The EU-ROP registry is a European wide multicenter non-interventional observational registry study intended to run open-ended in as many countries as possible including infants treated for retinopathy of prematurity irrespective of the used treatment modality. The registry is strictly observational; only clinical routine data is collected, no study-specific examinations or interventions are to be performed. The aim of the EU-ROP registry is to collect information on as many patients as possible treated for ROP in Europe. Both the number of study centers as well as the number of patients to be included into the registry are not limited. The primary objective is to describe the typical clinical features of infants with severe ROP, variations in phenotype, and the clinical progression of the disease over time (natural history) in different European countries as well as to study treatment patterns, follow-up patterns, as well as long-term outcomes.