Cataracts are whitish or cloudy patches in the lens of the eye that cause it to become opaque and less able to focus light onto the retina. The lens is the clear, crystalline part of the eye through which light passes to reach the retina behind it. Some of the causes of cataracts include:
Age – Age-related cataracts are the most common type of cataract. As people grow older, the proteins within the lens begin to change, which can cause cloudy patches to develop. Researchers believe this may be due to the protein changes altering how fluids and nutrients reach the eye.
Family history of cataracts – People with family members who have had cataracts are at an increased risk of developing them.
Exposure to radiation also raises the risk of cataracts. For example, glassblowers who are exposed to infrared radiation are at a greater risk. Long-term exposure to bright sunlight and ultraviolet radiation has been linked to the development of cataracts in people who work outdoors without wearing eye protective gear.
Certain medications taken over a long period of time can cause cataracts, the most common of which is corticosteroids. The long-term intake of the cholesterol-lowering drug ezetimibe also raises the risk of cataracts.
People with diabetes are nearly twice as likely to develop cataracts as those without the condition.
Some congenital conditions may lead to cataracts in newborns. Some examples include Alport's syndrome, Cri-du-chat syndrome, Patau's syndrome, Trisomy 18 (Edward's syndrome) and Turner's syndrome.
Previous eye inflammation or injury and lifestyle factors such as poor diet and smoking are also some of the causes of cataracts.
Reviewed by Sally Robertson, BSc