Ranibizumab injection and laser photocoagulation to treat type 1 retinopathy of prematurity after 40 weeks post menstrual age: a retrospective case series study

BACKGROUND: Type 1 retinopathy of prematurity (ROP) is occasionally observed in preterm infants after the postmenstrual age (PMA) of 40 weeks; however, evidence-based treatment guidelines are largely lacking. In this study, we report the clinical characteristics of preterm infants with type 1 ROP at PMA of > 40 weeks and compare the treatment outcomes of intravitreal ranibizumab (IVR) and laser therapy. METHODS: Twenty-seven eyes of 14 infants, primarily treated for type 1 ROP after 40 weeks PMA by IVR (17 eyes in 9 infants) or by laser photocoagulation (10 eyes in 5 infants) were included in this retrospective analysis. The preoperative fundus characteristics and the structural outcomes and additional treatment after 6 months were analyzed. RESULTS: Of the 27 eyes, 20 eyes (74%) had zone II stage 3 plus disease (+) ROP and 7 eyes had zone II stage 2 + ROP. Seventeen (63%) eyes showed thick fibrous ridges. After primary treatment at 40–48 weeks PMA, ROP regression was observed in a similar proportion of eyes in the IVR and laser groups (88% vs. 70%; p = 0.326); complete vascularization was observed in 24% eyes in the IVR group. Compared to laser group, a higher proportion of eyes in IVR group received additional treatment (IVR group 76% vs. laser group 30%; p = 0.040), for unresolved peripheral avascularity in 11 eyes and ROP progression with fibrotic contraction in 2 eyes after primary IVR. CONCLUSION: Preterm infants with type 1 ROP at > 40 weeks PMA displayed enhanced fibrotic proliferation. Both primary IVR and laser effectively promote ROP regression. Primary IVR cannot guarantee full retinal vascularization but is associated with a risk of fibrotic contraction.