An interventional study of NG-monomethyl-L-arginine (L-NMMA) and Phenylephrine in Healthy, sponsored by Medical University of Vienna. Terminated at 1 site in Austria. Open to participants aged 18 Years to 35 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2014-11-14.
Sponsored by Medical University of Vienna · Not applicable, Interventional, and Basic science
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. 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 focused mainly on choroidal blood flow. For the optic nerve head only few data are available, although it seems likely that it underlies similar autoregulatory mechanisms.
A previous study investigating choroidal blood flow has shown that nitric oxide (NO) plays a key role in choroidal autoregulation. The present study is designed to test the hypothesis that NO plays a role in optic nerve head autoregulation during increased intraocular pressure (IOP). Therefore, IOP will be experimentally increased using a suction cup device in the absence of presence of either a nitric oxide synthase inhibitor (L-NMMA), an α-receptor agonist (phenylephrine) or placebo. Optic nerve head blood flow will be continuously measured during the procedure.
Medical University of Vienna is the lead sponsor of 1,076 studies on the registry; 177 are open to participants now.
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Drug: NG-monomethyl-L-arginine (L-NMMA) · Drug: Phenylephrine · Drug: Physiological saline solution (as placebo) · Device: Laser Doppler Flowmetry · Device: Goldmann applanation tonometer · Device: Suction cup
Drug: NG-monomethyl-L-arginine (L-NMMA) · Drug: Phenylephrine · Drug: Physiological saline solution (as placebo) · Device: Laser Doppler Flowmetry · Device: Goldmann applanation tonometer · Device: Suction cup
Drug: NG-monomethyl-L-arginine (L-NMMA) · Drug: Phenylephrine · Drug: Physiological saline solution (as placebo) · Device: Laser Doppler Flowmetry · Device: Goldmann applanation tonometer · Device: Suction cup
bolus 6mg/kg over 5 minutes followed by a continuous infusion of 60µg/kg/min over 15 minutes
1µg/kg/min, infusion period 20 minutes
infusion period 20 minutes
Measurements will be performed at the neuroretinal rim to assess ONH blood flow.
intraocular pressure measurements
Experimental stepwise increase of intraocular pressure while measurement of optic nerve head blood flow.
optic nerve head pressure-flow relationship
Time frame: 1 year
This study is terminated, as verified in Nov 2014. You cannot join it, but the record below documents what was studied.
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Medical University of Vienna