Regulation of Optic Nerve Head Blood Flow During Combined Changes in Intraocular Pressure and Arterial Blood Pressure
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.
|Healthy||Device: Laser Doppler Flowmetry Device: Goldmann applanation tonometer Other: squatting Device: Suction cup|
|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|
- Optic nerve head pressure-flow relationship [ Time Frame: in total 3x on 2 study days ]
|Study Start Date:||July 2009|
|Study Completion Date:||December 2010|
|Primary Completion Date:||December 2010 (Final data collection date for primary outcome measure)|
|Experimental: Healthy Volunteer||
Device: Laser Doppler Flowmetry
blood flow measurements at the temporal neuroretinal rim to assess optic nerve head blood flowDevice: Goldmann applanation tonometer
intraocular pressure measurementsOther: squatting
Subjects will perform squatting for 6 minutes while either blood flow or intraocular pressure measurementsDevice: Suction cup
Experimental stepwise increase of intraocular pressure while either optic nerve head blood flow or intraocular pressure measurements
Please refer to this study by its ClinicalTrials.gov identifier: NCT00912665
|Department of Clinical Pharmacology, Medical University of Vienna|
|Vienna, Austria, 1090|