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Regulation of Optic Nerve Head Blood Flow During Combined Changes in Intraocular Pressure and Arterial Blood Pressure

NCT ID: NCT00914992

Last Updated: 2014-12-08

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

WITHDRAWN

Clinical Phase

NA

Study Classification

INTERVENTIONAL

Study Start Date

2009-07-31

Study Completion Date

2010-12-31

Brief Summary

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Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. The existence of an effective autoregulation in the optic nerve head (ONH) circulation has been shown in animals and humans. Moderate elevation of intraocular pressure (IOP) caused only slight effect on ONH blood flow in monkeys, cats and rabbits. In humans, during an artificial IOP rise using a suction cup method the ONH blood flow maintains almost constant until IOP reaches 40-55 mmHg. During isometric exercise the upper limit of autoregulation appears to be approximately 40% above the baseline ocular perfusion pressure. The mechanism behind ONH blood flow autoregulation is still unknown. The present experiments are designed to improve the investigators' knowledge of the physiology of regulatory mechanisms in ONH circulation, which may be helpful for a better understanding of blood flow abnormalities in glaucoma. This is of importance, because there is increasing evidence that vascular dysregulation plays a role in the development of glaucomatous damage.

Detailed Description

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Conditions

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Healthy

Keywords

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optic disk regional blood flow autoregulation

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

CROSSOVER

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Interventions

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Suction cup application

The IOP will be raised by an 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus.

Intervention Type PROCEDURE

Squatting

Squatting

Intervention Type OTHER

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-310505

Identifier Type: -

Identifier Source: org_study_id