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The lens of the eye focuses light, so that you can see objects clearly at different distances. It must remain transparent for clear vision. The lens is mostly made up of water and protein, in a precise composition to keep the lens clear and allow light to pass through. With age, changes in the chemical composition of the lens occur: parts of the protein may clump together and start to cloud a small area of the lens. This is how most cataracts are formed. Over time, the cataract may grow larger and cloud more of the lens. As the developing cataract blocks or distorts light entering the eye, those affected will experience a gradual, persistent and painless blurring of vision.
The following are causes of cataracts:
• Cataracts are associated with ageing and are common in older adults. About 75 percent of all cataracts are age-related.
• Exposure to ultraviolet (UV) radiation (e.g. from sunlight).
• Eye injuries. Sharp or blunt injuries may cause a cataract.
• Diabetes, especially when blood sugar is poorly controlled.
• Cataracts may develop as a secondary effect of other eye ailments, such as glaucoma (raised pressure within the eye) or uveitis (inflammation in the eye).
• Long-term use of certain medications, most notably steroids, may cause cataracts.
• Radiation treatment to the head or even when struck by lightning or electrocution.
• Some babies are born with cataracts (congenital cataracts) or develop cataracts shortly after birth.
• Hereditary factors.
