Autoregulation of Ocular Blood Flow

The pressure-flow relationship of the total ocular vascular bed in the enucleated eye and of the anterior uveal circulation in the living in situ eye were determined. In the enucleated eye, perfusion of the ophthalmic artery with lactated Ringer's solution, fresh plasma, or oxygenated whole blood resulted in a linear pressureflow relationship indicative of a passive vascular bed. In the living in situ eye, in which a fistula was created between one common carotid artery and the temporal long posterior ciliary artery, autoregulation of blood flow was detected in 40% of the eyes. Measurements of anterior uveal blood flow without creating a carotid-ciliary artery fistula demonstrated a high degree of autoregulation of blood flow at ciliary artery blood pressures above 60 to 90 mm Hg in all eyes. The results indicate that the myogenic hypothesis represents the major mechanism of autoregulation in the anterior uveal circulation.