"ROP, which is a major complication of preterm births, contributes to the leading cause of childhood blindness. The prevalence of ROP is associated with low birth weight, low gestational age, supplemental oxygen therapy, low insulin-like growth factor (IGF-1) level, and genetic mutation. Due to the increased survival of extreme low birth
weight infants (â¤ 1000 g) with improved neonatal care, the risk for ROP has also been increased. ROP is a biphasic disease with a first phase of vessel growth cessation and a second phase of vessel proliferation. In human, the development of retinal vasculature starts from the 16th week of gestation and finishes just before term, i.e. the 40th week of gestation, in a central-to-peripheral manner. The relative hyperoxia of the extra-uterine environment with or without supplemental oxygen during hospitalization, together with a efficiency of autoregulation, result in an increase of free oxygen radical and a decrease of vascular endothelial growth factor (VEGF) in the premature retina and subsequently the regression of developed retinal vessels. Incomplete development of the retinal vasculature therefore limits retinal blood circulation, leading to a peripheral avascular a vascular zone in the retina of preterm infants. However, as the infants grow, the non-vascul rized retina becomes increasingly metabolically active and more oxygen is in turn required, resulting in tissue hypoxia which then stimulates vessel proliferation. In severe cases, this proliferation triggers uncontrolled pathological regrowth of the overstated, disorganized, fragile, and leaky vessels from the retina into the vitreous, proceeding to hemorrhage and cloudy vision. Fibrous scar is eventually formed and retraction of which can result in detachment of retina from the retina pigment epithelium and even blindness if remains untreated. In general, the extent of human ROP is ategorized into five stages based on the vasculature.
(Angela Ka Wai Lai, Zhong Jie Fu and Amy CY Lo- Stem Cell Therapy for Retinopathy of Prematurity)."
Last date updated on June, 2014