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

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT00912665
First Posted: June 3, 2009
Last Update Posted: August 10, 2012
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.
Information provided by (Responsible Party):
Gerhard Garhofer, Medical University of Vienna
  Purpose

Autoregulation is defined as the ability of a vascular bed to adapt its vascular resistance to changes in perfusion pressure. In the eye, several studies have reported that retinal blood flow is autoregulated over a wide range of ocular perfusion pressures. In the optic nerve head only few data are available. Large scale studies have shown that reduced ocular perfusion pressure is an important risk factor for the prevalence, the incidence and the progression of primary open angle glaucoma.

Former studies that investigated ocular blood flow autoregulation only measured choroidal blood flow. For the optic nerve head only few data are available, although it seems likely that it underlies similar autoregulatory mechanisms.

The primary goal of the present study is to gain more insight into these phenomena in humans.

The present study aims to investigate the pressure/flow relationship as a measure for optic nerve head autoregulation during combined changes of intraocular pressure and arterial pressure. Intraocular pressure will be increased by the use of a suction cup technique, mean arterial pressure will be increased by squatting. During the whole procedure, optic nerve head blood flow will be measured continuously.


Condition Intervention
Healthy Device: Laser Doppler Flowmetry Device: Goldmann applanation tonometer Other: squatting Device: Suction cup

Study Type: Interventional
Study Design: Intervention Model: Single Group 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

Resource links provided by NLM:


Further study details as provided by Gerhard Garhofer, Medical University of Vienna:

Primary Outcome Measures:
  • Optic nerve head pressure-flow relationship [ Time Frame: in total 3x on 2 study days ]

Enrollment: 40
Study Start Date: July 2009
Study Completion Date: December 2010
Primary Completion Date: December 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Healthy Volunteer Device: Laser Doppler Flowmetry
blood flow measurements at the temporal neuroretinal rim to assess optic nerve head blood flow
Device: Goldmann applanation tonometer
intraocular pressure measurements
Other: squatting
Subjects will perform squatting for 6 minutes while either blood flow or intraocular pressure measurements
Device: Suction cup
Experimental stepwise increase of intraocular pressure while either optic nerve head blood flow or intraocular pressure measurements

  Eligibility

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.


Ages Eligible for Study:   18 Years to 35 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Men and women aged between 18 and 35 years, nonsmokers
  • Men and women will be included in equal parts
  • Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
  • Normal findings in the laboratory testings unless the investigator considers an abnormality to be clinically irrelevant
  • Normal ophthalmic findings, ametropia less than 1 diopter

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 (except oral contraceptives)
  • Symptoms of a clinically relevant illness in the 3 weeks before the first study day
  • Blood donation during the previous 3 weeks
  Contacts and Locations
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 ClinicalTrials.gov identifier (NCT number): NCT00912665


Locations
Austria
Department of Clinical Pharmacology, Medical University of Vienna
Vienna, Austria, 1090
Sponsors and Collaborators
Medical University of Vienna
  More Information

Responsible Party: Gerhard Garhofer, Ass.Prof.Priv.Doz.Dr., Medical University of Vienna
ClinicalTrials.gov Identifier: NCT00912665     History of Changes
Other Study ID Numbers: OPHT-150808
First Submitted: June 1, 2009
First Posted: June 3, 2009
Last Update Posted: August 10, 2012
Last Verified: August 2012

Keywords provided by Gerhard Garhofer, Medical University of Vienna:
Optic Nerve Head Blood Flow
Intraocular Pressure
Regional Blood Flow
Ocular Physiology
Optic Disk