In humans, cataracts are the world's leading cause of blindness. Cataracts in cats are rare, but the disease is still serious; if left untreated, it may lead to blindness. Thankfully, many cases of feline cataracts can be successfully treated.

What Is a Cataract?

Cataracts affect the lens of the eye. The lens helps to focus vision as light that passes through the eye, allowing your cat to see. If this small structure becomes cloudy due to a cataract, it can no longer focus light resulting in blurry vision. The lens is made of mostly proteins and water. Clouding of the lens occurs due to changes in the proteins and lens fibers.

Cataracts in cats are less common than they are in humans and dogs. Furthermore, while humans and dogs can develop cataracts due to diabetes, cats with diabetes typically don't get cataracts. They are also most common among older cats, and Burmese and Himalayan cats are genetically predisposed to the condition. However, cats of all ages and breeds can be affected.

Causes of Cataracts in Cats

Cataracts in cats can develop due to:

• Poor nutrition in early life
• Genetics
• Trauma
• Metabolic disorders
• Radiation
• Inflammation (as with cat cancer, glaucoma, trauma, autoimmune diseases or infection)
• Lens dislocation (typically after trauma or inflammation)
• Cats may also develop cataracts that are related to other diseases such as diabetes or hypertension

Cataracts may develop as a result of uveitis, a type of eye inflammation that can occur as a result of infectious diseases like feline immunodeficiency virus, feline leukemia virus, feline infectious peritonitis and toxoplasmosis. However, it's not always possible to identify the cause of cataracts.

Signs & Symptoms of Cataracts in Cats

Cats are very good at hiding discomfort and vision changes, so it's crucial to look for potential signs of cataracts, such as:

• Hazy or cloudy appearance of one or both eyes
• Behavioral changes (hiding, reduced activity, bumping into familiar objects, difficulty finding their food bowl and/or litter box)
• Disorientation
• Tentative or cautious behavior in unfamiliar places or around stairs

While cataracts aren't considered painful, some conditions that cause them can be. Because of this, a cat with cataracts might also squint or have discharge, redness and swelling around the eye.

Diagnosis of Feline Cataracts

To diagnose cataracts, your veterinarian may perform a variety of tests such as the eye exam and pressure tests. While general practitioners can diagnose most cataracts, they may refer you to a specialist such as veterinary ophthalmologists, who can conduct more sophisticated tests.

These tests may include:

• Advanced eye imaging (including ultrasound)
• Eye pressure testing
• Blood tests for metabolic diseases and infections

If your vet either suspects or diagnoses cataracts in your cat, your veterinarian may recommend that you see a board certified Veterinary Ophthalmologist for further testing and treatment.

Types of Feline Cataracts

Cataracts are classified according to severity and percentage of the lens affected. These are the classifications, according to Animal Eye Clinic:

• Incipient cataracts: Affect less than 15% of the lens
• Immature cataracts: Affect 15% to 100% of the lens; light can still pass through
• Mature cataracts: Affect the entire lens; light passage is impeded

Diagnosing the stage of feline cataracts is essential to selecting the best treatment option.