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12-02-2008, 05:08 PM
How do Age-Related Cataracts Form?

There are two major ways in which age-related cataracts form. Protein clumping and yellowing of the lenses.
In the healthy eye, the lens is mainly made up of water and a protein called crystallins. These proteins are thought to act somewhat like filters allowing the light to enter into the eye and become focused on the retina. There is little time for repair to the lenses as they are in almost constant use. As an individual grows older, some of the protein found in the lenses begins to degenerate and clump, or gather, together. The gathering of this material blocks some of the light that would normally enter through the lens and hit the back of the eye, the retina.
A small amount of protein clumping may not affect the individual's vision noticeably. However, when enough protein clumps in one area, the amount of light entering the eye is decreased and the eyesight becomes progressively more blurry and cloudy. The majority of age-related cataracts are formed in this manner. The current theory is that the protein of the lenses is damaged by free radicals which in turn causes the proteins to clump. Free radicals can be neutralized with antioxidants but many people have too few of these in their bodies to control the free radical assaults. Antioxidants are found mainly in fresh fruits and vegetables.
The second method by which age-associated cataracts form is the result of a yellowing or browning of the normally clear, transparent lens. The discoloration of the lens is a common occurrence in most of the population as age increases and is usually the result of a breakdown of lens proteins which leave behind a yellow-brown pigment. The pigment tends to aggregate together and cloud the region of the lens.
Unfortunately, in some individuals the discoloration of the lens may cause everyday tasks to become more complicated. Those who suffer from cataracts of this type tend to lose the ability to distinguish the colors of blue and purple. This category of cataracts does not seem to cause blurring of shapes.
Some researchers have also pointed to the possibility that age-related cataracts may form due to low serum calcium levels. Nonetheless, in many cases, age-related cataracts have no identifiable cause.