Optic Nerve Head Autoregulation During Changes in Arterial Blood Pressure
Constant despite changes in perfusion pressure. It is observed in many vascular beds of the human body to prevent that variations in perfusion pressure are directly transmitted into changes in blood flow. This is necessary to prevent ischemia and/or hypoxia during decreased blood flow and bleeding or increased capillary pressure during increased blood flow.
In the eye, several studies have reported that retinal blood flow is autoregulated over a wide range of ocular perfusion pressures. Unfortunately only few data are available for the optic nerve head. To gain data about autoregulation is of special importance given that several important ocular diseases such as glaucoma and age-related macular degeneration are associated with impaired autoregulation. In humans most data were collected using laser Doppler flowmetry.
The present study aims to investigate the phenomenon of transient reduction in blood flow and to gain insight in the regulatory mechanisms of optic nerve head blood flow during isometric exercise.
|Study Design:||Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Basic Science
- Optic nerve head blood flow [ Time Frame: 12 minutes ] [ Designated as safety issue: No ]
- Systolic/diastolic blood pressure [ Time Frame: 14 minutes ] [ Designated as safety issue: Yes ]
- Intraocular pressure [ Time Frame: at baseline and minute 13 ] [ Designated as safety issue: No ]
- Pulse rate [ Time Frame: 14 minutes ] [ Designated as safety issue: Yes ]
|Study Start Date:||February 2012|
|Study Completion Date:||August 2012|
|Primary Completion Date:||April 2012 (Final data collection date for primary outcome measure)|
|Experimental: Healthy subjects||
Other: Isometric exercise
use of a handgrip for 3x2 minutes
|Department of Clinical Pharmacology|
|Vienna, Austria, 1090|
|Principal Investigator:||Gerhard Garhöfer, MD||Department of Clinical Pharmacology, Medical University of Vienna|