Red Eyes in Cats
Can be better understood if you have full knowledge of the anatomy of your cats eyes

Red eyes in cats has several potential causes, can be almost painless, or the inverse, and become extremely painful for your cat.

It may also be accompanied by discharge or watery eyes, however, in some cases, it may not.

For an owner to better understand why your cat’s eye or eyes may be red, it is very helpful to fully understand the anatomy of their eyes.

Red eyes are easier to understand with some knowledge of the anatomy of your pets eyes, and it starts with the anterior chamber.

This is the area of your cat’s eye that is behind the cornea and is filled with a liquid that is called aqueous humor.

The next portion is called the ciliary body.

This is the structure that actually produces the aqueous humor or the fluid that is in the front portion of their eyes.

Next is the conjunctiva, which is the lining of the eyelids of your cat.

It is a very thin membrane that covers part of the sclera, which is the white part of your cat’s eyes.

The cornea is the clear covering on the front of the eye, and the iris is the colored portion of the eyes.

Next is the lens, which is the structure of the eye that focuses light on the retina, and then comes the pupil.

The pupil is the actual opening in the iris that appears as a dark circle. Lacrimal glands, eyelashes, and the upper and lower eyelids are also parts of the eyes

However, there is one more major part of your cat’s eyes not well known, that is called the third eyelid.

The third eyelid is the eyelid that is attached to the inner most corner of your cats eyes, and is referred to as the nictitating membrane.

It extends out of the side of the eye when your cat blinks and is the main mechanism that protects the moisture the eyes.

Red eyes in cats will often occur when one of, or several of these eye structures becomes damaged or injured.


Mean green eyes in catsRed eyes in cats have several potential causes

Anterior Uveitis

The first common cause of red eyes in cats is referred to as anterior uveitis and is an inflammation of the either the iris or the culinary body of your cat’s eye.

The symptoms of this potential cause usually start with squinting as it begins to become painful for your cat.

It will also cause the pupil to become constricted as well as what appears to be a swelling in the iris.

It may also cloud your cat’s cornea, which will cause a lot of tearing to occur.

As a result of this, your cat will naturally start to avoid excessive light, including sunlight.

It is usually the result of some type of trauma, but could also be caused by a bacterial infection, a viral infection, or cancer.

It is usually treated with anti-inflammatory drugs as well as medications to help dilute the eyes.


The next common cause of red eyes in cats is from a condition called Conjunctivitis, which is an inflammation of the conjunctiva of the eyes.

When this occurs, the symptoms to watch for are slightly different.

The conjunctiva will become very thick and red, and as a result of this, there will be discharge.

But it will not be a normal discharge, as it will become quite excessive. With this forms of red eyes, the pupil size does not change.

It is almost always the result of infections, allergies, or some type of an irritant to your cat.

Treatment for this potential cause will be antibiotics and medicated eye drops to help keep the eyelids clean.


The next potential cause of red eyes in cats is from glaucoma, which is a very severe condition and is a medical emergency.

When your cat’s eye is normal, it contains just the right amount of fluid to maintain its shape, and your cat’s body is constantly adding as well as removing this fluid.

Glaucoma occurs when the pressure inside of the globe in your cat’s eye becomes higher than normal.

It is very similar to high blood pressure that can cause immediate damage to your cat’s heart, but in this case, it is pressure that will cause the damage.

This excessive pressure can very quickly damage your cats internal eye structures, and if it is not treated, may cause your cat to lose their sight.

It is usually caused by some type of foreign body and treatment begins with the removal of whatever may be causing it.

It is now an emergency and the pressure will have to be reduced, as well as the amounts of aqueous humor. Pain medication will have to be given as it is very discomforting for your cat.

The symptoms usually start with what will appear to be swelling in the eyes followed by dilation of the pupils that will not respond to light at all.

The blood vessels in the white portion of your cat’s eyes will also become so enlarged, that they appear red. This form of red eyes is a very serious situation.

Superficial Keratitis

The next common causes of red eyes in cats is called superficial keratitis and is an inflammation of the eye that is usually the result of bacterial or viral infections.

However it may also be the result of some type of an allergy or trauma.

However, it can also be caused by something that has become a constant irritant to your cat’s eyes.

The symptoms with this form of red eyes will be a cloudy cornea as well as discharge, but it will be nothing like conjunctivitis as it is usually minor.

But there is one thing in common with conjunctivitis; your cat will begin to squint excessively.

With this form of red eyes, antibiotics will be used as well as eye drops as it is paramount to keep both the eyes and eyelids clean.

Cherry Eye

The final common cause of red eyes in cats is called cherry eye, which is where the third eyelid gland has prolapsed.

What happens with this is the gland of third eye lid actually protrudes from behind the eyelid.

It causes a red mass and actually looks like a very small cherry, and the only form of treatment will be surgery.

There are several other potential causes of red eyes in your pet, but they are not as common. They include a corneal ulcer, dry eye, and lens luxation.

It may also be caused by hyphema, which is blood in the eye, a tumor, or may be the result of a foreign object that has entered your cat’s eye.


Red eyes in cats may be the first signal that you will have that something is either terribly wrong with your pet’s eye, or even worse, such as a tumor or cancer that has developed.

Whatever the actual cause is, it should not be ignored as it is certainly not normal.

Pet Medications for Red Eyes in Cats

Cat Vitamin Store

Anisocoria in Cats