London, Nov 27 (IANS): The age-related long-sightedness could be due to proteins in eye-lens that are converted from a fluid solution to a solid glassy state, making the lens more rigid, says a study.

Around the age of 40-50, many people find their sight deteriorates and they need to use reading glasses. This age-related long-sightedness is thought to be due to a reduction in the elasticity of the lens in the eye.

"This feels like an exciting discovery," said Anna Stradner, associate professor at Lund University in Sweden.

The researchers focused on the protein that occurs most commonly in the lens of the eye, alpha-crystallin.

They found that, at high concentrations, solutions of this protein undergo a transition from a fluid form to a glassy state as it becomes less mobile.

This could be the reason why eye-lens becomes more rigid with age.

The study also suggests a link to another eye condition, cataract, in which the lens becomes cloudy.

The researchers believe that cataract formation may be influenced by the reduced movement of the protein in the lens when the glassy state occurs.

The study appeared in the scientific journal Proceedings of the National Academy of Sciences.