Oxygen distribution in the mouse retina.

PURPOSE: To make the first measurements of intraretinal oxygen distribution in the mouse, an animal model of increasing importance in ophthalmic research.
METHODS: Oxygen-sensitive microelectrodes were used to measure oxygen tension as a function of depth through the retina and choroid in anesthetized mice (n = 8). All measurements were performed under light-adapted conditions, with the animals spontaneously inspiring room air. The oxygen distribution in the avascular portion of the outer retina was analyzed by an established three-layer mathematical model that determines outer retinal oxygen consumption.
RESULTS: The intraretinal oxygen distribution in the inner retina in individual profiles was often characterized by sharp peaks associated with elements of the retinal microvasculature, but, in the outer retina, the oxygen distribution was much more predictable and reflected the high oxygen uptake of the photoreceptors. Average choroidal oxygen tension was 42.0 +/- 1.2 mm Hg (mean +/- SE), and P(O2) at the surface of the retina was 21.7 +/- 0.8 mm Hg. The average minimum oxygen tension in the outer retina was 4.2 +/- 0.5 mm Hg. Average outer retinal oxygen consumption in the mouse was 193.3 +/- 10.6 nL O2/min per square centimeter, which is similar to that previously reported in the outer retina in vascularized areas of retina in the rat and monkey using similar techniques.
CONCLUSIONS: The intraretinal oxygen distribution in the mouse is qualitatively and quantitatively similar to that in other species with vascularized retinas. The rate of oxygen consumption in the outer retina is also similar. These baseline data can now be used in studies employing mouse models of retinal disease.