HISTORY AND INTRODUCTION
Retinopathy of prematurity (ROP) is a disease affecting the retina of premature infants (Figs 1.1A to C). Its key pathologic change, retinal neovascularization, has several features in common with the other proliferative retinopathies such as diabetic and sickle cell retinopathy. Each of these proliferative retinal vascular disorders appears to be associated with local ischemia and the subsequent development of neovascularization.
- First identified by Terry1 in 1942, Terry's original reports designated the condition retrolental fibroplasia based on his impression that the primary change involved a proliferation of the embryonic hyaloid system which incorporated the retina. He studied the unilateral pathological specimens (most likely to be PHPV) and provided details which he thought may be identical with bilateral cases of retrolental fibroplasia.
- The term ROP was coined by Heath in 1951. He was much more precise in his descriptions and his histopathological studies offered rare insight into the disease processes as it was then understood.
- In 1951, Campbell suggested that toxic effects of uncontrolled oxygen to new-borns were responsible for the epidemic.2 She suggested avoiding use of oxygen and use only if the child is cyanosed.
- The incrimination of oxygen as the principal cause of ROP was made in the 1950s.3,4 Subsequent studies showed high levels of oxygen obliterated blood vessels of the neonatal retina. Controlled use of oxygen although lowered the proportion of blindness (In USA alone from 50% in 1950 to 4% in 1965) but it increased the neonatal deaths due to atelectasis and respiratory distress secondary to hyaline membrane disease.5,6
- In 1981, Phelps8 estimated the incidence of ROP associated with an increase in survival rates of infants with birth weights less than 1,000 gm.
- In 1983, International Classification of Retinopathy of Prematurity was devised under the leadership of John Flynn.10
- In 1970s the Japanese physicians treated the ridge and the adjacent avascular retina.11 Hindle and Leyton, in Canada, treated the ridge, and the retina anterior and posterior to it. McPherson, Hittner, and Kretzner advocated cryotherapy of the ridge and adjacent posterior avascular zone to destroy the spindle cells, the presumed source of angiogenic factor.12
- In Asian countries like India, due to lopsided health care, i.e. due to extremes of health care, state of the art tertiary health care neonatal center and almost defunct neonatal primary health care centers, both first and second epidemic exist, and may be called as the third or mixed epidemic.