A cataract is clouding of a part of the eye called the lens. The vision becomes blurred or dim because light cannot pass through the clouded lens to the back of the eye. Over half of those over 65 have some cataract development and most cases can be treated successfully with surgery. The lens is a transparent body behind the iris, the colored part of the eye. The lens bends light rays so that they give a clear image to the back of the eye - the retina.
Cataract can form at any age, but most often it develops as people get older.
In younger people they can result from an injury, certain drugs, long-standing inflammation or illness such as diabetes. The most effective treatment for cataracts is an operation to remove the cloudy lens and replacing it with a plastic intraocular lens implant. After removing the cloudy lens surgically, it is usually replaced by a plastic lens so that the eye can focus properly. Occasionally a doctor will decide whether someone's eye is suitable for a lens implant. In these cases not suitable for implant special glasses are prescribed instead.