A cataract is "any opacity which develops in the crystalline lens of the eye or in its envelope". Cataracts develop for a variety of reasons, with the most common factor being the long-term exposure to ultraviolet light. Cataracts can also develop from advanced age or secondary effects of diseases such as diabetes.

Usually a result of denaturation (the conversion of DNA from the double-stranded to the single-stranded state; separation of the strands is most often accomplished by heating) of lens proteins, there is several genetic factors which are also known to play a major role predisposing an individual to cataracts. As mentioned above with advancing age the prevalence of cataracts becomes more dominant. Cataract formation is expected in any individual over the age of 70 (50% of all people between the ages of 65 and 74 & approximately 70% of those over 75).

Although not as commong, cataracts can be produced as a result of an eye injury or other physical trauma. A recent study of Icelandair pilots, proved that commercial airline pilots are three times as likely to develop cataracts as people with non-flying jobs. This increase in odds isn't completely known yet, but is thought to be caused by radiation coming from outer space. Cataracts is most commonly aided via surgery called cataract surgery. The surgery aims to restore the eye back to it's original state by removing any cataracts that are present.

We're only given one set of two eyes. Taking care of them is extremely important. This can mean simple precautions such as wearing sunglasses to prevent our eyes from elements such as ultraviolet light, wind, and from getting particles in the eye that can damage or lenses.