Feline glaucoma is an eye disease characterized by high eye pressure (aka intraocular pressure). It can cause pain and potentially blindness. The increase in eye pressure is caused by reduced drainage of the aqueous humor — a clear fluid that circulates between the cornea and pupil.

Normal eye pressure in cats generally ranges from 10 to 20 millimeters. Pressure may vary based on the time of day, the cat's level of excitement or anxiety and their positioning. Eye pressure above 25 mm or a significant difference in pressure between eyes — generally greater than 7 to 8 mm — is considered abnormal.

Thankfully, Glaucoma in cats is relatively uncommon compared to glaucoma in dogs. However, the actual prevalence of the disease might be higher since many cases may go undiagnosed due to the often subtle nature of the associated clinical signs.

Causes of Glaucoma in Cats

Causes of feline glaucoma can be divided into two major categories:

  • Primary Glaucoma: Primary failure of the eye's ability to drain fluid
  • Secondary Glaucoma: An underlying disease that obstructs the normal outflow of fluid in the eye

Primary Glaucoma

Primary glaucoma is hereditary or breed-related and is quite rare in cats. Certain breeds, such as the Burmese, Persian and Siamese are more prone to primary glaucoma than other breeds. The onset of signs typically occurs in one eye first. However, if one eye develops glaucoma, There's a high likelihood that the other eye will eventually become affected as well.

Secondary Glaucoma

Among cats with glaucoma, secondary glaucoma is more common. It occurs secondary to another disease. Getting diagnostic testing to determine the underlying cause of the glaucoma is critical. Once the cause is determined, your veterinarian can recommend appropriate treatment and give a prognosis for your cat's vision loss.

Common Diseases That Cause Feline Glaucoma

The most common underlying diseases that result in feline glaucoma include:

  • Neoplasia: Neoplasia refers to an abnormal growth of tissue. Intraocular neoplasia, often a cancerous mass, is the leading cause of glaucoma in cats, with melanoma and lymphoma being the most common types of cancer affecting the eye.
  • Anterior uveitis: Refers to inflammation in the front portion of the eye and is a major cause of feline glaucoma.
  • Intraocular hemorrhage (Bleeding inside the eye): This most commonly occurs secondary to high blood pressure or trauma.

A long hair orange and white Persian cat with their eyes closed.

Signs of Glaucoma in Cats

Clinical signs of feline glaucoma are often very subtle and may be difficult for cat parents to notice. Signs of feline glaucoma include:

  • Squinting
  • Eye discharge
  • Dilation of the pupil
  • Prominent blood vessels on the white of the eye
  • A hazy or blue appearance to the eye
  • Loss of vision

In later stages of the disease, the eyeball becomes enlarged and looks bulgy, and blindness sets in. Cats respond to the discomfort differently. In most cases, though, cats don't show obvious signs of severe pain despite this being a very painful condition. Unfortunately, this means that many cats are diagnosed in the late stages of the disease and are already blind at the time of diagnosis.

Diagnosis and Treatment of Glaucoma in Cats

If you suspect your cat has glaucoma, this should be considered an emergency. Your cat should be evaluated by a vet as soon as possible to reduce the risk of further damage to the eye. Vets diagnose glaucoma in cats based upon clinical signs and by measuring eye pressure. Your vet may use multiple devices to do this.

Unfortunately, in most cases of feline glaucoma once vision is lost it can't be restored. In cats with primary glaucoma, vision loss occurs gradually over time, even with treatment. In cats who have secondary glaucoma, the prognosis depends on the underlying disease causing the glaucoma as well as how the underlying disease and the glaucoma respond to treatment.

There are medicines that can help lower eye pressure and treat glaucoma in cats. Topical medicines must be applied consistently, multiple times a day. While it can be challenging to give your cat medicine, it's not impossible and your vet can help you come up with tricks to make your life easier.

Sometimes the recommended treatment for feline glaucoma is surgery to remove the eye. In cats with irreversible blindness or where cancer is the suspected underlying cause of the glaucoma, removing the eye is usually the most appropriate treatment option. Although it can be stressful to make the decision to remove your pet's eye, remember that the eye is extremely painful. Cats actually do very well with this surgery because a source of discomfort has been removed, and they are usually already adapted to vision loss in the affected eye. Even cats that are blind in both eyes can adapt and do very well following surgery.

Dr. Jessica Seid Dr. Jessica Seid

Jessica Seid is an emergency veterinarian practicing in the New England area. She is a graduate of the North Carolina State College of Veterinary Medicine and has been in the field for more than a decade. When she's not helping patients, she enjoys spending time with her husband, daughter and French bulldog.

Related articles

Cat & Kitten Swollen Belly: Causes, Diagnosis and Treatment

Learn the many causes that can give your cat or kitten a swollen belly, from organ-related issues to simple gas, how it's diagnosed and treatment options.

Allergic Dermatitis & Skin Conditions in Cats: Causes & Treatments

Discover some of the signs of feline skin conditions, how to help improve them, and when to consult your veterinarian about your cat's skin health.

Cat Ear Emotions: How Cat Ears Move With Their Mood

Learn how your cat's ear language and movements can show you their underlying emotions, including what a variety of different positions mean.

Explaining Your Cat's Greeting

Learn about the different types of greetings cats can show you, such as head butting or slow blinking, and how to interpret each of her signals.

Cat Pneumonia: Signs, Diagnosis & Treatment

Cat pneumonia can be life-threatening if not addressed when clinical signs start to show. Luckily, many cats treated for this illness recover.

Top 5 Tips For You After Adopting a New Cat

Adopting a cat feels like an easy choice, but ensuring their comfort takes preparation. Follow these tips for a lifetime of love with your new cat.

How to Choose the Right Cat Nutrition for Your Cat

Find out what healthy cat nutrition entails and how to choose the healthiest cat food. Also, learn about common cat feeding concerns and myths.

All About Feline Bartonella

Explore the signs of feline bartonella and learn if it can be transmitted to other pets or humans. If your cat is showing symptoms, learn how you can help.

What Is My Cat's Body Language Telling Me?

Learn to decipher your cat's numerous non-verbal language queues, including the meanings behind expressions through her eyes, ears, tail and stance.

Important Information on Food Allergies & Intolerance in Your Cat

Understand how food allergies and intolerances present themselves in cats, and what you can do to prevent and care for cats with allergies.

Smart Litter Boxes: What You Need to Know

Learn helpful information about self-cleaning litter boxes, including how they actually work, overall benefits, typical costs and transitioning tips.

Weight Gain in Your Cat & How You Can Help

Learn the different factors that might be contributing to your cat's weight gain, and how bigger doesn't always mean better.

Cat's Upset & Sensitive Stomach: Treatments & Food Choices

Just like people, cats can experience occasional stomach upset. If your cat exhibits any of the following, especially after eating, she may have a sensitive stomach.

Setting the Facts Straight: Common Myths About Your Cat

Discover the truths behind some common cat myths you may have heard. With all the misinformation available online about cat, it's time you got the facts.

4 Ways to Help Your Cat Maintain an Ideal Weight

Follow these 4 easy steps to help your cat attain its ideal weight and maintain a healthy weight for life.

Five Common Cat Digestive Problems

Discover some vet-recommended advice about some common cat digestive problems, including how to deal with upset stomachs, worms, hairballs, and more.

How to Talk to Cats (and Are They Really Listening?)

Learn tips for talking & communicating with your cat, including suggested gestures like blinking, as well as how to tell if they are actually listening.

Why Cats Groom Themselves

Cats are built to groom themselves from their tongue to their coat. Read more about their grooming habits so you can understand their needs.

Why Do Cats Try to Eat Plastic?

You may wonder why your cat loves chewing & eating all kinds of plastic. Find out why she's fascinated by these items and what you can do to discourage it.

Cat Bullying: What It Is & How to Stop It

Learn what a bully cat is, why cats demonstrate bullying behavior, and how to stop one cat from constantly bullying others.