To examine the effect lf light on retinal neovascularization and vasculogenesis in a reproducible and quantifiable model of oxygen-induced proliferative retinopathy in the mouse.C57Bl/6J mice were reared in room air, 68% oxygen, or 75% oxygen and were exposed to darkness, low cyclical light (200-350 lux), or high-intensity continuous light (3000-4500 lux). The entire retinal vascular pattern was visualized in fluorescein-dextran perfused flat-mount preparations. Proliferative retinopathy was quantified by counting neovascular nuclei in 6 microns cross-sections of whole eyes.Light exposure did not exacerbate the proliferative retinopathy that was seen after 68% oxygen exposure, which induced a meager proliferative response, nor after 75% oxygen exposure, which induced an exuberant proliferative response. In room air, retinas from all three illumination groups had normal vascular patterns.In this model of oxygen-induced retinopathy, under the conditions tested, light neither exacerbated the hyperoxia-induced neovascularization nor affected normal retinal vascular development.