EPO and retinopathy of prematurity: High levels of VEGF-Receptor 1, IL-8, matrix metalloproteinase 9 (MMP-9), erythropoietin (EPO), tumor necrosis factor (TNF)-α and basic fibroblast growth factor (bFGF) are related to a risk factor for prethreshold ROP in the first three postnatal weeks (48).