Retinopathy of prematurity is a potentially blinding eye disease occurring in babies born before full term. Premature babies often have difficulty breathing and to help them they are put on a ventilator. However, the oxygen concentrations they receive are variable (despite best efforts to control it) and this group has shown that the more severe forms of retinopathy are related to varying oxygen content in the babies’ blood during the first two weeks of life, and they wish to investigate why. Greater understanding of how oxygen levels can interrupt normal eye development should lead to new treatments and ultimately the prevention of such cases of blindness.