Feline glaucoma occurs due to high pressure in the fluid of the eye. The normal feline eye constantly produces and eliminates a fluid known as aqueous humor. When this fluid can't drain properly, pressure builds up inside the eye and can lead to nerve damage and vision loss.
Causes of Feline Glaucoma
There are two types of feline glaucoma, primary and secondary. Primary feline glaucoma occurs due to structural or functional problems with the part of the eye that allows the aqueous humor to drain. This type of glaucoma is rare in cats, and is usually an hereditary condition.
Secondary feline glaucoma occurs as a complication of some unrelated eye problem. There are a number of eye diseases that can precipitate secondary feline glaucoma. Secondary glaucoma is far more common in cats than primary glaucoma.
Causes of secondary feline glaucoma include inflammation, especially chronic inflammation of the iris. Inflammation causes proteins and other debris to circulate in the aqueous humor. These debris can lead to a blockage in the part of the eye that allows aqueous humor to drain.
Lens luxation, or dislocated of the lens of the eye, can also cause secondary feline glaucoma. The lens of your cat's eye can slip into the inner chamber of the eye when it becomes dislocated, blocking the drainage of fluid through the pupil. Lens luxation usually occurs as a complication of severe inflammation of the iris or other tissues in the eye.
Tumors of the eye can also block fluid drainage, leading to glaucoma. Injury can cause the eye to fill with blood, which can also block drainage of eye fluids.
Symptoms of Feline Glaucoma
Feline glaucoma may affect one or both eyes. If your cat develops glaucoma, the affected eye or eyes may appear inflamed, red, squinty and painful. Your cat's eye may water, and it may appear enlarged or cloudy. Your cat's pupil may no longer react to changes in light.
If glaucoma is severe, your cat may experience vision loss or total blindness.
Diagnosing Glaucoma in Cats
Your vet will need a complete medical history and a thorough physical exam in order to diagnose feline glaucoma. Tell your vet if you're aware of any cases of feline glaucoma in your cat's ancestry.
Your vet will perform a veterinary eye exam to confirm glaucoma and try to determine its cause. During this exam, your vet can examine the amount of damage to the optic nerve and retina of your cat's eye. Your cat may need to visit a feline ophthalmologist for a more thorough eye exam.
A veterinary ophthalmologist will measure the amount of pressure inside your cat's eye. He'll perform a gonioscopy to determine the extent of damage to the drainage pathways of the eye. Ultrasounds of the eye can help determine the extent of damage to the eye and can help identify tumors and injuries to the eye.
A combination of surgery and medication may be necessary to treat feline glaucoma. Your vet will want to reduce pressure in the eye and try to save as much of your cat's vision as possible. Medication can help treat any underlying infections related to secondary feline glaucoma.