Glaucoma in Cats

Cute American shorthair striped cat taking a nap at home

 Kilito Chan / Getty Images

Glaucoma is an eye disease that affects cats as well as humans. It causes a painful increase in pressure inside the eye and can lead to blindness.

What is Glaucoma in Cats?

Glaucoma is a term used to describe a group of eye disorders characterized by increased intraocular pressure, or IOP. It is a progressive condition, meaning it typically gets worse over time.

The eye contains a fluid called the aqueous humor. This fluid is produced in a part of the eye called the ciliary body and drained through a structure called the iridocorneal angle. If the aqueous humor is unable to drain properly, fluid backs up and pressure builds in the eye. A constant increase in IOP can lead to serious damage in the eye.

Signs of Glaucoma in Cats

  • Cloudiness of the eye
  • Squinting
  • Dilated pupil
  • Enlarged appearance of eye
  • Pawing at eyes or face
  • Behavior changes (due to vision loss; may be subtle at first)
  • Lethargy and/or loss of appetite due to pain
  • Clumsiness (due to vision loss)
  • Blindness

Causes of Glaucoma in Cats

Glaucoma is categorized as either primary or secondary. Secondary glaucoma is the most common form of glaucoma seen in cats; primary glaucoma is rare in cats.

Primary Glaucoma

Primary glaucoma is a hereditary condition. Though rare, cats may be born with an anatomical abnormality that affects the drainage of the aqueous humor in one or both eyes. Burmese and Siamese cats appear to have a genetic predisposition to the disease.

Secondary Glaucoma

Secondary glaucoma occurs as a result of another condition and usually occurs in only one eye. Common causes for secondary glaucoma include the following:

  • Uveitis (inflammation inside the eye)
  • Anterior lens luxation (displacement of the entire lens blocks drainage)
  • Eye trauma
  • Bleeding in the eye
  • Advanced cataracts
  • Tumor or similar or growth inside the eye

Diagnosis of Glaucoma in Cats

It's important to bring your cat to the veterinarian if you notice eye abnormalities or any other signs of illness. Problems with the eye can quickly go from bad to worse, so you should not wait to see if your cat improves. Eye disorders may have several signs, so specific eye tests are needed to diagnose glaucoma in cats.

Your vet will begin by discussing your cat's history and performing a physical examination. When examining the eyes, your vet may use a special lens to look at the structures in the eye for evidence of glaucoma. If glaucoma is suspected, your vet will want to check the IOP. This is done through a process called tonometry. A tonometer often looks like a pen-like contraption. It is placed just over the surface of the eye and measures the pressure inside the eye. If the IOP is consistently elevated and other signs of glaucoma are present, then your vet will likely diagnose glaucoma in your cat.

In some cases, your veterinarian may refer you to a veterinary ophthalmologist for consultation. These eye experts have advanced knowledge and specialized equipment that enables them to diagnose your cat's glaucoma quickly and recommend the most effective treatments.

Treatment for Glaucoma in Cats

There is no way to reverse the eye damage done by glaucoma, so early detection is the best way to preserve vision and prevent extreme pain.

Initial treatment for glaucoma generally involves the use of eye drops to reduce intraocular pressure and inflammation. Medications like dorzolamide and timolol work to decrease pressure in the eye. Steroids may be used to reduce inflammation. Glaucoma can be difficult to manage, so expect to see your vet for follow up visits periodically. Your vet will monitor eye changes and adjust medications as needed.

Surgery may be recommended in cases of severe glaucoma and those that don't respond well to medical treatment. Surgical treatment involves the use of a laser to correct the drainage of the aqueous humor.

In cases of blindness or severe disease, your vet may recommend complete removal of the eye.

How to Prevent Glaucoma in Cats

There is no absolute way to prevent glaucoma from occurring in cats. Since primary glaucoma is hereditary, it's important not to breed cats with primary glaucoma. Secondary glaucoma may be prevented if an eye condition is detected before it causes glaucoma. This is why routine veterinary examinations (every year or more) are so important. Your vet may be able to detect eye changes before glaucoma begins or in its earliest stages.