Retinal Vascular Changes in a Model of Retinopathy of Prematurity Using Oxygen Fluctuations and an Early, Short Duration of Hypercarbia

Abstract

Abstract: : Purpose: To determine the effects of short versus long duration hypercarbia and fluctuating oxygen on the developing rat retinal vasculature. Methods: Newborn rats were exposed to oxygen and carbon dioxide in one of three groups: (1) Variable oxygen exposure (VO₂) (2)VO₂ with 2 days 5% carbon dioxide (2CO₂ +VO₂) (3) VO₂ with 14 days 5% carbon dioxide (14CO₂ + VO₂). Following sacrifice at day 14, the eyes were enucleated, fixed in 2% PFA and retinal wholemounts prepared. Blood vessels were visualised by staining the endothelial cells using G.simplicifolia (Bandeiraea) isolectin B4 and the median number of branches and the peripheral avascular area were assessed by confocal microscopy. Comparisons of groups was made by Mann Whitney U. Results: * p<0.05 compared to control. ** p<0.001 compared to control. # p<0.001 compared to control and variable oxygen. Conclusion: All experimental protocols induced features of retinopathy in rat pups. However, pups exposed to carbon dioxide had increased capillary branching and a greater peripheral avascular area when compared with controls. A prolonged exposure to carbon dioxide produced no greater retinopathy than a short, early exposure.  

Keywords: 572 retinopathy of prematurity • 316 animal model