Objective: To present ophthalmological outcome data at 5 1/2 years after full term from a natural history cohort of infants who had a birth weight less than 1251 g and were enrolled at 5 centers of the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity (ROP), including eyes without ROP and with a full range of ROP severity. Design: Of the 1199 surviving children in the cohort, 1068 (89.1%) were examined. Study-certified ophthalmologists assessed ROP residua and conducted cycloplegic refractions. Visual acuity was measured by study-trained testers using the Early Treatment for Diabetic Retinopathy Study charts. Eyes that had developed ROP were categorized by the lowest (most posterior) zone and highest (most severe) stage reached during the acute phase of the disease. No eyes that received cryotherapy are included; data analysis included one untreated eye per patient. Fundus outcomes were classified as "unfavorable" if there was macular compromise by retinal folding (more severe than ectopia) or stage 4B or 5 retinal detachment. Visual acuity outcomes of 20/200 or worse were classified as unfavorable. Results: Unfavorable fundus structural outcome occurred in 33 (3.1%) of the 1068 eyes; all 33 eyes had a history of severe ROP. Specifically, unfavorable fundus structure occurred in 62.5% (10/16) of eyes with zone I ROP and in 44.2% (23/52) of eyes with zone II ROP, stage 3+ disease involving more than six 30°-sectors. There were no unfavorable fundus outcomes among eyes that had fewer than 7 clock-hours of stage 3+ ROP in zone II in this cohort. Snellen visual acuity was tested in 1059 eyes, and 5.1% were unfavorable at 20/200 or worse; these unfavorable outcomes were correlated with more severe ROP. In eyes that had zone I ROP, 68.8% (11/16) had unfavorable acuity, and for eyes that had zone II ROP, 7.5% (36/481) had unfavorable acuity results. For eyes with ROP observed only in zone III, 1.8% (2/110) had unfavorable acuity of 20/200 or worse. Conclusions: Premature infants with birth weights less than 1251 g seldom have poor structural and functional outcomes (3.1% and 5.1%, respectively). All unfavorable fundus structural outcomes and nearly all unfavorable acuity outcomes occurred in eyes with zone I ROP or zone II ROP involving more than 6 sectors of stage 3+ disease.