Globally at least 50,000 children are blind from retinopathy of prematurity (ROP) which is now a significant cause of blindness in many middle income countries in Latin American and Eastern Europe. Retinopathy of prematurity is also being reported from the emerging economies of India and China. The characteristics of babies developing severe disease varies, with babies in middle and low income countries having a much wider range of birth weights and gestational ages than is currently the case in industrialized countries. Rates of disease requiring treatment also tend to be higher in middle and low income countries suggesting that babies are being exposed to risk factors which are, to a large extent, being controlled in industrialised countries. The reasons for this "third epidemic" of ROP are discussed as well as strategies for control, including the need for locally relevant, evidence based criteria which ensure that all babies at risk are examined.