Role of Adenosine in the Control of Choroidal Blood Flow During Changes in Ocular Perfusion Pressure.
Status:
Completed
Trial end date:
2005-04-01
Target enrollment:
Participant gender:
Summary
Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in
perfusion pressure. For a long time it had been assumed that the choroid is a strictly
passive vascular bed, which shows no autoregulation. However, recently several groups have
identified some autoregulatory capacity of the human choroid. In the brain and the retina the
mechanism behind autoregulation is most likely linked to changes in transmural pressure. In
this model arterioles change their vascular tone depending on the pressure inside the vessel
and outside the vessel. In the choroid, several observations argue against a direct
involvement of arterioles. However, the mechanism behind choroidal autoregulation remains
unclear. Adenosine, an endogenous purine metabolic end product with a potent vasodilatory
effect on multiple vascular beds, leads to an increase in retinal and choroidal vessel
diameter. The present study aims to investigate whether adenosine plays a role in choroidal
autoregulation during a decrease in ocular perfusion pressure, which will be achieved by an
increase in intraocular pressure.
Pressure/flow relationships will be investigated in the absence and presence of adenosine.