What is a cataract?

A cataract is an area of opaqueness in the lens of the eye (which is normally transparent) that leads to a decrease in vision. Cataracts are usually bilateral (affect both eyes), although they may affect each eye differently and usually they progress slowly over many years.

However, these symptoms start slowly, and most people often mistake them for other ‘age-related’ changes. Cataracts are most commonly due to ageing but may also occur due to trauma, due to use of medications, be present from birth, or occur following eye surgery. Cataracts cause half of all cases of blindness and 33% of visual impairment worldwide; in all about 20 million people worldwide are blind due to cataracts.