Despite progress during the past decade in treatment of ROP, this disease still poses a significant (approximately 2.1 percent) risk of blindness to extremely low birth-weight (<1,251 grams) preterm infants. Current estimates indicate that about 27,000 infants of extremely low birth weight are born annually, of which 74 percent will survive. As techniques of managing smaller and less mature preterm infants continue to improve, it is expected that the number of infants at risk for blindness will continue to increase.