Importance of Birth Weight as a Risk Factor for Severe Retinopathy of Prematurity When Gestational Age Is 30 or More Weeks

Purpose To determine whether birth weight less than 1500 g is a relevant guideline indicating the need for examination for retinopathy of prematurity (ROP) when gestational age at birth is 30 or more completed weeks. Design A retrospective observational cohort study. Methods A total of 266 infants in a single institutional neonatal intensive care unit (NICU), whose gestational age at birth was 30 or more weeks but whose birth weight was less than 1500 g, were examined according to published guidelines. Infants with lethal congenital anomalies or major ocular abnormalities were excluded. Outcomes were vascularization in retinal zone III without a prior need for treatment, or ROP warranting treatment. Results A study outcome was reached by 212 infants. Two hundred and eleven (99.5%) became vascularized through zone III without needing treatment. Only 1 (0.5%) required treatment for ROP. The 95% confidence interval for the occurrence rate of ROP requiring treatment in this cohort was 0.01%-2.60%. Conclusion Our results suggest that the occurrence rates of ROP requiring treatment in infants with gestational age 30 or more weeks and birth weight less than 1500 g is very low, and could indicate the need to revise examination guidelines for this subgroup of infants.