Vascular Perfusion Pressure Gradients in the Eye

Abstract

The intraocular pressures required to terminate blood flow in the retina, choroid, and anterior uvea were compared. The retinal and choroidal circulations were studied by ophthalmodynamometry while the choroidal and anterior uveal circulations were compared by direct cannulation experiments. The results indicated that as intraocular pressure is gradually elevated toward ophthalmic artery pressure, blood flow ceases in a sequential pattern in the anterior uveal, choroidal, and retinal circulations. Systolic and diastolic blood pressures were 14 and 13 mm. Hg lower, respectively, in the choroid than in the retina. Circulation ceased in the anterior uvea at levels of intraocidar pressure 5 to 20 mm. Hg lower than that required to terminate blood flow in the choroid. The relationship of these results to vascular perfusion pressure in various segments of the eye is discussed.