Role of Nitric Oxide in Optic Nerve Head Blood Flow Regulation During Experimental Increase of Intraocular Pressure in Healthy Humans
NCT ID: NCT00914394
Last Updated: 2014-11-14
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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TERMINATED
NA
12 participants
INTERVENTIONAL
2010-10-31
Brief Summary
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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.
Detailed Description
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Conditions
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Study Design
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RANDOMIZED
CROSSOVER
BASIC_SCIENCE
TRIPLE
Study Groups
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NG-monomethyl-L-arginine (L-NMMA)
NG-monomethyl-L-arginine (L-NMMA)
bolus 6mg/kg over 5 minutes followed by a continuous infusion of 60µg/kg/min over 15 minutes
Phenylephrine
1µg/kg/min, infusion period 20 minutes
Physiological saline solution (as placebo)
infusion period 20 minutes
Laser Doppler Flowmetry
Measurements will be performed at the neuroretinal rim to assess ONH blood flow.
Goldmann applanation tonometer
intraocular pressure measurements
Suction cup
Experimental stepwise increase of intraocular pressure while measurement of optic nerve head blood flow.
Phenylephrine
NG-monomethyl-L-arginine (L-NMMA)
bolus 6mg/kg over 5 minutes followed by a continuous infusion of 60µg/kg/min over 15 minutes
Phenylephrine
1µg/kg/min, infusion period 20 minutes
Physiological saline solution (as placebo)
infusion period 20 minutes
Laser Doppler Flowmetry
Measurements will be performed at the neuroretinal rim to assess ONH blood flow.
Goldmann applanation tonometer
intraocular pressure measurements
Suction cup
Experimental stepwise increase of intraocular pressure while measurement of optic nerve head blood flow.
Physiological saline solution
NG-monomethyl-L-arginine (L-NMMA)
bolus 6mg/kg over 5 minutes followed by a continuous infusion of 60µg/kg/min over 15 minutes
Phenylephrine
1µg/kg/min, infusion period 20 minutes
Physiological saline solution (as placebo)
infusion period 20 minutes
Laser Doppler Flowmetry
Measurements will be performed at the neuroretinal rim to assess ONH blood flow.
Goldmann applanation tonometer
intraocular pressure measurements
Suction cup
Experimental stepwise increase of intraocular pressure while measurement of optic nerve head blood flow.
Interventions
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NG-monomethyl-L-arginine (L-NMMA)
bolus 6mg/kg over 5 minutes followed by a continuous infusion of 60µg/kg/min over 15 minutes
Phenylephrine
1µg/kg/min, infusion period 20 minutes
Physiological saline solution (as placebo)
infusion period 20 minutes
Laser Doppler Flowmetry
Measurements will be performed at the neuroretinal rim to assess ONH blood flow.
Goldmann applanation tonometer
intraocular pressure measurements
Suction cup
Experimental stepwise increase of intraocular pressure while measurement of optic nerve head blood flow.
Eligibility Criteria
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Inclusion Criteria
* 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
* Treatment in the previous 3 weeks with any drug (except intake of oral contraceptives)
* Symptoms of a clinically relevant illness in the 3 weeks before the first study day
* History or presence of gastrointestinal, liver or kidney disease, or other conditions known to interfere with distribution, metabolism or excretion of study drugs
* Blood donation during the previous 3 weeks
* Pregnancy
18 Years
35 Years
ALL
Yes
Sponsors
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Medical University of Vienna
OTHER
Responsible Party
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Gerhard Garhofer
Assoc Prof Priv-Doz Dr
Principal Investigators
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Gabriele Fuchsjaeger-Mayrl, MD, Univ.Doz.
Role: PRINCIPAL_INVESTIGATOR
Department of Clinical Pharmacology, Medical University of Vienna
Locations
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Department of Clinical Pharmacology, Medical University of Vienna
Vienna, Vienna, Austria
Countries
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Other Identifiers
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OPHT-310708
Identifier Type: -
Identifier Source: org_study_id