Retinopathy of prematurity (ROP) is the cessation of normal eye development and subsequent abnormal vessel growth that occurs exclusively in premature infants. ROP was first discovered in the 1940s and was for two decades the leading cause of blindness in children. Currently, the disease causes about 500 new cases of blindness per year. The severity of the disease increases with decreasing gestational age. The pathogenesis of ROP involves disruption of normal retinal vascularization. Vessel endothelial growth factor, insulin-like growth factor, and oxygen play important roles in its development. ROP is classified using an international classification system that provides direction for screening and treatment of premature infants. Examinations are performed by ophthalmologists, who identify the scope of vascularization, the degree of abnormal vessel growth, and the amount of the eye that is affected. Treatment modalities include cryosurgery and laser photocoagulation. Long-term outcomes include both structural and functional vision problems.