A cataract is a cloudiness of the normally transparent lens. The lens is inside the eye behind the iris, or colored part of the eye. The pupil will open and close over top the lens. The job of the lens is to focus light onto the retina in the back of your eye. The retina will convert that light to a nerve signal and send it the brain to be processed. When your lens becomes cloudy, the images projected to the retina are blurry and unfocused. Therefore the signal to the brain is also unclear. An example would be equivalent to your view of the world through a dirty window.
Usually the changes in cloudiness occurring in the lens develop slowly. Therefore, your decline in vision is so gradual, you may not perceive the change. The majority of the time these changes occur due to the aging process. However, there are certain health concerns, such as diabetes as well as trauma, that can cause these changes to occur earlier in life. Finally, there are also congenital cataracts, which are thankfully much more rare.
While you may be able to tolerate mild cataract changes, moderate to severe changes are treated with surgery. The procedure involves removing the clouded lens, and replacing it with an intra-ocular lens, or IOL. Cataract surgery is a very common procedure that has a high success rate of restoring excellent vision. The procedure is done on an outpatient bases, with both eyes usually completed 1 to 2 weeks apart.
