

Key Takeaways
Cataracts can be caused by genetics, uveitis, eye injuries or trauma, health issues, age, nutritional deficiencies, and toxins.
A veterinary ophthalmologist diagnoses cataracts through an ophthalmic exam and slit lamp biomicroscopy.
Phacoemulsification is the definitive treatment for cataracts in cats.
Summary
Feline cataracts happen when the normally clear lens becomes cloudy or opaque, blocking light from reaching the retina. These form when the protein fibers that make up the entire lens are damaged and clump together, significantly hindering vision.
In the early stages, cataracts may only affect a small part of the lens and have little impact on your cat's vision. But when left untreated, this condition can progress to blurry vision and complete blindness.
Early Signs of Cataracts
Cloudy or Opaque Eyes. One of the primary signs of cataracts is the cloudy or opaque appearance. This may be in one or both eyes.
Pupil Changes. The pupils may fail to reflect light normally.
Eye Irritation. Depending on the cause of cataracts in cats, some may experience squinting, redness, or discharge.
Poor Navigation. Affected cats may bump into furniture, have trouble navigating, or move slowly. Some will seem confused or lost.
Changes in Behavior. Your cat may appear more cautious, clingy, or even more easily startled in new environments. Some may hesitate to move.
Sensitivity to Light. Cats with cataracts may avoid brightly lit rooms and may hide under sofas. This happens because incoming light scatters instead of focusing on the retina.

Causes
The leading cause of feline cataracts is uveitis, a condition that causes inflammatory cells and proteins to enter the aqueous humor, damaging lens epithelium and its metabolic processes. This results in the lens fibers becoming opaque.
It's often secondary to an underlying cause, such as feline immunodeficiency virus, feline leukemia virus, feline infectious peritonitis, toxoplasmosis, and even toxin exposure.
This condition also includes genetic predisposition, as some cats have a higher risk of developing cataracts. Inherited cataracts are common in Persians, Himalayans, Birmans, and British Shorthairs.
Direct injuries, trauma, and foreign bodies may also contribute. These break the lens capsule, allowing fluid to accumulate within the lens and result in rapid cataract formation.
Metabolic diseases such as diabetes and high blood pressure can alter the fluid in the eye. One example is when elevated blood sugar levels increase sorbitol, a compound that attracts water in the lens. This will cause the eyes to swell and lead to cataracts.
Age is also a factor. As cats get older (usually those 10+ years old), the lens proteins naturally break down and clump together, and it's a normal aging change. Malnutrition may also be a subtle cause, particularly in kittens fed with improper milk replacers.
Feline Cataracts vs Nuclear Sclerosis
Nuclear sclerosis, also known as lenticular sclerosis, is a normal change in the lens of the eye caused by age. In other words, not all hazy eyes mean an actual cataract. Nuclear sclerosis can also create hazy eyes without the same effect on vision. Here's the difference, according to Dr. Salome.
Features | Cataracts | Nuclear Sclerosis |
|---|---|---|
Appearance | Solid white, opaque, or dense spots that can form anywhere in the lens. | Faint, blue-gray, and often translucent, located in the center of the pupil |
Impact on Vision | Mild to complete blindness | Minimal vision loss |
Causes | Genetics, uveitis, trauma, health issues, nutritional deficiencies, age | Age |
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