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

NCT ID: NCT00812526

Last Updated: 2008-12-22

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

NA

Total Enrollment

18 participants

Study Classification

INTERVENTIONAL

Study Start Date

2002-09-30

Study Completion Date

2004-09-30

Brief Summary

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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.

Detailed Description

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Conditions

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Autoregulation

Keywords

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Choroid Regional blood flow Autoregulation Laser Doppler flowmetry

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

SINGLE_GROUP

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Interventions

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Suction cup application

Intervention Type PROCEDURE

Squatting

Intervention Type PROCEDURE

Eligibility Criteria

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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
Minimum Eligible Age

19 Years

Maximum Eligible Age

35 Years

Eligible Sex

MALE

Accepts Healthy Volunteers

Yes

Sponsors

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Medical University of Vienna

OTHER

Sponsor Role lead

Responsible Party

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Department of Clinical Pharmacology, Medical University of Vienna

Principal Investigators

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Elzbieta Polska, MD

Role: STUDY_DIRECTOR

Department of Clinical Pharmacology, Medical University of Vienna

Locations

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Department of Clinical Pharmacology, Medical University of Vienna

Vienna, , Austria

Site Status

Countries

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Austria

Other Identifiers

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OPHT-190702

Identifier Type: -

Identifier Source: org_study_id