Objective To determine the incidence of retinopathy of prematurity (ROP) and its characteristics in a level III neonatal intensive care unit before and after a protocol change in the practice of oxygen supplementation.

Methods A prospective database recorded the gestational age, birthweight, stage and zone of ROP, and date of examination, as well as maternal characteristics and infant morbidity and mortality. Demographics including gestational age, birth weight, zone, stage, threshold disease, treatment and final outcome were recorded. The main outcome measure was the prevalence of ROP, stage and zone of retinopathy, threshold and progression to retinal detachment or fold.

Results 98 infants were examined before and 92 infants were examined after the change in oxygen. ROP was present in 35% of infants in group 1 compared with 13% in the year after the change in oxygen standards (p = 0.001); stage 3 decreased from 11% to 2% (p = 0.021); threshold disease decreased from 7% to 1% (p = 0.066). Stage 0 (immature vessels, no ROP) incidence increased (pre/post oxygen change 30%/51% stage 0), as did zone 3, whereas there was a decrease in less mature zones, (pre/post oxygen change zone 1: 5%/2%; zone 2: 48%/38%; zone 3: 47%/60%). There were no stage 4 or 5 eyes. Co-morbidity comparison (respiratory distress syndrome, periventricular leucomalacia, sepsis, necrotising enterocolitis, patent ductus arteriosus, steroids for chronic liver disease), maternal characteristics (outborn birth, prenatal care, antenatal steroids, C-section, ethnicity) and mortality were not statistically significant between groups.

Conclusion Comparatively lower oxygen targets at early gestational age and higher oxygen limits at older gestational age decrease the severity and prevalence of ROP.