Have you ever wondered how many eyelids cats have? Cats can have three eyelids: one upper and lower lid with an extra eyelid on the inside of the eye.
The third eyelid is often called the haw or nictitating membrane. Veterinarians may refer to this as the palpebra tertia-the Latin term for “third lid.” This small eyelid part may be visible in the inner corner of a cat’s eyes.
What does a cat’s third eyelid look like?
Even if someone looks closely at a cat that is alert, they may not be able to detect how many eyelids cats have. The third eyelid may not be visible when the cat is awake and alert since almost all of it is covered by the cat’s upper and lower eyelids.
The third eyelids of cats may be more visible when the cat is resting if their eyes are partially open. If a cat sleeps with its eyes slightly opened, one might see nictitating membranes, which are small and transparent skin flaps that line the inner corner of an animal’s eye during sleep to protect it.
What is the purpose of a cat’s third eyelid?
The nictitating membrane closes over the eye from the inner corner of the cat’s eye. The purpose of the nictitating membrane is to cleanse the eye by wiping any dust or debris from the surface of the eye.
For cats in the wild, the nictitating membrane may be an important source of protection. Some cat owners have noticed the nictitating membrane closing while the cat is jumping. The instinctual closure of the third eyelid may protect the eye while the cat is running through grass or jumping.
The nictitating membrane adds moisture to the eyes, and it also protects them by spreading defensive substances from the immune system over its surface. The tears that flow over this sensitive area contain cells called lymphocytes which help protect against infection.
Inside the membrane surfaces of the nictitating membranes is a layer of cartilage. Many mammals other than humans have nictitating membranes.
What does it mean if my Cat’s third eye is visible?
A nictitating membrane may partially cover the eye. This abnormal visibility of the third eyelid can be caused by a viral infection.
Common cat eye infections that cause the third eyelid to be visible include:
- Conjunctivitis or pink eye
- Corneal Ulcers
- Horner’s Syndrome
An eye infection that causes the exposure of the third eyelid in a cats eye can also cause diarrhoea, vomiting, and sneezing.
Sometimes the gland of the third eyelid can become inflamed and swollen. This is commonly known as cherry eye and is most common in the Burmese cat breed.
Cat owners should have their cats examined by a veterinarian whenever the cat has a change in health which includes watery eyes, eye discharge and eyelid protrusion.