Predictors and Individualized Treatment of Retinopathy of Prematurity Reactivation Following Intravitreal Ranibizumab

AIM To explore the predictors of reactivation in retinopathy of prematurity (ROP) after intravitreal ranibizumab (IVR) and evaluate the effectiveness of individualized treatment strategies for managing reactivation cases. METHODS This retrospective case series included infants diagnosed with type 1 ROP or aggressive ROP (AROP) who received initial IVR between October 2019 and October 2023. Data on the timing of reactivation after the first injection and associated risk factors were collected. Additional outcomes, including the occurrence of adverse events and reactivation rates following a second IVR, were also assessed. A decision tree model was used to identify the predictors of reactivation. In cases of reactivation occurring 1 to 3 months post-IVR, re-injection was administered if peripheral retinal vascular growth > 1 papillary diameter (PD); otherwise, laser photocoagulation (LP) treatment was employed. RESULTS A total of 88 infants (166 eyes) with type 1 ROP or AROP received initial IVR. Reactivation occurred in 19 infants (38 eyes, 22.9%) with a mean reactivation time of 8.8 ± 3.8 weeks. Postmenstrual age (PMA) at the time of surgery, gestational age (GA), and cumulative clock hours (CCH) of ROP were identified as significant predictors by the random forest model, with CCH of ROP > 10 identified as the root node influencing outcomes in the decision tree model. In the re-IVR group, 6 infants (12 eyes, 50%) required additional LP due to a second reactivation, with a mean reactivation time of 15.2 weeks. By the final visit, all cases of reactivation and active disease were successfully resolved, with no severe adverse events reported. CONCLUSION The CCH of ROP, GA, and PMA at the time of surgery were identified as predictive factors for reactivation following initial IVR, with a CCH of ROP > 10 serving as a critical threshold. Individualized treatment strategies, including re-injection based on retinal vascular growth extension > 1 PD within 1 to 3 months post-IVR, led to favorable outcomes in reactivation cases.