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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
History of Changes
  Purpose

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 Intervention
Healthy
 Procedure: Suction cup application
Procedure: Squatting

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: 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.

Further study details as provided by Medical University of Vienna:

Primary Outcome Measures:
  • Ocular perfusion pressure - ONH blood flow relationship [ Time Frame: 9 months ] [ Designated as safety issue: No ]

Estimated Enrollment: 36
Study Start Date: September 2009
Estimated Study Completion Date: October 2010
Estimated Primary Completion Date: June 2010 (Final data collection date for primary outcome measure)
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
    Squatting
  Eligibility

Ages Eligible for Study:   19 Years to 35 Years
Genders Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes
Criteria

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
  Contacts and Locations
Please refer to this study by its ClinicalTrials.gov identifier: NCT00915226

Contacts
Contact: Gerhard Garhöfer, MD +43140400 ext 2981 gerhard.garhoefer@meduniwien.ac.at

Locations
Austria
Department of Clinical Pharmacology, Medical University of Vienna Not yet recruiting
Vienna, Austria, 1090
Sponsors and Collaborators
Medical University of Vienna
Investigators
Study Director: Elzbieta Polska, MD Department of Clinical Pharmacology, Medical University of Vienna
  More Information

No publications provided

Responsible Party: Elzbieta Polska, MD, Department of Clinical Pharmacology, Medical University of Vienna
ClinicalTrials.gov Identifier: NCT00915226     History of Changes
Other Study ID Numbers: OPHT-310505-2
Study First Received: June 3, 2009
Last Updated: June 4, 2009
Health Authority: Austria: Agency for Health and Food Safety

Keywords provided by Medical University of Vienna:
Optic disk
Regional blood flow
Autoregulation

ClinicalTrials.gov processed this record on May 21, 2013