In the United States, at least 60% of the population wears corrective lenses. Worldwide, in contrast, only 5% of the population does. Such statistics have led Josh Silver, Oxford atomic physicist, to conclude that more than half the world needs vision correction but doesn't have access to it. In this audio lecture, host of the Center for Social Innovation at Stanford, Silver shares how he decided to "do something useful for the world" by creating specialized, liquid-filled corrective lenses that are now worn by some 26,000 people in developing countries.