A clouding of the eye's natural lens

A cataract is a clouding of the eye's natural lens.

The lens becomes opaque or cloudy, resulting in blurred vision.

A cataract can form in one or both eyes.

Symptoms

When a cataract is present, the eyes may be more sensitive to glare and light, and colours may seem faded or yellow.

Double vision might also occur.

Other symptoms include glare and sensitivity to bright light, or haloes which may appear around lights. Haloes are especially noticeable when driving at night and, at the same time, night vision typically decreases.

Causes of cataract

Ageing

Cataracts are very common in older people, and develop as a normal part of ageing.

By the age of 60, about half of all adults have some cataract formation (albeit minor). By the age of 70, nearly everyone has some form of cataract formation.

Diabetes

Adults with diabetes are 2 to 5 times more likely to develop cataracts than people with diabetes.

Other causes

Other causes of cataract include various eye diseases, eye injury or excessive ultraviolet light. Cataracts usually develop slowly, and at a different rate, within each eye. Some years may pass before the cataract interferes enough with vision for a person to seek advice from an eye specialist.