Clue to cataract formation discovered

April 21st, 2008 - 3:06 pm ICT by admin  


Washington, April 21 (IANS) An Indian-American scientist has identified how a specific kind of protein is likely to be behind the formation of cataract. K. Krishna Sharma of Missouri University has found that as this protein becomes inactive, small peptides, made of 10 to 15 amino acids, start forming and accelerate cataract formation.

Proteins make up about 50 percent of the eye lens and 90 percent of these proteins are crystallins. They maintain the clarity of the lens through an activity known as “chaperoning”.

In a healthy eye, crystallins break down over time, degrading into small peptides. The peptides are then cleared from the eye with the help of other proteins.

As the eye ages, small peptides start to form at an increasing rate. Chaperone activity starts to decrease, resulting in less cleansing activity inside the lens.

As the small peptides increase, the eye’s lens starts to develop cataracts. There are a variety of causes that lead to the decrease of chaperone activity, and the presence of these small peptides accelerates the process, Sharma said.

“It is very helpful to track the formation of these peptides,” Sharma said. “The next step is to work on preventing their formation. If we are successful, we could delay the aging process in the eye.”

A 10-year delay in the onset of cataracts could decrease the number of cataract surgeries by 45 percent, thus significantly decreasing vision care cost. Currently, 1.5 million to 2 million cataract surgeries are completed yearly, Sharma said.

Cataract affects 42 percent of the population aged between 70 and 80 and 68 percent of those aged over 80, according to the National Eye Institute.

This discovery has been published in a recent issue of The Journal of Biological Chemistry.

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