There are several causes. The most common form of cataracts is associated with ageing, although not everyone develops cataracts as they get older.

Cataracts may also be caused by an eye injury such as a sharp blow, a chemical or electrical burn or a very high dose of radiation. Rare causes include side-effects of some long-term medications and eye disease.

Genetics can also rarely lead to the development of cataracts at birth or early childhood.