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

The recruitment status of this study is unknown because the information has not been verified recently.
Verified June 2009 by Medical University of Vienna.
Recruitment status was  Not yet recruiting
Sponsor:
Information provided by:
Medical University of Vienna
ClinicalTrials.gov Identifier:
NCT00915226
First received: June 3, 2009
Last updated: June 4, 2009
Last verified: June 2009

June 3, 2009
June 4, 2009
September 2009
June 2010   (final data collection date for primary outcome measure)
Ocular perfusion pressure - ONH blood flow relationship [ Time Frame: 9 months ] [ Designated as safety issue: No ]
Same as current
Complete list of historical versions of study NCT00915226 on ClinicalTrials.gov Archive Site
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Regulation of Optic Nerve Head Blood Flow During Combined Changes in Intraocular Pressure and Arterial Blood Pressure
Regulation of Optic Nerve Head Blood Flow During Combined Changes in Intraocular Pressure and Arterial Blood Pressure.

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 an increased evidence, that vascular dysregulation plays a role in the development of glaucomatous damage.

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Interventional
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Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: Open Label
Primary Purpose: Basic Science
Healthy
  • Procedure: 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.
  • Procedure: Squatting
    Squatting
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*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Not yet recruiting
36
October 2010
June 2010   (final data collection date for primary outcome measure)

Inclusion Criteria:

  • Men aged between 19 and 35 years, nonsmokers
  • Body mass index between 15th and 85th percentile (Must et al. 1991)
  • 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
Male
19 Years to 35 Years
Yes
Contact: Gerhard Garhöfer, MD +43140400 ext 2981 gerhard.garhoefer@meduniwien.ac.at
Austria
 
NCT00915226
OPHT-310505-2
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Elzbieta Polska, MD, Department of Clinical Pharmacology, Medical University of Vienna
Medical University of Vienna
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Study Director: Elzbieta Polska, MD Department of Clinical Pharmacology, Medical University of Vienna
Medical University of Vienna
June 2009

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP