Caroline Harper: What if we eliminated one of the world's oldest diseases?

Thousands of years ago, ancient Nubians drew pictures on tomb walls of a terrible disease that turns the eyelids inside out and causes blindness. This disease, trachoma, is still a scourge in many parts of the world today — but it's also completely preventable, says Caroline Harper. Armed with data from a global mapping project, Harper's organization Sightsavers has a plan: to focus on countries where funding gaps stand in the way of eliminating the disease and ramp up efforts where the need is most severe. Learn more about their goal of consigning trachoma to the history books — and how you can help. (This ambitious plan is one of the first ideas of The Audacious Project, TED's new initiative to inspire global change.)