myopia (most common) strabismus amblyopia retinal detachment, traction of the retina and blindness glaucoma impairments in visual acuity, contrast sensitivity, visual field, convergence, and accommodation epidemiology rop prevalence varies, from 5 to 8% in developed countries with adequate neonatological facilities, to up to 30% in middle-income developing countries. there is increasing evidence that rop and blindness due to rop are now public health problems in the middle income countries of latin america, eastern europe and the more advanced economies in south east asia and the middle east region. in these countries rop is often the most common cause of blindness in children. rop is highly likely to become an increasing problem in india, china and other countries in asia as these countries expand the provision of services for premature infants. there is also evidence that the population of premature infants at risk of severe rop varies depending on the level of neonatal intensive care being provided. in countries with high development indices and very low neonatal mortality rates (e.g. north america, western europe), severe rop is generally limited to extremely preterm infants i.e. those weighing less than 1 kg (2.2 lbs) at birth. at the other end of the development spectrum, countries with very low development indices and very high neonatal mortality rates (e.g. much of subsaharan africa) rop is rare as most premature babies do not have access to neonatal intensive care and so do not survive. countries with moderate development indices are improving access to neonatal intensive care, and in these settings bigger, more mature babies are also at risk of severe rop as neonatal care may be suboptimal. these findings have two main implications: firstly, much can be done in countries with moderate development indices to improve neonatal care, to reduce the risk of severe rop in bigger babies and increase survival of extremely preterm infants, and secondly, in these settings bigger more mature babies need to be included in rop programs and examined regularly so as to detect those babies developing rop requiring treatment. in 2012, the world health organization published data on rates of preterm birth and the number of premature babies born in different regions of the world. this report contained three main findings: premature birth has many different causes, and prevention is challenging, prematurity is the most common cause of neonatal death in many countries, totaling as many as 1 million infants annually due to complications of preterm birth, and the number of preterm births is currently estimated to be 15 million, and increasing. history this disease was first described in a premature baby in 1942 as reported by theodore l. terry. between 1941 and 1953, over 12,000 babies worldwide were affected by it. however, dr kate isabel campbell (1889-1986), a specialist in children's diseases, was actually responsible in 1951 for proving the link between retrolental fibroplasia (a blindness in premature babies) and oxygen levels in humidicribs. soul musician stevie wonder, actor tom sullivan, and jazz singer diane schuur are a few famous people who have the disease. the first case of the epidemic was seen on st. valentine's day in 1941 when a premature baby in boston was diagnosed. cases were then seen all over the world and the cause was, at that point, unknown. by 1951 a clear link between incidence and affluence became clear: many cases were seen in developed countries with organized and well-funded health care. two british scientists suggested that it was oxygen toxicity that caused the disease. babies born prematurely in such affluent areas were treated in incubators which had artificially high levels of oxygen. studies on rats made this cause seem more likely, but the link was eventually confirmed by a controversial study undertaken by american pediatricians. the study involved two groups of babies. some given the usual oxygen concentrations in their incubators, while the other group had "curtailed" oxygen levels. the latter group was shown to have a lower incidence of the disease. as a result, oxygen levels in incubators were lowered and consequently, the epidemic was halted.