HYPOXIA PRECEDES THE DEVELOPMENT OF EXPERIMENTAL PRERETINAL NEOVASCULARIZATION

Background: Although the mechanism of preretinal neovascular growth in the cell-injected rabbit eye model is not known, it has been proposed that the initial vasodilation and eventual development of neovascular ization may be attributable to inflammatory mediators. However, an alt ernative explanation involving hypoxia has not been considered. The pu rpose of this study was to measure preretinal oxygen tension prior to the development of preretinal neovascularization in the cell-injected rabbit eye. Methods: In the rabbit, intravitreous injections of 250 00 0 homologous dermal fibroblasts were performed on one eye; the fellow (control) eye was injected with vehicle. Preretinal oxygen tension ove r the myelin wing was measured using F-19-NMR spectroscopy of a 30-mu l droplet of perfluorocarbon previously injected into the preretinal v itreous. Results: Compared to control eyes, fibroblast-injected eyes s howed a 1.7-fold decrease in preretinal oxygen tension from the first time studied (1 day after cell injection) through the development of v isible neovascularization. Hypoxia occurred without coexisting ophthal moscopic evidence of vascular occlusion or, on days 1 and 3 after cell injection, retinal detachment. Conclusion: This result demonstrates f or the first time that preretinal hypoxia precedes the development of preretinal neovascularization in the fibroblast-injected rabbit eye.