This study is designed as an exploratory study to assess safety and efficacy of two different doses of the anti-VEGF agent ranibizumab (0.12 mg vs. 0.20 mg) in the treatment of infants with retinopathy of prematurity. Furthermore it shall help to improve safety in the treatment of ROP and provide explorative data on long-term effects of ranibizumab after intravitreal injection in neonates.