Figure 1.

Retinal vessels development occurs through vasculogenesis and angiogenesis in a well-specified period of gestation, starting before week 15 and concluding around week 31. At the bottom are displayed the cases of three neonates, all receiving two RBC units at postnatal days 9 and 14 (red arrows). According to postmenstrual age, at the beginning of week 28, patient 1 had received no transfusion, patient 2 had received one single transfusion, and patient 3 was given two transfusions. RBC, red blood cell.