World Leaders on Monday are holding their first-ever U.N. meeting to explore how the more than 1 billion disabled people in the world can contribute to their global economy instead of being a drain on societies. The World Health Organization (WHO) says a huge increase in hearing aids, eyeglasses, and wheelchairs could improve the lives of hundreds of millions of people and help them participate in the development of their countries. But the disabled have other obstacles to overcome, including discrimination and stigmas, the agency said. The high-level General Assembly meeting on disabilities is the prelude to the annual U.N. gathering of world leaders, which begins Tuesday.