Cataracts are caused by build-up of proteins in the lens. Sometimes the protein deposits are small and don’t affect your vision, but larger cataracts can block the smooth flow of light. There are several reasons why a cataract might develop. Ageing is a common cause, but cataracts can also form as a result of trauma. They can develop many years after an eye injury.
Diabetes is also a common cause; people with diabetes are 60% more likely to develop cataracts. Raised glucose levels can lead to swelling, affecting vision, and the lens has an enzyme that converts glucose into sorbitol which can cause a build-up of protein.
While age-related cataracts are very common, there are some instances of congenital cataracts, whether inherited or from infection. High blood pressure, smoking and excessive alcohol consumption can also increase the risk of cataracts.