What are cataracts?
A cataract is defined as clouding or loss of transparency in the lens of the eye that interferes with vision. Cataracts usually develop as a result of normal aging and are most prevalent in people over 40, with half of all people in the U.S. developing cataracts by the age of 80 (Source: NEI).
The lens is formed of water and special proteins that are initially clear. Cataracts develop when proteins of the lens begin to cluster and become denser. The formation of these protein bundles makes it difficult for light to pass through the eye to the retina and creates a discolored or opaque area in the lens.
Less commonly, cataracts may occur at any age as a result of injury to the lens. In some cases, cataracts are congenital, which means they are present at birth. Cataracts may also develop as a result of diabetes or extended use of certain medications, including corticosteroids. Cataracts due to aging, disease, or drugs tend to occur in both eyes, although the degree of severity may be different in the two eyes. A cataract caused by trauma will affect only the injured eye.
Cataracts generally develop over time and may get progressively worse as you age. In most cases, you most likely will not experience any symptoms until the cataract is advanced. Symptoms include gradually increasing haziness of vision and glare or halos from lights. Cataracts are not treated until they cause visual symptoms. Fortunately, cataract surgery is highly successful in restoring clear sight.
Cataracts generally do not indicate a medical condition that needs immediate attention. However, they can be a sign of chronic serious conditions such as diabetes. Seek prompt medical care if you have symptoms of cataracts that become bothersome or are associated with other symptoms.
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- Facts about cataract. National Eye Institute. http://www.nei.nih.gov/health/cataract/cataract_facts.asp.
- Cataracts. JAMA Patient Page. http://jama.ama-assn.org/content/301/19/2060.full.pdf.
- Tierney LM Jr., Saint S, Whooley MA (Eds.) Current Essentials of Medicine (4th ed.). New York: McGraw-Hill, 2011.