[Effect of changes in ocular perfusion pressure on choroid ischemia in man]

The effect of changes in ocular perfusion pressure (PPm) on the choroidal blood flow (ChBF) in man was studied with the laser Doppler flowmetry (LDF) technique.We changed the PPm by increasing the intraocular pressure (IOP) or by increasing the blood pressure (BP) with isometric exercises.We observed that a) ChBF was not significantly different from baseline up to an IOP of 27 mm Hg and b) ChBF remained constant even if PPm increased by as much as 72%.Our results suggest that ChBF is autoregulated in response to an increase in IOP up to about 27 mm Hg. ChBF remains also constant in spite of an increase in systemic BP, probably due to a vasoconstriction induced by increased sympathetic activity.