Regulation of Choroidal Blood Flow During Combined Changes in Intraocular Pressure and Arterial Blood Pressure

December 19, 2008 updated by: Medical University of Vienna
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 choroid. Choroidal autoregulation was first shown in a rabbit model where intraocular pressure (IOP) and arterial blood pressure could be varied independently. In these experiments regulation of choroidal blood flow was not only dependent on ocular perfusion pressure, but was also dependent on the value of IOP. This indicates that a myogenic mechanism contributes to choroidal autoregulation, because the regulatory capacity is dependent on the transmural pressure. In the model of myogenic autoregulation arterioles change their vascular tone depending on the pressure inside the vessel and outside the vessel. The present experiments are designed to test whether a myogenic mechanism may also be involved in choroidal autoregulation in humans. For this purpose the investigators perform experiments during which the IOP and the arterial blood pressure is increased. According to the myogenic theory of autoregulation one would expect stronger vasoconstriction at lower IOPs for the same increase in ocular perfusion pressure.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

18

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Austria
      • Vienna, Austria, 1090
        • Department of Clinical Pharmacology, Medical University of Vienna

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

19 years to 35 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Male

Description

Inclusion Criteria:

  • Men aged between 19 and 35 years, nonsmokers
  • Body mass index between 15th and 85th percentile
  • Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
  • Normal ophthalmic findings, ametropia < 1 Dpt.

Exclusion Criteria:

  • Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study
  • Treatment in the previous 3 weeks with any drug
  • Symptoms of a clinically relevant illness in the 3 weeks before the first study day
  • Blood donation during the previous 3 weeks
  • Presence of intraocular pathology: ocular hypertension, glaucoma, retinal vasculopathy or other retinal diseases

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Non-Randomized
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Relationship between ocular perfusion pressure and choroidal blood flow
Time Frame: 4 study days
4 study days

Secondary Outcome Measures

Outcome Measure
Time Frame
Choroidal blood flow
Time Frame: 4 study days
4 study days
Mean arterial pressure
Time Frame: 4 study days
4 study days
Intraocular pressure
Time Frame: 4 study days
4 study days
Systolic/diastolic blood pressure
Time Frame: 4 study days
4 study days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Medical University of Vienna

Investigators

  • Study Director: Elzbieta Polska, MD, Department of Clinical Pharmacology, Medical University of Vienna

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

September 1, 2002

Primary Completion (Actual)

September 1, 2004

Study Completion (Actual)

September 1, 2004

Study Registration Dates

First Submitted

December 18, 2008

First Submitted That Met QC Criteria

December 19, 2008

First Posted (Estimate)

December 22, 2008

Study Record Updates

Last Update Posted (Estimate)

December 22, 2008

Last Update Submitted That Met QC Criteria

December 19, 2008

Last Verified

December 1, 2008

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • OPHT-190702

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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