Relationship between blood flow velocity in the choroid and intraocular pressure in rabbits

By using thermistors for calorimetry to monitor blood flow velocity in the choroid of the anaesthetized rabbit, it was found that an elevation of intraocular pressure reduced the choroidal blood flow. The relationship between the ratio of perfusion pressure to intraocular tension (x) and the reciprocal value of the percentage of blood flow velocity (l/y) showed a curve convex towards the pressure axis. On a log-lin scale the graph was linear. A significant linear correlation with a coefficient of 0.965 was obtained. The regression equation was found to be log l/y = 0.48x-1.98 +/- 0.29. From the present experiments it is concluded that the vascular bed of the choroid in the rabbit is a passive one with no sign of autoregulation. The observations are discussed from the point of view of blood supply and possible damage to the optic disc.