Glaucoma in cats is an eye condition, similar to that in humans, that leads to a painful buildup of pressure inside the eye. This increased pressure can cause damage to the optic nerve and may result in blindness if left untreated. With early veterinary care—such as prescription eye drops for glaucoma in cats to lower eye pressure—most cats can maintain their vision and live comfortably despite the disease.
What is glaucoma in cats?
Glaucoma in cats is an eye disorder characterized by abnormally high intraocular pressure (IOP), the internal pressure of the eye. This pressure buildup damages the optic nerve over time, potentially leading to vision loss. Veterinarians measure this pressure using a device called a tonometer to diagnose and monitor the condition.
What is intraocular pressure, and how is it maintained in cats?
The inside of a cat’s eye is filled with a clear fluid called aqueous humor, which helps maintain the eye’s shape and size. The intraocular pressure (IOP) refers to the pressure of this fluid within the front (anterior) chamber of the eye.
The ciliary body is responsible for producing aqueous humor and also contains the ligaments that hold the lens in place. Muscles in this area adjust the lens’s shape to focus vision. The aqueous humor delivers nutrients and oxygen to eye tissues and then drains out through the iridocorneal angle (also known as the filtration or drainage angle).
When the production and drainage of aqueous humor are balanced, intraocular pressure remains normal, keeping the eye healthy and preventing conditions like glaucoma in cats.
What causes glaucoma in cats?
Glaucoma in cats develops when the aqueous fluid inside the eye doesn’t drain properly — not because it’s being overproduced. This leads to a buildup of fluid and an increase in intraocular pressure (IOP). The condition is divided into primary and secondary glaucoma.
Primary glaucoma occurs due to structural abnormalities in the drainage angle of the eye. Although it’s uncommon in cats, the Siamese and Burmese breeds may be more prone to it.
Secondary glaucoma, the more common form, develops as a result of another eye disease or injury, typically in older cats. Common causes include:
- Uveitis (inflammation inside the eye) or infections that block the drainage angle with debris or scar tissue.
- Lens dislocation, where the lens moves forward and blocks fluid drainage.
- Eye tumors, which can obstruct the iridocorneal angle.
- Intraocular bleeding occurs when blood clots prevent fluid from draining out of the eye.
- Lens rupture from trauma, causing protein leakage, inflammation, and swelling that block drainage.
Understanding these causes helps detect glaucoma in cats early and prevent irreversible vision loss.
Why is increased intraocular pressure a problem in cats?
When intraocular pressure (IOP) becomes too high, it causes serious damage to the retina and optic nerve, leading to vision loss or blindness.
The retina is the thin, light-sensitive layer lining the back of the eye. It contains rods and cones, which detect light and convert visual images into electrical signals. These signals are then transmitted through the optic nerve to the brain, allowing vision to occur.
With glaucoma in cats, elevated pressure inside the eye compresses these delicate structures, disrupting blood flow and causing degenerative changes. Over time, this irreversible damage to the retina and optic nerve results in partial or total blindness if not treated promptly.
Glaucoma in Cats Symptoms
The most common signs your cat may experience include:
- Eye pain: Your cat might keep one eye partially closed, squint, or rub at it frequently. She may also turn away when you touch near her head.
- Watery discharge from the affected eye.
- Swelling and bulging of the eyeball, with the white part of the eye (sclera) appearing red or bloodshot.
- Cloudy or bluish cornea (the clear part of the eye).
- Dilated pupils in one or both eyes.
- Blindness can occur rapidly if the intraocular pressure isn’t reduced.
- Lethargy or reduced activity caused by subtle, ongoing eye pain.
Note: Acute glaucoma is an emergency. If you notice any of these symptoms, bring your cat to the veterinarian immediately. Sometimes, an emergency visit to a veterinary ophthalmologist is necessary.
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How Is Glaucoma Diagnosed?
The diagnosis of glaucoma is based on precisely measuring intraocular pressure (IOP) and performing an internal eye examination with specialized instruments.
Glaucoma in Cats Treatment
It is crucial to lower intraocular pressure (IOP) as quickly as possible to prevent permanent damage and potential loss of vision. Addressing any underlying condition that may be causing the glaucoma is equally important.
Pain relief is typically managed with prescribed analgesics to ease discomfort. Medications that help reduce fluid production and enhance drainage are commonly used to control the elevated pressure. Long-term management may include drugs such as carbonic anhydrase inhibitors (e.g., dorzolamide 2%, brand names Trusopt® and Cosopt®) or beta-adrenergic blocking agents (e.g., 0.5% timolol, brand names Timoptic®, Betimol®).
In more serious or advanced cases, surgery may be required in addition to medication. Veterinary ophthalmologists employ various surgical procedures to help lower intraocular pressure. If medical treatment fails or blindness has already occurred, removal of the affected eye may be advised to relieve pain and discomfort.
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Is Follow-Up Treatment Necessary?
After a diagnosis of glaucoma and the start of medication, regular follow-up care is essential. Initially, your veterinarian will recommend regular check-ups to monitor your cat’s response to the treatment and adjust medications as needed.
What Is the Prognosis?
The outlook largely depends on the underlying cause of the glaucoma. Long-term management, including ongoing medical care, is typically necessary to maintain control of the condition. With medication alone, most cats eventually lose vision in the affected eye. However, if the glaucoma is due to a lens luxation and the lens is surgically removed, the prognosis is favorable. Similarly, if secondary glaucoma is caused by uveitis and inflammation is managed effectively, the prognosis remains good with consistent treatment.
