Glaucoma in Cats: Signs, Treatment & Prognosis

Glaucoma is a painful eye condition where pressure inside the eye rises above normal. That pressure, called intraocular pressure, builds when the eye’s internal fluid cannot drain properly. Over time, the pressure can injure the optic nerve and other delicate eye structures, which may cause permanent vision loss.

In cats, glaucoma is less often a primary inherited problem and more often a secondary condition caused by another eye disease. Uveitis, or inflammation inside the eye, is one of the most common triggers. Debris, inflammatory cells, blood, or changes in the drainage angle can block fluid outflow and raise pressure.

This is an emergency because the eye can become painful quickly, and vision may be lost in hours to days in severe cases. Some cats show obvious signs like a cloudy or enlarged eye, while others are more subtle and may only hide, squint, or avoid bright light. Early care gives your vet the best chance to protect comfort and, in some cases, preserve sight.

Glaucoma develops when the eye’s fluid drainage system stops working well enough to keep pressure normal. In cats, secondary glaucoma is much more common than primary glaucoma. That means another eye disease usually comes first, and glaucoma develops as a complication.

A leading cause is uveitis, which is inflammation inside the eye. Inflammatory cells, protein, and scar tissue can clog the drainage angle. Uveitis itself may be linked to infections such as FeLV, FIV, FIP, or toxoplasmosis, though some cases have no clear cause. Bleeding inside the eye, lens luxation, advanced cataract-related changes, and tumors can also interfere with drainage.

Primary glaucoma is uncommon in cats but has been reported more often in Burmese and Siamese cats. In those cases, the drainage angle is abnormal from the start. Primary disease is more likely to affect both eyes over time, while secondary glaucoma may affect one eye only.

Because the cause matters so much, your vet will not only measure eye pressure but also look for the disease process behind it. Treating pressure alone may not be enough if inflammation, infection, or a mass is still driving the problem.

Your vet diagnoses glaucoma by combining the eye exam with tonometry, a test that measures intraocular pressure. This is the key test for confirming that pressure is elevated. Many clinics use a rebound or applanation tonometer, and the reading is interpreted along with your cat’s symptoms and the appearance of the eye.

The exam usually also includes checking the cornea, pupil responses, tear production, and the inside of the eye when possible. Your vet may use fluorescein stain to rule out a corneal ulcer before choosing certain medications. If the cornea is too cloudy to see through, ocular ultrasound may help evaluate the lens, retina, bleeding, or a possible mass.

Because glaucoma in cats is often secondary, your vet may recommend additional testing to look for the underlying cause. That can include bloodwork, blood pressure measurement, FeLV/FIV testing, infectious disease testing, or referral to a veterinary ophthalmologist. In some cases, specialized tests such as gonioscopy help assess the drainage angle, especially if primary glaucoma is suspected.

Fast diagnosis matters. The longer pressure stays high, the less likely vision is to return. Even when sight cannot be saved, timely diagnosis still matters because it helps your vet control pain and discuss the most appropriate care options for your cat.

There is no guaranteed way to prevent glaucoma, especially when it develops secondary to another eye disease. The best prevention strategy is early attention to eye problems. If your cat develops redness, squinting, cloudiness, discharge, or a change in pupil size, schedule an exam promptly instead of waiting to see if it clears on its own.

Routine veterinary visits also matter. Cats with a history of uveitis, eye trauma, lens problems, or systemic infections may need closer monitoring because these conditions can raise glaucoma risk. If your cat has had glaucoma in one eye, your vet may recommend monitoring the other eye over time, especially if primary glaucoma is a concern.

At home, avoid using leftover eye medications unless your vet has told you to. Some eye drops are helpful in one condition and harmful in another. Fast, accurate diagnosis is safer than trying to guess.

For pet parents of Burmese or Siamese cats, it is worth mentioning breed risk during wellness visits, even though primary glaucoma is still uncommon overall. Prevention is really about catching the earliest warning signs and treating the underlying eye disease before pressure damage becomes permanent.