Professor Joshua Silver has been named as one of the world's top innovators - for developing self-adjustable spectacles.

The invention, which allows the wearer to focus by adjusting a pair of fluid-filled lenses, could enable one fifth of the world's population to see properly.

Earlier this year, the glasses won the physics tutor at New College, Oxford, a special commendation from the British Government in the Worldaware Business Awards.

Now the Adspecs, which will only cost £10 a pair, and will be a boon for people in the Third World, have won a further accolade at the Saatchi & Saatchi Innovation in Communication Award.

At a ceremony in San Francisco at the weekend, creative thinker Edward do Bono presented Prof Silver with the de Bono Medal for the new idea he considered to be the most simple, practical and effective among 11 finalists.

The professor has launched a company Adaptive Eyecare in Mill Street, Oxford, to develop, manufacture and market the glasses.

He said: "I am honoured to have received this accolade. It is especially heartening to have the self-adjustable spectacles recognised so publicly."

The revolutionary lenses that Prof Silver has invented contain a fluid encased in a thin elastic plastic membrane. The lenses are adjusted by changing the pressure on the fluid.

Tests funded by the British Government, the World Health Organisation and several private companies have already been successful in Ghana, Africa.

A sonar system enabling blind people to "see with sound", invented by New Zealand professor Leslie Kay, won the top award.

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