Retinopathy of prematurity (ROP) is a disease of abnormal retinal vascular development that occurs in premature infants and infants of low birth weight. At premature birth, the development of the newborn's retinal vasculature is not yet complete and abnormal growth of blood vessels can occur in the following weeks to months. This change in vascular development is a result of a complex interplay of immaturity, severity of systemic illness, and the relatively increased oxygen levels of the infant's extrauterine environment. Over many weeks, ROP may regress spontaneously or can worsen in severity. Severe ROP, left untreated, can have a devastating impact on the retina and subsequent vision. With standard criteria for screening and prompt treatment of high-risk disease, the impact of ROP has been drastically reduced since it was first described in 1942. Despite these advances, ROP still remains a leading cause of blindness of children in developed countries. As premature infant survival rates have also improved in developing countries, rates of ROP and resulting visual loss has simultaneously risen dramatically. Each year in the US, 1300 children are affected by vision loss, and 500 children affected by severe visual impairment due to ROP. The past 10 years has seen refinements in treatment criteria and the successful use of vascular endothelial growth factor (VEGF)-binding agents such as bevacizumab (Avastin).