A cataract is any opacity of the lens of the eye. The normal lens is translucent (clear), and it transmits and focuses light onto the retina in the back of the eye. A cataract within the lens may block the transmission of light to the retina.

There are many causes of cataracts. Cataracts may be inherited or related to some other disease process. Most cataracts in the cat develop secondary to inflammation within the eye, from trauma or some other eye problem. Rarely, cataracts in the cat may be inherited, may arise with abnormal development of the lens, or may occur in association with nutritional abnormalities in the young cat.

Cataracts are not the same as nuclear or lenticular sclerosis, an aging change that often occurs in the feline lens and does not cause blindness. Cataracts are not as common in cats as they are in dogs. The finding of a cataract in a cat's eye should lead to a search for an underlying problem.

Cataracts cause varying levels of vision impairment and may lead to blindness.

What to Watch For

Bluish, gray or white color change inside of the eye

Tendency to bump into things

Reluctance to use stairs or jump up onto objects

Hesitancy in unfamiliar environments

Other signs of blindness

Redness and inflammation

Pain and squinting due to the underlying cause

Diagnosis

Diagnostic tests are necessary to recognize cataracts and exclude other diseases. Tests may include:

A complete medical history and physical examination.

A complete eye examination. Most veterinarians have the tools with which to confirm the presence of a cataract in the lens, but it is often necessary to visit a veterinary ophthalmologist to have a more thorough examination performed using an indirect ophthalmoscope and a slit lamp biomicroscope.

Blood tests to determine underlying causes.

An ultrasound examination of the eye if the cataract is too opaque to allow examination of the retina.

Possibly an electroretinogram to evaluate the function of the retina, especially if the cataract blocks visualization of the retina.

Treatment

Treatment must be aimed at correcting the underlying cause of the cataract.

When cataracts are caused by inflammation (uveitis) within the eye, the inflammation may be treated with anti-inflammatory drugs and certain antibiotics.

There is no medical treatment available to reverse cataracts, to prevent cataracts or to shrink cataracts.

Cataracts that are inherited or appear to arise spontaneously may be surgically removed. Cataracts associated with inflammation in the eye cannot be removed surgically unless the inflammation is brought under control. Many cats with cataracts are poor candidates for surgery because they have inflammation within the eye.

Whether a cat is a candidate for cataract surgery can be determined by a veterinary ophthalmologist.

Home Care and Prevention

It is important to have all cats with cataracts examined early in the course of their disease as the cataract is frequently a sign of another underlying problem. Inflammation in the eye (uveitis) is the most common cause of cataract development in the cat, and uveitis often indicates the presence of a systemic disease; therefore, it is important to examine and perform diagnostic tests in all cats with cataracts.

Even if the cat is not a candidate for surgical removal of the cataracts, there may be other medications needed to treat underlying diseases. If your cat has inoperable cataracts, he may require help adjusting to his blindness. Be sure to keep objects around the house in a consistent place and confine the cat to the house or an enclosed porch, patio or yard. Most blind pets function extremely well in familiar environments.

There is nothing you can do to prevent cataracts.