This study was a randomized trial comparing the effects of 2 oxygenation strategies on the progression of ROP. Infants with prethreshold ROP in at least one eye were eligible for the study. Enrolled infants were randomized to receive either conventional oxygenation at a pulse oximetry target of 89% to 94%, or supplemental oxygen to achieve a pulse oximetry target range of 96% to 99%. Infant were placed on continuous pulse oximetry monitoring and to maintain oxygen saturation, as much as possible, in the assigned target range.