To compare type I retinopathy of prematurity (ROP) with aggressive posterior retinopathy of prematurity (AP- ROP) regarding risk factors, complications and treatment outcomes.

A prospective cohort approach was applied on premature newborns diagnosed as Type I ROP and AP-ROP. An intravitreal injection of bevacizumab (Avastin®) was given to each patient. Demographic features such as gestational age, birth weight, age at the initial injection, involved eye, treatment response, relapses and need to extra interventions were compared.

Seventy-seven patients underwent an initial intravitreal injection of Bevacizumab (IVB), 108 eyes were type I ROP and 30 eyes were A-P ROP. There was no significant difference in birth weight and gestational age (GA) between two groups. ROP relapsed in 8 eyes of 4 patients with A-P ROP (26.6 %), of which 6 eyes of 3 patients received re-injection of bevacizumab, and 2 eyes of one patient underwent a laser treatment. Recurrence occurred in 2 eyes of one patient with Type I ROP (1.8 %), which were treated by laser.

Bilateral eye involvement, relapse and retreatment (IVB, laser and surgical intervention) are more frequent in A-P ROP than type I ROP even when treated with intravitreal Bevacizumab injection.