Cataracts

A cataract is any loss of transparency in the lens, the clear disc behind the pupil that focuses light onto the retina. As the lens clouds, less light reaches the back of the eye and vision blurs; a fully mature cataract blocks the light almost completely and the eye becomes blind. Cataracts can affect one eye or both, and range from a tiny speck that barely matters to a dense white opacity.

In cats, cataracts are genuinely uncommon, and that rarity is itself a clue: whereas dogs frequently inherit cataracts or grow them with age, a cat with a cataract usually has something else going on. By far the leading cause is uveitis — inflammation inside the eye, frequently triggered by infections such as FIV, FeLV, toxoplasmosis or FIP. Trauma, diabetes, and a handful of inherited breed forms make up most of the rest.

One important distinction is between a true cataract and nuclear sclerosis, the mild bluish-grey haze that develops in the lens of most older animals. Nuclear sclerosis is a normal ageing change that scarcely affects vision and needs no treatment; only an examination with the right light and magnification reliably tells the two apart, which is why a cloudy eye should always be checked rather than assumed to be "just old age".

Where a cataract is significantly affecting vision, surgical removal by a veterinary ophthalmologist offers the prospect of restoring sight, and cats generally cope very well afterwards. Just as important, though, is diagnosing and treating whatever underlying disease caused it. Even cats that go blind from untreated cataracts often adapt remarkably well in a familiar, safe home — using whiskers, hearing and memory to navigate — but early veterinary care gives the best chance of keeping both the eye comfortable and the vision intact.