New York, Nov 6 (IANS): A team of scientists has identified a new chemical that can be used in eye drops to reverse cataracts which are a leading cause of blindness worldwide.

The newly identified compound is the first that is soluble enough to potentially form the basis of a practical eye-drop medication for cataracts.

The team of scientists from University Of California-San Francisco (UCSF), the University of Michigan (U-M), and Washington University in St. Louis (WUSTL) began with 2,450 compounds, eventually zeroing in on 12 that are members of a chemical class known as sterols.

One of these, known as lanosterol, was shown to reverse cataracts, but because lanosterol has limited solubility the compound had to be injected into the eye for it to exert its effects.

Using lanosterol and other sterols as a clue, the group assembled and tested 32 additional sterols, and eventually settled on one, which they call "compound 29", as the most likely candidate that would be sufficiently soluble to be used in cataract-dissolving eye drops.

The team next tested compound 29 in an eye-drop formulation in mice carrying mutations that make them predisposed to cataracts.

They found that the drops partially restored transparency to mouse lenses affected by cataracts, as measured by a slit-lamp test of the sort used by ophthalmologists to measure cataracts in humans.

Similar results were seen when compound 29 eye drops were applied in mice that naturally developed age-related cataracts, and also when the compound was applied to human lens tissue affected by cataracts that had been removed during surgery.

Identified as a "priority eye disease" by the World Health Organisation, cataracts -- caused when the lenses of the eyes lose their transparency -- affect more than 20 million people worldwide.

The study was published in the journal Science.