GSTM1 and retinopathy of prematurity: In this study, we have analyzed the value of some biochemical and hematological parameters of the blood of premature infants including the number of white blood cells (WBC), platelets (Plt), hemoglobin (Hb), reticulocytes, total and direct bilirubin (Bili T, Bili D), blood urea nitrogen (BUN), creatinine (Cr), sodium (Na), potassium (K), calcium, blood sugar, C-reactive protein (CRP) and pH to investigate the differences between different ROP and its remission/ progression statuses regarding stages and zones.