Retinopathy of Prematurity

"The normal development of this blood supply for the retina starts at 16 weeks into a pregnancy and is completed by 36 weeks.

If an infant is born prematurely, with the retinal blood vessel development incomplete, problems occur. Abnormal blood vessels may develop which can subsequently lead to bleeding and scar tissue formation. This may then stretch the retina pulling it out of position. Visual loss may result.

The lack of oxygen in areas of retina which have not developed blood vessels, results in the release of chemicals that promote the growth of new blood vessels. These blood vessels often grow in an irregular manner, for reasons that are not completely understood. The presence of large amounts of oxygen (often needed for the baby's survival) is thought to be possibly toxic to the developing blood vessels. As premature babies have underdeveloped lungs they usually require additional oxygen therapy. There are other undetermined factors also contributing."