Towards evidence based public health

eaders of the BJO will be aware that cataract is the leading cause of blindness in Africa, affecting an estimated half of the seven million blind people in that continent.1 This number is likely to increase substantially, as approximately 600 000 Africans become blind from cataract each year. Despite the enormity of the problem, few cataract operations are performed in Africa. The cataract surgery rate (CSR), a measure of the volume of cataract surgery performed in a population, is about 500 per million per year in Africa. To tackle cataract blindness, the Visio