All infants with birth weight ≤1500 g or born at <32 weeks are screened.
In addition, selected infants born at >32 weeks gestational age deemed at risk
(complicated clinical course). Infants are screened when they are 4-6 weeks
chronological age, or 31-33 weeks postconceptual age.
ROP is classified by the clinical stage and the retinal zone.
Retinal Zones
Zone 1: Vessels extend less than twice the distance between the disc and macula. A
very immature retina with great potential for severe disease.
Zone 2: Vessels extend further, but potential for severe disease still exists.
Zone 3: Vessels are quite mature. There is a small risk for severe disease.
ZONE 3ZONE1ZONE 2O 31269
MACULAOPTIC N.