A cataract is a painless clouding of the lens of the eye. The lens is naturally clear and is located in the area of the pupil and behind the iris or colored part of the eye. Its job, along with the cornea, is to take in light rays and bring them into sharp focus on the retina.
With cataracts, instead of being clear like cellophane the lens becomes more and more like waxed paper. In fact, the word cataract is another name for "waterfall," since, with a very mature cataract, the pupil will appear white in color.
According to the American Academy of Ophthalmology, 70% of all people over the age of 75 develop cataracts, and the World Health Organization states that cataracts are the leading cause of blindness globally, affecting millions of people. Yet their treatment is also one of the simplest and most successful surgical procedures.
The chief cause of cataracts is aging. To a biochemist aging is an oxidation process, so cataract formation is an oxidation reaction of the natural proteins of the lens, called albumin. Interestingly, the white of an egg is also made of albumin and, with the oxidative help from the heat of a stove top, it will turn from clear to opaque-white right before your eyes. Aging does take us slowly down the path to cataracts, as does exposure to ultraviolet light. This is why cataracts are more common in those people who are outside a lot (sailors, surfers, painters, those in agriculture, etc.), as well as in those who live near the equator where there is just more sunlight.
Unprotected exposure to certain other lights such as a welder’s torch may also cause early cataract formation, along with genetic disposition, smoking, some medications, trauma to the eye, and diseases such as diabetes.
For all these reasons and more, cataract surgery is performed on patients of all ages, from infants, right through mid-life, and on to the elderly. For those with age-related cataracts in the United States, the average age for undergoing surgery is 74.6 years.
Not all cataracts impair vision or affect daily vision. But they can gradually develop to a point where they interfere with a person's quality of life. Because of this gradual onset, we often find that patients aren't aware of the degree to which they struggle because they have grown accustomed to poor vision.
Cataracts are usually treated with surgery if they are interfering with the patient's daily life. Cataract surgery is very common and currently has the highest success rate of any surgical procedure. It involves replacing the clouded lens of the eye with an artificial lens called an Intraocular lens (IOL) implant.