Each enrolled infant underwent dilated fundus examination with indirect ophthalmoscopy and digital imaging of the fundus at an examination between 31 and 34 weeks of PCA. Bedside examinations were performed by an attending pediatric ophthalmologist in the neonatal intensive care unit. Digital fundus images were taken with a noncontact camera (model NM200D; NIDEK Co Ltd, Fremont, California). Each infant had as many images taken as could be obtained during the limited amount of time preceding indirect ophthalmoscopy, with an average of 8 images per eye (SD, 3.5). Patients then underwent successive imaging and indirect ophthalmoscopy every 1 to 2 weeks, as clinically indicated according to established protocols,6- 8,31 until the retinal vasculature matured, ROP regressed, or serious ROP was treated. The maximum stage of ROP and treatment status for each eye were recorded, and eyes were classified into 2 groups. One group contained eyes with severe ROP requiring treatment, meeting the following criteria: (1) any stage, zone 1 or 2, with plus disease, (2) stage 3, zone 1 or 2, with pre–plus disease, or (3) stage 2, zone 1 or 2, with pre–plus disease and the paired eye meeting criterion 1 or 2. The other group included eyes with less severe ROP (stage 1, 2, or 3 with neither plus disease nor a paired eye reaching treatment threshold) and eyes with no ROP, none of which required treatment.