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

NCT00810927 · Status: COMPLETED · Phase: PHASE2 · Type: INTERVENTIONAL · Enrollment: 22

Last updated 2008-12-18

No results posted yet for this study

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

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

Sponsors & Collaborators

  • Medical University of Vienna

    lead OTHER

Principal Investigators

  • Gabriele Fuchsjäger-Mayrl, MD · Department of Clinical Pharmacology, Medical University of Vienna

Study Design

Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Model
CROSSOVER

Eligibility

Min Age
19 Years
Max Age
35 Years
Sex
MALE
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2003-09-30
Primary Completion
2004-02-29
Completion
2005-08-31

Countries

  • Austria

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT00810927 on ClinicalTrials.gov