Purpose: The aim of the study was to assess the outcomes of severe retinopathy of prematurity (ROP) in zone I or posterior zone II treated with intravitreal ranibizumab (IVR) as monotherapy or combined treatment with laser photocoagulation. Methods: This is a retrospective study analyzing clinical records of the included patients. Patients were divided into two groups: group 1 included patients who received only IVR treatment; and group 2 was subdivided into group 2A – including patients with IVR as initial treatment and complementary laser photocoagulation if retinal neovascularization or plus disease did not regress, and group 2B – including patients with initial laser photocoagulation and IVR as rescue therapy. Favorable outcomes were regression of the retinal neovascularization and plus disease, meaning control of the disease. Unfavorable outcomes were progression to stages 4 and 5 of ROP. Results: Fifty-seven eyes were included in the study. Mean birth weight and gestational age were 1,281±254 g and 29.5±2.1 weeks, respectively. Group 1 comprised of 16 eyes, with favorable outcomes in 14 eyes (87.5%). Group 2 comprised of 41 eyes, with favorable outcomes in 29 eyes (70.7%), in a mean follow-up period of 12.8 months. Conclusion: IVR was effective to treat severe cases of ROP as a primary or a combined treatment. Forty-three of the 57 treated eyes (75.4%) achieved regression of ROP and favorable outcomes
