Results of the Treatment of Zone I versus Zone Ii Retinopathy of Prematurity

Zone I retinopathy of prematurity (ROP) generally has a poorer prognosis than zone II ROP. The aim of this study was to evaluate the effect of early ROP treatment on the pathological findings on the retina at 6 months of age in relation to the extent of disorder. Preterm infants weighing less than 1500 g at birth were examined before 4 weeks of age. A total of 139 eyes in 93 infants were identified to have avascular retina. Of them, 56 eyes (39 infants) had zone I ROP (group I) and 83 (54 infants) had zone II ROP (group II). Therapy included transpupillary indirect diode-laser photocoagulation and/or trans-scleral cryotherapy. At 6 months of follow-up, the structural outcomes of treatment were assessed according to the Cryotherapy for Retinopathy Criteria and were compared between the groups. In Group I, 19 (33%) eyes had an unfavourable structural outcome while, in group II, it was 11 (13.2%) eyes (P = 0.027). The mean birth weight and gestational age were similar in both groups, but the mean gestational age at treatment was significantly different (32.1 ± 3.4 weeks in group I vs. 36.5 ± 3.7 weeks in group II, P = 0.013). It is concluded that a higher amount of unfavourable anatomic results in zone I ROP may indicate a poorer prognosis for useful vision in these infants. Special attention should be paid to atypical fundus changes in zone I ROP in order to begin treatment as early as possible.