Vaso proliferation typically occurs after normalization of oxygen tension. The severity of the vasoobliteration is directly proportional to the duration and concentration of excess oxygen and to the degree of immaturity of the retinal vascular system. The toxic effects of oxygen can be prevented by intermittent breathing. Completely vascularized retinas of animals and humans are imnmune to the toxic effects of oxgen. The disorder makes its appearance between 10 days and 1 month after birth.
Bilateral involvement is nearly invariable.
Myopia is present in a great majority to ROPs as a long term sequlae. One gram of hemoglobin can only combine with 1.34 ml of oxygen. Therefore, red blood cells can only deliver a limited level of oxygen to tissue cells. Injuries, infections and diseases can drop this vital tissue oxygen level down to very low levels. Ischemia, drops the pO2 gravely low, destroys tissue, and slows healing.