Indo-American discovers clue to cataract

WASHINGTON, April 21, 2008

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 per cent of the eye lens and 90 per cent 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 start 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 per cent, thus significantly decreasing vision care cost. Currently, 1.5 million to 2 million cataract surgeries are completed yearly, Sharma said.

Cataract affects 42 per cent of the population aged between 70 and 80 and 68 per cent 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.