What exactly is happening inside a cat's eye when a cataract forms?

The lens is a clear, flexible disc made mostly of water and structural proteins called crystallins, arranged in a precise pattern that keeps it transparent. A cataract develops when those proteins clump or the fiber layers separate, scattering light instead of letting it pass through to the retina, and the degree of clouding can range from a small fleck to complete opacity of the lens (Merck Veterinary Manual, 2023). Because the lens has no blood supply, it depends on the surrounding aqueous and vitreous fluid for nutrients, so anything that changes the chemistry of those fluids, including inflammation or trauma, can trigger cataract formation.

Cataracts are distinct from the normal, gradual haze called nuclear sclerosis that many cats develop after about seven years of age, which affects the lens's clarity slightly but does not significantly block vision, according to the Cornell Feline Health Center (Cornell Feline Health Center, 2022). Differentiating the two requires a veterinary eye exam, since owners often cannot tell them apart just by looking.

What are the first signs a cat owner is likely to notice?

The most obvious early sign is a visible change in the eye itself: a pearly, white, or bluish-gray sheen over part or all of the pupil that does not blink away. Because cats rely heavily on hearing and smell, many compensate so well for partial vision loss that behavioral signs lag behind the visible eye changes, according to the Cornell Feline Health Center (Cornell Feline Health Center, 2022).

Once a cataract affects a larger portion of the lens, owners commonly report bumping into furniture in dim light, hesitating at stairs, reduced interest in jumping onto counters or cat trees, and increased startling when approached from the side. Some cats also develop a change in eye color or size, squinting, or discharge if the cataract is accompanied by uveitis, the intraocular inflammation that frequently underlies feline cataracts.

Why do cats get cataracts in the first place?

Unlike dogs, primary hereditary cataracts are uncommon in cats; feline cataracts are far more often secondary to another problem inside or around the eye. Chronic anterior uveitis, inflammation of the iris and ciliary body, is the leading cause and can stem from feline herpesvirus-1, feline infectious peritonitis, toxoplasmosis, or immune-mediated disease, with the inflammation itself damaging lens fibers over time (Merck Veterinary Manual, 2023).

Blunt or penetrating trauma to the eye, retinal detachment, and intraocular tumors are additional recognized causes, and diabetes mellitus, while a common cataract trigger in dogs, is a much rarer cause in cats. Aging can play a contributing role as lens metabolism slows, but age-related cataracts severe enough to impair vision are less frequent in cats than the secondary, disease-driven form, which is why veterinarians investigate an underlying cause any time a cat is diagnosed.

How do veterinarians confirm a cataract and rule out other eye problems?

Diagnosis starts with a slit-lamp biomicroscopy exam, which lets the veterinarian magnify and illuminate the different layers of the lens to determine the cataract's stage, from incipient to mature or hypermature, and to check for signs of lens-induced uveitis (American College of Veterinary Ophthalmologists, n.d.).

Because uveitis is so often the culprit, a full diagnostic workup typically includes measuring intraocular pressure with tonometry to screen for secondary glaucoma, a fundic exam to evaluate the retina, and bloodwork or specific testing for feline leukemia virus, feline immunodeficiency virus, toxoplasmosis, or FIP when infectious disease is suspected. An ocular ultrasound is often recommended before considering surgery, since it can reveal whether the retina is still attached behind a dense cataract that the vet cannot see through directly.

Can a cat's vision actually be restored, and is surgery worth it?

Cataract surgery, using a technique called phacoemulsification to break up and remove the clouded lens, is currently the only treatment that can restore vision lost to a mature cataract, and it is performed almost exclusively by board-certified veterinary ophthalmologists (Merck Veterinary Manual, 2023). Reported costs for the procedure commonly fall in the range of $2,700 to $4,000 or more per eye once pre-surgical workup, anesthesia, the surgery itself, and follow-up rechecks are included, though pricing varies significantly by region and case complexity.

Because most feline cataracts are tied to uveitis, controlling that underlying inflammation before and after surgery is essential to a good outcome; cats with poorly controlled uveitis have a higher risk of surgical complications such as glaucoma or retinal detachment. Not every cataract needs surgery: small, non-progressive, incipient cataracts that are not causing functional blindness may simply be monitored with periodic rechecks rather than operated on.

What day-to-day care does a cat need while living with a cataract?

For cats not undergoing surgery, ongoing management centers on treating the underlying disease driving the cataract and controlling secondary inflammation, often with topical anti-inflammatory or antiglaucoma eye drops prescribed after the diagnostic workup, along with rechecks every few months to monitor intraocular pressure and cataract progression.

Cats adapt remarkably well to vision loss as long as their environment stays consistent: keeping food, water, litter boxes, and furniture in fixed locations, adding nightlights, and avoiding rearranging rooms helps a partially or fully blind cat navigate confidently. Owners should also watch for signs the other eye is being affected, since bilateral involvement is common when the underlying cause is systemic, such as infectious or immune-mediated uveitis.

What's the long-term outlook for a cat diagnosed with cataracts?

Prognosis depends far more on the underlying cause than on the cataract itself; a cataract from a resolved, one-time injury may never progress, while one driven by chronic, poorly controlled uveitis can progress to glaucoma or lens luxation, both of which threaten the eye's comfort and long-term retention, not just vision. Cats tolerate blindness in one or even both eyes better than many owners expect, often maintaining a good quality of life through their other senses (Cornell Feline Health Center, 2022).

For surgical candidates with a healthy retina and well-managed uveitis, vision outcomes after phacoemulsification are generally favorable, though lifelong anti-inflammatory eye drops and periodic ophthalmology rechecks are usually still required to keep the eye comfortable and pressure normal.