NCT00810927

Role of Nitrogen Oxide (NO) in the Control of Choroidal Blood Flow During a Decrease in Ocular Perfusion Pressure

Role of NO in the Control of Choroidal Blood Flow During a Decrease in Ocular Perfusion Pressure

• Status: Completed
• Phase: Phase 2
• Study type: Interventional
• Enrollment: 22 (actual)
• Sponsor: Medical University of Vienna · Academic / Other
• Sex: Male
• Age: 19 Years – 35 Years
• Healthy volunteers: Accepted

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. In the present study autoregulation of the choroid will be investigated 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 or presence of a NO synthase inhibitor. As a control substance the alpha-receptor agonist phenylephrine will be used.

Conditions

• Physiology, Ocular
• Microcirculation
• Regional Blood Flow
• Autoregulation

Interventions

Type	Name	Description
PROCEDURE	Suction cup application	he IOP will be raised by a 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus.
PROCEDURE	Laser Doppler flowmetry	Measurement of choroidal blood flow
PROCEDURE	Measurement of intraocular pressure

Timeline

• Start date: 2003-09-01
• Primary completion: 2004-02-01
• Completion: 2005-08-01
• First posted: 2008-12-18
• Last updated: 2008-12-18

Locations

1 site across 1 country: Austria