Glaucoma in cats is a condition in which the pressure inside the eye reaches abnormal levels. This increase in pressure damages the optic nerve and retina of affected cats, creating a multitude of problems.
Feline glaucoma is a progressive disease that develops quickly and has permanent effects.
But before that, let’s talk about what glaucoma in cats is. We’ll talk about everything you need to know about this eye issue, from the signs right up to how it’s prevented.
What Is Glaucoma in Cats?
To get a good grasp on what glaucoma is and how it works, it's crucial to understand a few terms.
Aqueous Humor. The aqueous humor is the fluid inside the eyeball that maintains eye pressure.
Ciliary Body. The ciliary body is responsible for producing the aqueous humor and aids the lens in focusing on objects.
Intraocular Pressure. IOP is the pressure of the fluid inside the eye.
Iridocorneal Angle. Otherwise known as the drainage angle, the iridocorneal angle is the primary passageway for the outflow of the aqueous humor.
Normally, a cat’s eyes constantly produce and drain fluid at a stable rate. This continuous process supplies the eyes with nutrients and maintains the pressure within the eye. When this process gets obstructed, then IOP increases.
What are the Types of Glaucoma in Cats?
Feline glaucoma is generally categorized into two types: primary and secondary glaucoma.
Primary Glaucoma
This type of glaucoma is considered rare, which often happens due to inherited factors and structural abnormalities of the eye’s structure, particularly the drainage system.
Some cat breeds develop narrowly formed drainage angles, which slow down the outflow of the aqueous humor. Because of this slow drainage, the pressure accumulates and builds up over time. Cat breeds that carry an increased risk of glaucoma include:
Secondary Glaucoma
Secondary glaucoma in cats is a more common type, as it happens because of another underlying health or eye condition. This type often occurs later in life and can progress rapidly depending on the cause. Common factors include:
Uveitis. Uveitis is the painful inflammation of the middle layer of the eye. This results in swelling and protein buildup, which can result in the obstruction of the eye’s drainage angle.
Lens Dislocation. The lens, which is held together by zonules, can shift forward or backward, causing problems with the outflow of fluid.
Intraocular Tumors. Tumors can block or compress the structures that are involved in the drainage of the aqueous humor.
Eye Injuries and Intraocular Bleeding. Injuries to the eye, such as blunt trauma, scratches, or penetration, result in intraocular bleeding, which can negatively impact the drainage system.
Advanced Cataracts. When the lens becomes clouded from advanced cataracts, this can block the normal flow of fluid within the eye, causing increased intraocular pressure.
What are the Symptoms of Glaucoma in Cats?

Glaucoma in cats often develops silently, with subtle signs that can be easily missed. These include:
Redness in the Eye. One of the earliest indicators of increased pressure in the eyes is the presence of a red color. The redness can come from the dilation of the blood vessels.
Frequent Squinting or Blinking. Affected cats may squint or blink more frequently because of the constant discomfort they feel. Some may keep their eyes partially closed.
Excessive Tearing or Watery Eyes. Another sign is tearing or watery eyes. An increase in tearing can happen as the eye enlarges and tries to flush out the fluid.
Cloudy or Bluish Cornea. Swelling in the cornea, as caused by fluid buildup, can make the eyes look cloudy or hazy.
Enlarged Eyeball. In advanced cases, the eyeballs may look enlarged. This occurs due to persistent pressure.
Vision Loss or Disorientation. If your cat starts bumping into objects, hesitates to enter unfamiliar spaces, or has trouble navigating, it might be losing its vision.
Unequal Pupil Size. One pupil may look larger than the other if the affected eye has increased pressure.
Behavioral Changes. Cats may appear irritated and withdrawn, while some may tend to hide or have a reduced appetite.
Is Glaucoma Painful for Cats?
Glaucoma can be very painful for cats, especially as eye pressure increases. In advanced stages, the pain can progress to other areas around the eyes, causing headaches and nausea. While they might feel pain, cats are known to hide their feelings.
How Does a Vet Check for Glaucoma?
Diagnosing glaucoma can’t be fully assessed with an ocular exam. The main methods for diagnosing glaucoma in cats include tonometry, gonioscopy, and ophthalmoscopy.
Tonometry helps us measure the IOP of your cat, giving us a numerical reading we can work with. This process starts with numbing drops and then continues by gently touching the tonometer on the surface of the eyes.
In normal eyes, the usual IOP range is from 10 to 25 mmHg. If the value is above 25 mmHg, we’ll recommend starting treatment and management for feline glaucoma.
However, values above 40 mmHg will require urgent treatment and care to avoid losing your cat’s vision permanently.
One more test we can do is a gonioscopy, which uses special lens to asses the shape of your cat's drainage angle. If we notice any narrow or abnormally formed structures, then this generally suggests a genetic issue.
Additionally, we can do an ophthalmoscopy to assess the optic nerve and retina for signs of damage.
What Is the Treatment for Glaucoma in Cats?

Our vets treat glaucoma in cats by reducing the pressure in the eye. Here are the methods we use:
Medical Treatments
Eye drops are often prescribed to help your cat’s eyes have reduced pressure, decrease fluid production, and help with fluid drainage. These may include medications such as carbonic anhydrase inhibitors, beta-blockers, and prostaglandin analogs.
Depending on your cat’s condition, we can prescribe oral medications. Other medicines, such as antibiotics and anti-inflammatory medications, can be used to treat the specific cause of IOP.
Surgery
The surgical techniques we use depend on your cat’s situation and can range from cyclodestructive to filtering procedures and enucleation.
Cyclodestructive procedures destroy the ciliary body. One example is cyclophotocoagulation. The process works by targeting a part of the ciliary body to help reduce fluid production, lowering IOP. This is generally the treatment considered when other less invasive treatments aren’t suitable for your cat.
Filtering procedures help create new options and pathways for the fluid to drain, reducing IOP. One example is the insertion of a tiny tube in the eye. Another method is by inserting an aqueous shunt implant to increase the outflow of aqueous humor.
For cases wherein the condition doesn’t respond to other forms of treatment, completely removing the eye would be an option. This process, called enucleation, alleviates pain and uncontrollable pressure.
Glaucoma in Cats Prognosis
The prognosis for cats with glaucoma depends on how early it’s caught and whether it can still be managed. In many cases, the disease progresses even with steady treatment. Medication and surgery can only delay the onset of blindness.
However, if caught early, it may be possible to significantly slow down the disease, especially when IOP is well-controlled. Feline glaucoma is still a lifelong condition that requires ongoing management and monitoring.
How Do I Help My Cat With Glaucoma at Home?
For cats with glaucoma, consistent care and management will be needed. Give their medications on time and make sure to limit stress.
If your cat has partial or complete blindness, it’s best to make a few home adjustments to make them more comfortable. Keep their living areas safe and use scent or texture markers in bedding, food bowls, and litter boxes.
How Can Feline Glaucoma Be Prevented?
While feline glaucoma is not entirely preventable, there are some ways to reduce the risk by protecting your cat against several eye problems.
For one, routine vet visits are important to detect any eye issues early on, including glaucoma and other conditions that can cause it.
Also, keep an eye out for your cat’s activity. Any injury or trauma to the eye can cause glaucoma, which is challenging to manage. Additionally, keep your cat’s eyes clean regularly to prevent them from scratching.
“Your cat may not speak, but their eyes tell a story. Keep them healthy, and that story stays bright.”
- Dr. Nenad Misura
Conclusion
Glaucoma in cats is a serious condition that requires proper attention. By keeping your cat safe and its eyes protected, you can significantly reduce the risk of glaucoma.
But while it’s not entirely preventable, there are ways to manage the condition and provide a happy life for your best friend.
Share