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

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00915226
Recruitment Status : Withdrawn
First Posted : June 5, 2009
Last Update Posted : November 14, 2014
Information provided by (Responsible Party):
Gerhard Garhofer, Medical University of Vienna

Brief Summary:
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.

Condition or disease Intervention/treatment Phase
Healthy Procedure: Suction cup application Procedure: Squatting Not Applicable

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 0 participants
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Regulation of Optic Nerve Head Blood Flow During Combined Changes in Intraocular Pressure and Arterial Blood Pressure.
Study Start Date : September 2009
Actual Primary Completion Date : June 2010
Actual Study Completion Date : October 2010

Intervention Details:
  • 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

Primary Outcome Measures :
  1. Ocular perfusion pressure - ONH blood flow relationship [ Time Frame: 9 months ]

Information from the National Library of Medicine

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Ages Eligible for Study:   19 Years to 35 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00915226

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Department of Clinical Pharmacology, Medical University of Vienna
Vienna, Austria, 1090
Sponsors and Collaborators
Medical University of Vienna
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Study Director: Elzbieta Polska, MD Department of Clinical Pharmacology, Medical University of Vienna
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Responsible Party: Gerhard Garhofer, Assoc. Prof Priv.-Doz. Dr, Medical University of Vienna Identifier: NCT00915226    
Other Study ID Numbers: OPHT-310505-2
First Posted: June 5, 2009    Key Record Dates
Last Update Posted: November 14, 2014
Last Verified: November 2014
Keywords provided by Gerhard Garhofer, Medical University of Vienna:
Optic disk
Regional blood flow