Glaucoma in Cats: Eye Pressure, Warning Signs and Treatment

By Tailwisp Editorial TeamUpdated October 20, 20264 min read

Glaucoma is one of the eye diseases vets worry about most, because it can lead to blindness within days and causes real pain. Cats are good at hiding discomfort, so owners may notice only subtle changes. Knowing the signs can protect your cat's sight and comfort.

What is glaucoma?

The eye makes a fluid called aqueous humor, which circulates and drains out through a tiny channel at the front of the eye. When drainage is blocked, fluid builds up and the pressure inside the eye rises. High pressure squeezes the optic nerve and retina, and over time damages them, causing permanent vision loss.

Primary and secondary glaucoma

Primary glaucoma, caused by an inherited drainage problem, is rare in cats. Most cats have secondary glaucoma, where another condition blocks the drainage:

• Uveitis. Inflammation inside the eye, often linked to infection, such as FIV, FeLV, FIP or toxoplasmosis. See FeLV and FIV in cats and toxoplasmosis and cats.
• Tumors in the eye, including melanoma.
• Lens luxation, where the lens moves out of place.
• Trauma.
• Bleeding in the eye, sometimes linked to high blood pressure.
• Cancer elsewhere in the body. See cancer in cats.

Signs

• Redness of the white of the eye.
• A cloudy or bluish cornea.
• An eye that appears larger, or bulges.
• A dilated pupil that does not respond to light.
• Squinting or keeping the eye closed.
• Rubbing the eye.
• Watery discharge.
• Vision loss, such as bumping into objects.
• Subtle behavior changes, such as hiding, less play or irritability.

Signs are often missed, because cats can compensate well with one eye.

Diagnosis

The vet measures eye pressure using a tonometer, and examines the eye with special lights. Further tests may include bloodwork, blood pressure and infectious disease testing, ultrasound of the eye and chest X-rays to look for the cause. A referral to a veterinary ophthalmologist may be needed.

Treatment

• Lowering the pressure. Eye drops such as dorzolamide, and sometimes other medications, are used. In an emergency, drugs can be given to reduce pressure quickly.
• Treating the cause. Anti-inflammatory drops for uveitis, treatment of infections and control of high blood pressure.
• Pain relief.
• Surgery, such as laser procedures, in some cases, though less common in cats.
• Removal of the eye (enucleation), or implants, when the eye is blind and painful, or has a tumor. Cats generally cope very well after removal, and the pain is relieved.

Outlook

If treated very early, some vision may be saved, but many cats lose sight in the affected eye. Because secondary glaucoma can signal serious illness, a full workup is important. Cats often adjust well to blindness. See caring for a blind cat.

Monitoring

If one eye is affected, the other may be at risk. Vets often recommend regular pressure checks. Keep appointments, and give drops exactly as prescribed. See how to give cat eye drops.

Prevention

You cannot prevent every case, but you can protect your cat by:

• Taking red or cloudy eyes seriously.
• Keeping vaccinations and parasite prevention current.
• Keeping cats indoors to reduce fights and trauma.
• Getting regular checkups, including blood pressure for older cats. See cat wellness exam: what to expect.

Living with one eye

Cats that lose sight in one eye usually adapt within days to weeks. Keep furniture in the same places, avoid approaching from the blind side without a sound, and keep the litter box, food and water in familiar spots. A cat with vision in only one eye can still play, climb and enjoy life. If both eyes are affected, see caring for a blind cat for ideas on how to help.

Why pain control matters

Glaucoma pain can be severe, and cats may show it only with subtle changes, such as reduced play, hiding or less grooming. If your cat has a blind, enlarged eye, ask your vet about pain relief options and whether removal or an implant is appropriate. Many owners say their cat seemed brighter and happier after surgery, since the constant pain was gone.

What to expect at an eye specialist

A veterinary ophthalmologist can perform detailed pressure checks, gonioscopy, ultrasound and surgery. Referral is useful when the cause is unclear, when both eyes are involved or when surgery is considered. Bring your records, and a list of medications.

Questions to ask

Ask what is causing the pressure, whether the other eye is at risk, how often pressure should be rechecked, which signs would mean an emergency and what the plan is if drops fail. Ask about costs of surgery and alternatives so that you can plan ahead, and about pet insurance coverage. See cat pet insurance guide.

When to see a vet

See a vet the same day if your cat has a red, cloudy or enlarged eye. Use the US vet directory to find a clinic.

This article is general educational information, not veterinary advice. Every cat is different. If your cat is unwell, or you are unsure about a symptom, diet change or medication, contact your veterinarian.