Retinopathy. Fetal eyes are designed to develop in the low oxygen environment of the womb. The fetal o2 is seldom over 60%, but premature delivery changes that. To survive premi's have to balance the need for more oxygen of their other tissues & this sometimes causes the blood vessels supplying the retina to overgrow & scar the eye & produce visual loss. The process is called retinopathy of prematurity or rop.