The vascularization process after intravitreal ranibizumab injections for aggressive posterior retinopathy of prematurity.

Purpose: To evaluate the retinal vascularization process after intravitreal ranibizumab was administered to infants with aggressive posterior retinopathy of prematurity (AP-ROP). Methods: Twenty-six eyes of 13 infants with AP-ROP who received 0.25 mg intravitreal ranibizumab were retrospectively investigated. The patients were evaluated at weekly follow-up visits, and the findings were analyzed after retinal vascularization was complete. Results: The results showed regression in the AP-ROP of all the patients within the first 48-72 h. Average time for complete vascularization of the nasal quadrant (zone II) was postmenstrual week 45 (range 41-56), and vascularization of the temporal quadrant (zone III) was completed in the postmenstrual week 56 (range 50-65). Reactivation was observed in seven patients, on average at postmenstrual week 42; two of these patients underwent additional treatment. Two patients presented with avascular areas in the peripheral retina despite being 1 year old. Conclusion: These results showed that retinal vascularization following intravitreal ranibizumab was completed after a delay in patients with AP-ROP. Further studies are necessary to evaluate when and how vascularization occurs after intravitreal anti-vascular endothelial growth factor treatments.