A cataract is an eye disease in which the normally clear lens of the eye becomes cloudy or opaque, causing a decrease in vision. The lens focuses light onto the back of the eye (the retina) so images appear clear and without distortion. The clouding of this lens during cataract formation distorts vision. Cataracts are usually a very gradual process of normal aging but can occasionally develop rapidly. They commonly affect both eyes, but it is not uncommon for a cataract in one eye to advance more rapidly. Cataracts are very common, especially among the elderly.
Precisely why cataracts occur is unknown. However, most cataracts appear to be caused by changes in the protein structures within the lens that occur over many years and cause the lens to become cloudy. Rarely, cataracts can present at birth or in early childhood as a result of hereditary enzyme defects, other genetic disease, or systemic congenital infections. Severe trauma to the eye, eye surgery, or intraocularinflammation can also cause cataracts to develop more rapidly. Other factors that may lead to development of cataracts at an earlier age include excessive ultraviolet light exposure, exposure to ionizing radiation,diabetes, smoking, or the use of certain medications, such as oral, topical, or inhaled steroids. Other medications that may be associated with cataracts include the long-term use of statins and phenothiazines.
The total number of people who have cataracts is estimated to increase to 30.1 million by 2020. When people develop cataracts, they begin to have difficulty doing activities they enjoy. Some of the most common complaints include difficulty driving at night, reading, or traveling. These are all activities for which clear vision is essential.
What are the symptoms and signs of cataracts?
Cataract development is like looking through a dirty windshield of a car or smearing grease over the lens of a camera. Cataracts may cause a variety of complaints and visual changes, including blurred vision, difficulty with glare (often with bright sun or automobile headlights while driving at night), dull color vision, increasednearsightedness accompanied by frequent changes in eyeglass prescription, and occasionally, double vision in one eye. A change in glasses may initially help once vision begins to change from a cataract. However, as the cataract continues to become denser, vision also becomes more cloudy, and stronger glasses or contact lenses will no longer improve sight.
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