful eye condition, causes pressure to build up inside the eye. This occurs as a result of the aqueous humor, a fluid that covers the front of the eye, not draining properly. Excessive pressure damages the optic nerve and can result in blindness. In some situations, the third eyelid may protrude and partially envelop the eyeball.

Eye of Chernobyl

The third eyelid gland may enlarge to the point where it appears to protrude roundly from the inner corner of the eye. This is nictitating membrane prolapse, also referred to as cherry eye. It is extremely unusual in most cats, but Burmese cats usually have it. Surgery is used to cure cherry eyes.

Ocular tumors

If there are any growths, tumors, masses, or cysts inside the eye or close by, the third eyelid may swell and protrude. If you see an unusual growth or swelling in your cat’s eye or the area around it, call your vet before it becomes worse.

Disorder of Horner

Actually a neurological condition, Horner’s syndrome is brought on by a damaged nerve. The face muscles and eyes are affected, producing the impression of asymmetrical eyes. The third eyelid of one eye is frequently extremely visible. The eyelids droop, and the eye itself seems to have “sunk in.” Horner’s syndrome may be brought on by trauma or a tumor, however occasionally the exact cause is not known. It’s possible that the issue will resolve itself.

What to Do When You Notice Your Cat’s Third Eyelid

There is probably something wrong if your cat’s eyelid protrudes and it doesn’t seem to be connected to sleep, relaxation, sedation, or anesthesia. Consult your veterinarian as soon as possible if you require advice. If your cats are displaying other sickness signs, take them to the doctor as soon as you can for a checkup. Avoid attempting to put anything in the eye without your veterinarian’s permission as doing so could substantially worsen the issue. If you have eye issues, don’t wait to see your veterinarian since they could soon grow worse.

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