Retinopathy of prematurity in infants born before 25 weeks gestation in a Korean single neonatal intensive care unit: incidence, natural history and risk factors.

As younger preterm infants are able to survive, more extremely preterm infants are at risk of developing retinopathy of prematurity (ROP). To investigate the incidence, progression and risk factors of ROP in extremely preterm infants in Korea, the medical records of infants born before 25 weeks gestation were retrospectively reviewed. The criteria for laser treatment agreed with type 1 ROP as defined by the Early Treatment for Retinopathy of Prematurity study. Of the 121 infants included in the analysis, 119 (98.4%) infants developed any stage ROP, including 78 infants (64.5%) with type 1 ROP. The mean postmenstrual age (PMA) at the onset of any ROP and type 1 ROP were 33.5 and 36.1 weeks, respectively. All but one infant developed type 1 ROP after 31 weeks PMA. Univariate analysis showed that duration of total parenteral nutrition and onset of any ROP (PMA) were associated with the development of type 1 ROP. In conclusion, this study shows high incidence of ROP in extremely preterm infants and suggests that, although current screening protocols are feasible for most preterm infants born before 25 weeks gestation, earlier screening before 31 weeks PMA may be necessary in infants with an unstable clinical course.