Glaucoma in Cats: Eye Pressure, Warning Signs and Treatment

By Dr Duncan Houston

A cloudy eye, enlarged pupil or sudden reluctance to jump can mean more than a minor irritation. Glaucoma damages the eye when pressure rises beyond what its sensitive structures can tolerate.

Cats may show surprisingly little outward discomfort. Waiting for obvious crying can allow further loss of vision.

Quick Answer

Glaucoma is damage associated with abnormally high pressure inside the eye. A red, cloudy, enlarged or painful eye, or any sudden change in vision, needs veterinary assessment today. Treatment aims to lower pressure, address the cause and preserve comfort; vision already lost from nerve damage may not return.

Why do cats develop glaucoma?

Fluid normally circulates through the eye and drains away. Obstructed drainage can raise pressure and injure the retina and optic nerve. In cats, glaucoma is commonly secondary to another problem such as inflammation inside the eye, a tumour, bleeding or an abnormal lens position.

Primary inherited glaucoma exists but is uncommon in cats. The Cornell feline glaucoma overview describes why looking for the underlying eye disease matters.

How is it diagnosed and treated?

The vet measures eye pressure with a tonometer and examines the cornea, pupil, lens and deeper eye structures. Both eyes should be assessed. An eye that looks cloudy is not automatically glaucomatous, and a photograph cannot measure pressure.

Treatment may involve pressure-lowering drops, treatment for inflammation or infection when appropriate, and referral to an ophthalmologist. Some medicines used in dogs do not work the same way in cats. In particular, prostaglandin drops are not a routine interchangeable choice for feline glaucoma. The Merck treatment review explains these species differences.

If an eye is permanently blind and painful, removing it can provide lasting pain relief. That decision considers the cause, comfort and the other eye; keeping a painful blind eye is not always the kinder option.

How worried should you be?

What you notice	Why it matters	What to do
Subtle pupil change or increasing cloudiness	Pressure or another eye disease may be changing	Arrange assessment today.
Squinting, redness or apparent vision loss	Potential active pain and sight-threatening disease	Seek urgent assessment now.
Known glaucoma worsening despite prescribed drops	Pressure may be uncontrolled	Contact the treating clinic immediately.

What else could explain these signs?

Corneal ulcers, uveitis, lens displacement and high-blood-pressure retinal detachment can resemble aspects of glaucoma. Some cause low rather than high eye pressure. This is why leftover eye medication can be the wrong treatment.

When is this an emergency?

Sudden blindness, a very painful eye, a rapidly enlarging eye or eye changes after trauma require immediate veterinary attention. Use an emergency clinic if your usual practice is closed. Do not press on the eye or wait overnight to see whether vision returns.

What should you do next?

Call the clinic and describe when the change started and whether one or both eyes are involved.
Keep your cat indoors, away from stairs, in a dim comfortable area.
Bring all current eye medicines and use only the instructions already prescribed for this cat; ask before changing treatment.
Attend pressure rechecks even if the eye looks calmer. Appearance alone does not prove pressure is controlled.

Common mistakes to avoid

Assuming cats with painful eyes must cry or paw at them.
Borrowing another pet’s glaucoma drops.
Using steroid drops without ruling out a corneal ulcer.
Stopping prescribed drops because redness improves.

Prevention and ongoing care

Most secondary glaucoma cannot be prevented with diet or supplements. Prompt investigation of inflammation, trauma and changes inside the eye can reduce delays in care.

For a cat with reduced vision, maintain predictable furniture placement, accessible resources and safe indoor enrichment. Ask the ophthalmologist how often the other eye should be checked.

Frequently asked questions

Can a cat recover vision after glaucoma?

It depends on the damage and how quickly pressure is controlled. Permanent optic nerve or retinal damage cannot be reversed.

Is feline glaucoma painful?

It can be, even when a cat is quiet rather than visibly distressed.

Can human glaucoma drops be used in cats?

Some active ingredients are prescribed by vets, but product choice and frequency must be tailored to the cat and cause.

Can a cat live well with one eye?

Many adapt well after pain is relieved, with a safe environment and monitoring of the remaining eye.

Treat a changing eye as a time-sensitive problem. Measuring pressure and identifying its cause offers the best chance of protecting comfort and any remaining sight.

For more practical animal health information, explore ASK A VET™. If your animal has emergency signs, contact a veterinary clinic immediately.