National Geographic : 2009 Jul
2 Seal with stopper, then remove tube and syringe. 1 Adjust dial to inject or remove oil, changing the shape of the lens to sharpen vision. PHOTO: JOSHUA SILVER ART: HIRAM HENRIQUEZ, NG STAFF TECHNOLOGY The Eyes Have It More than a billion people in the developing world need glasses. But opticians aren't exactly on every block in sub-Saharan Africa. In some places the ratio is one to one million residents. Pondering this problem, Oxford University physics professor Joshua Silver came up with a brilliantly simple solution: a pair of eyeglasses, currently costing about $19, that the wearer can adjust. Silicone oil is injected into a gap between two sheets of plastic until the lens provides sharp vision (right). The inventor's field research shows the correction can be better than that of prefab glasses sold at a store. As director of the new nonprofit Centre for Vision in the Developing World, Silver envisions a billion pairs on needy eyes by 2020. So far, 30,000 pairs are in use in Africa and eastern Europe, two-thirds distributed through U.S. military aid programs. The glasses look a bit geeky, but there are few complaints. Silver recalls the first recipient, in Ghana in 1996: a tailor in his 30s whose faltering close vision made it nearly impossible to thread a needle. The tailor adjusted the glasses, threaded the needle on his machine, and began sewing rapidly. "I will not forget that moment," says Silver, "until I entirely lose my memory." ---Marc Silver This man in a remote Tibetan village received his adaptive glasses in 2005. CORRECT YOURSELF Adaptive eyeglasses can be adjusted for close or distance vision.