Our cats use their eyes to see and understand the world. With each small step they take, they learn more about us and the world. That’s why we must do everything we can to protect them from the many conditions that affect their eyes.
Feline glaucoma is a progressive disease that may lead to blindness in cats. It’s very painful and uncomfortable, easily disrupting their routines and lifestyles.
In this guide, we’ll cover everything you need to know about this eye issue, including what it is, the types, the signs, how it’s diagnosed, and how it’s treated.
Key Takeaways
Glaucoma is a condition characterized by increased intraocular pressure, causing significant pain and potential blindness.
It’s generally caused by inherited traits, uveitis, lens dislocation, intraocular tumors, eye injuries, and advanced cataracts.
Feline glaucoma is treated and managed with medications and surgery.
What Is Glaucoma in Cats?
Glaucoma is essentially a painful eye condition caused by increased intraocular pressure. This damages the retina and optic nerve, potentially leading to blindness. Here are some key terms you need to know to better understand the condition:
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 intraocular pressure. When the aqueous humor fails to drain properly, intraocular pressure may increase, and cats may develop glaucoma.
What Are the Types of Glaucoma in Cats?
Feline glaucoma is generally categorized into two types: primary and secondary glaucoma.
Primary Glaucoma
Feline glaucoma is generally categorized into two types: primary and secondary glaucoma.
Primary Glaucoma
This type of glaucoma is considered rare and often results from inherited factors and structural abnormalities of the eye, 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, pressure builds 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 causes 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. Masses and growths can block or compress the eye structures involved in draining 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?
Feline glaucoma can present with subtle signs that may be difficult to notice. Here are the symptoms our vets observe:
Redness in the Eye. One of the earliest indicators of glaucoma is redness in the white part of the eyes. This may come from the dilation of the blood vessels due to increased IOP.
Frequent Squinting or Blinking. Affected cats may squint or blink more frequently due to constant discomfort. Some may keep their eyes partially closed.
Excessive Tearing or Watery Eyes. Another sign of glaucoma in cats is tearing or watery eyes, which may happen as the eyes enlarge.
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 others may hide or have a reduced appetite.
How Does a Vet Check for Cat Glaucoma?
We start with a physical exam and a few laboratory tests, including tonometry and gonioscopy.
Eye Exam
Our pet ophthalmologists will start with a comprehensive eye exam to identify symptoms. We may also perform an ophthalmoscopy, using a special instrument called an ophthalmoscope.
This helps us magnify and examine the internal structures of the eye, including the retina, optic nerve, and blood vessels.
Tonometry
Tonometry helps us measure your cat's IOP, giving us a numerical reading we can work with. This process starts with numbing drops, then continues with gently touching the tonometer to the surface of the eye.
In normal conditions, the usual IOP range is from 10 to 25 mmHg. If the value is above 25 mmHg, glaucoma may be suspected. However, values exceeding 40 mmHg are considered severe and require urgent treatment to prevent permanent vision loss.
Gonioscopy
A gonioscopy is another specialized test we can do that allows us to directly visualize the iridocorneal angle, otherwise known as the drainage angle of the eye. We use anesthetic drops on the cat’s eyes and use a special contact lens with mirrors.
Using a magnified light source, we can see the anterior chamber and assess whether the fluid-draining structure is open, narrow, or closed.
How to Treat Glaucoma in Cats?
Treatment will include medications, surgery, and supportive care.
Medical Treatments
Medicated eye drops are often prescribed for lifelong management.
Carbonic Anhydrase Inhibitors. Significantly reduces aqueous humor production in the eye.
Beta-Blockers. Also reduces fluid production and is often used with CAIs.
Anti-Inflammatory Medication. Used to treat the underlying inflammation and provide relief.
Surgery
The surgical techniques we use depend on your cat’s situation and may include cyclodestructive procedures and enucleation.
Laser Therapy. 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.
Drainage Implant. Using drainage devices drains excess fluid and reduces intraocular pressure. However, this may carry a higher risk of complications in cats due to the potential for blockage.
Enucleation. For cases involving permanent blindness and painful eyes, enucleation may be performed. This is the complete surgical removal of the eyeball, effectively alleviating pain and pressure.
Recovery and Prognosis for Cats With Glaucoma
Glaucoma requires lifelong management or surgery, with a guarded long-term prognosis for vision. Early veterinary care may slow the progression and relieve pain. If the eye is blind or in severe pain, enucleation is often required for comfort.
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.
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.
Schedule Eye Exams
For one, routine vet visits are important for detecting eye issues early, including glaucoma and other conditions that can cause it.
Monitor Your Cat’s Lifestyle
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.
Manage Underlying Diseases
Since secondary glaucoma may result from untreated eye conditions, seeking professional help is important to prevent the development of glaucoma.
“Your cat may not speak, but their eyes tell a story. Keep them healthy, and that story stays bright.”
- Dr. Nenad Misura
Final Thoughts
Glaucoma in cats is a serious condition that requires proper attention. By keeping your cat safe and protecting its eyes, you can significantly reduce the risk of glaucoma. When you do, you keep your cat happy and healthy.
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