Predictive Factors for Retreatment after Intravitreal Ranibizumab Injection to Treat Type 1 Retinopathy of Prematurity

Purpose: To investigate predictive factors for retreatment after intravitreal ranibizumab injection as first-line treatment for retinopathy of prematurity (ROP).Methods: The medical records of consecutive infants diagnosed with type 1 ROP from 2013 to 2021 who received 0.2 mg intravitreal ranibizumab as their first treatments were retrospectively reviewed. Only eyes with severe ROP were included. Retreatment was performed if eyes again met the criteria for type 1 ROP or presented with stage 3 ROP and the plus sign. Factors around the time of first injection that predicted retreatment were assessed.Results: Intravitreal ranibizumab was injected into 44 eyes of 44 infants. The mean gestational age (GA) and body weight were 27.8 weeks and 1,046.6 g, respectively. Retreatment was required by 21 eyes (47.7%) at an average of 8.9 weeks after the first injection, thus at 37.2 weeks of mean postmenstrual age. The retreatment group exhibited a lower GA (p = 0.036), lower 1 minute (min) (p = 0.014) and 5 min (p = 0.029) Apgar scores, and more quadrants with plus signs (p = 0.044) before the first injections; they also had a longer period of oxygen requirement (p = 0.001), more loss of the plus sign (p = 0.014), and more ROP involution (p = 0.003) after the first injections. The risk of needing retreatment increased with a lower 1 min Apgar score (p = 0.010, odds ratio [OR] = 2.04) and later disappearance of the plus sign (p = 0.013, OR = 1.44) after the first injection.Conclusions: About half of patients with type 1 ROP may require retreatment 2 months after the first ranibizumab injection. Delayed loss of the plus sign increases the risk of retreatment; careful fundus examination is recommended after the first injection.