Characteristics of posterior zone I retinopathy of prematurity

Objective: To report the demographic profile and clinical characteristics of retinopathy of prematurity (ROP) in posterior Zone I. Methods: In a partly retrospective (ten years) and partly prospective (one year) study, we analysed the demographic profile and clinical characteristics of babies with ROP in posterior Zone I. Results: The study included 130 eyes of 67 infants with a mean gestational age and birth weight of 29.3 (±2.2) weeks and 1217.3 (±381.9) grams, respectively. All babies had received unblended oxygen. In 47 of 51 (91.1%) babies, the weekly weight gain was <100 g (details were not available in 16 babies). The ROP subtypes included aggressive, threshold, hybrid, stage 4, and atypical types in 78 (60%), 20 (15.4%), 11 (8.5%), 15 (11.5%), and 6 (4.6%) eyes, respectively. Fibrovascular proliferation, when present, was prominent nasally, occasionally overriding the disc margin. Extensive arteriovenous tortuosity was more prominent than vascular dilatation. Atypical observations included bleb-like detachment (6 eyes; 4.6%) and candle wax-like preretinal deposits (23 eyes; 17.7%). Conclusions: Retinopathy of Prematurity in posterior Zone I in this cohort was strongly associated with 100% unblended oxygen supplementation, poor weight gain, and multiple systemic co-morbidities. ROP in posterior zone 1 has a distinct profile with several atypical characteristics different from ROP in other zones.