RETROLENTAL FIBROPLASIA

disease of the retinal blood vessels in the eyes of premature infants, resulting from administration of excessive amounts of oxygen in the attempt to prevent respiratory disease. Until the role of oxygen was established in 1954, the disease was a major cause of blindness. It became extremely rare when oxygen therapy was modified and monitored more closely, although it still occurs in a few infants. The immature blood vessels of the infant retina are very sensitive to oxygen; concentrations in excess of 40 percent cause the vessels to constrict, shutting off blood flow. When the oxygen is stopped, the vessels expand and become twisted, proliferating through the retina and the vitreous body, the transparent jellylike substance filling most of the eyeball. Damage in these early stages is reversible, and the recovery rate is about 50 percent. If the disease progresses, however, the blood vessels become fibrotic, and the retina detaches from the eyeball, causing permanent, irreversible blindness.