Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is abnormal retinal blood-vessel growth in an immature eye. Retinal vessels normally grow outward from the optic disc toward the peripheral retina during late gestation. When birth occurs before that process is complete, peripheral retina remains avascular. ROP develops through a two-phase process. After premature birth, exposure to extrauterine oxygen—especially excessive oxygen or large oxygen fluctuations—can suppress normal vessel growth and cause regression of fragile vessels. The remaining avascular retina continues to mature and has increasing metabolic needs. In the second phase, relative retinal hypoxia stimulates vascular endothelial growth factor (VEGF). New vessels grow abnormally rather than extending in an orderly pattern. These abnormal vessels are fragile and can bleed. Fibrovascular tissue may contract, pulling on the retina and causing partial or total retinal detachment. Vision loss is the late consequence; the early disease is usually invisible to the bedside observer. That is why a clinically stable infant with normal-appearing eyes can still require a time-sensitive retinal examination. Oxygen is therefore a management balance, not an intervention to eliminate. The infant must receive enough oxygen for...