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| Sponsor: | Medical University of Vienna |
|---|---|
| Information provided by: | Medical University of Vienna |
| ClinicalTrials.gov Identifier: | NCT00275756 |
Purpose
Background
Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. The existence of an effective autoregulation in the optic nerve circulation has been shown in animals and humans. The exact mechanism behind this autoregulation is still unknown. The motive for the investigation of optic nerve head (ONH) blood flow autoregulation is to enhance the understanding of pathologic eye conditions associated with ocular vascular disorders. To clarify the regulatory mechanisms of ONH microcirculation is of critical importance to understand the pathophysiology of glaucoma, because there is evidence that glaucoma is associated with optic nerve head ischemia. Several studies indicate that a disturbed autoregulation might contribute to glaucomatous optic neuropathy. Currently, five classes of intraocular pressure (IOP) reducing drugs are available for topical therapy in patients with glaucoma or elevated intraocular pressure. These drugs have also vasoactive properties, which may influence both the resting ocular circulation and the autoregulatory mechanisms of blood flow during changes in ocular perfusion pressure.
Study objective
To investigate the influence of common topical glaucoma therapy on ONH blood flow regulation during changes in IOP and systemic arterial blood pressure.
| Condition | Intervention |
|---|---|
|
Glaucoma Ocular Physiology Regional Blood Flow |
Drug: Timolol (drug) Drug: dorzolamide (drug) Drug: brimonidine (drug) Device: Laser Doppler flowmetry Device: Goldmann applanation tonometer Procedure: Suction cup method |
| Study Type: | Interventional |
| Study Design: | Allocation: Randomized Endpoint Classification: Safety/Efficacy Study Intervention Model: Parallel Assignment Masking: Double Blind (Subject, Investigator) Primary Purpose: Basic Science |
| Official Title: | Effects of Common Topical Glaucoma Therapy on Optic Nerve Head Blood Flow Autoregulation During Increased Arterial Blood Pressure and Artificially Elevated Intraocular Pressure in Healthy Humans |
| Estimated Enrollment: | 54 |
| Study Start Date: | September 2008 |
| Estimated Study Completion Date: | December 2009 |
| Estimated Primary Completion Date: | December 2009 (Final data collection date for primary outcome measure) |
| Arms | Assigned Interventions |
|---|---|
| Experimental: 1 |
Drug: Timolol (drug)
Timolol (0.5%, non-selective beta-blocker, Timoptic®, Merck Sharp & Dohme, Haarlem, Netherlands), dose 1 drop in one eye twice daily for two weeks
Device: Laser Doppler flowmetry
blood flow measurements at the temporal neuroretinal rim of the optic nerve head, in total 4x 9 minutes on 2 study days
Device: Goldmann applanation tonometer
intraocular pressure measurements, in total 2x 5 measurements on two study days
Procedure: Suction cup method
The IOP will be raised by an 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus; 4x 8 minutes on 2 study days
|
| Experimental: 2 |
Drug: dorzolamide (drug)
Dorzolamide (2%, carbonic anhydrase inhibitor, Trusopt®, Laboratoires Merck Sharp & Dohme - Chibret, France), dose: 1 drop in one eye twice daily for two weeks
Device: Laser Doppler flowmetry
blood flow measurements at the temporal neuroretinal rim of the optic nerve head, in total 4x 9 minutes on 2 study days
Device: Goldmann applanation tonometer
intraocular pressure measurements, in total 2x 5 measurements on two study days
Procedure: Suction cup method
The IOP will be raised by an 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus; 4x 8 minutes on 2 study days
|
| Experimental: 3 |
Drug: brimonidine (drug)
Brimonidine (0.2%. alpha-2 adrenergic agonist, Alphagan®, Allergan Pharmaceuticals, Westport, Ireland), dose: 1 drop in one eye twice daily for two weeks
Device: Laser Doppler flowmetry
blood flow measurements at the temporal neuroretinal rim of the optic nerve head, in total 4x 9 minutes on 2 study days
Device: Goldmann applanation tonometer
intraocular pressure measurements, in total 2x 5 measurements on two study days
Procedure: Suction cup method
The IOP will be raised by an 11 mm diameter, standardized suction cup placed on the temporal sclera with the anterior edge at least 1 mm from the limbus; 4x 8 minutes on 2 study days
|
Eligibility| Ages Eligible for Study: | 19 Years to 35 Years |
| Genders Eligible for Study: | Both |
| Accepts Healthy Volunteers: | Yes |
Inclusion Criteria:
Exclusion Criteria:
Contacts and Locations| Contact: Gerhard Garhofer, MD | + 43 1 40400 2981 | gerhard.garhoefer@meduniwien.ac.at |
| Austria | |
| Department of Clinical Pharmacology | Not yet recruiting |
| Vienna, Austria, A-1090 | |
| Principal Investigator: | Gabriele Fuchsjaeger-Mayrl, MD | Department of Clinical Pharmacology |
More Information
| Responsible Party: | Gabriele Fuchsjaeger-Mayrl, MD, Department of Clinical Pharmacology, Medical University of Vienna |
| ClinicalTrials.gov Identifier: | NCT00275756 History of Changes |
| Other Study ID Numbers: | OPHT-040106 |
| Study First Received: | January 11, 2006 |
| Last Updated: | July 8, 2008 |
| Health Authority: | Austria: Agency for Health and Food Safety |
|
Glaucoma Brimonidine Timoptic Dorzolamide ocular blood flow |
|
Glaucoma Ocular Hypertension Eye Diseases Timolol Brimonidine Dorzolamide Adrenergic beta-Antagonists Adrenergic Antagonists Adrenergic Agents Neurotransmitter Agents Molecular Mechanisms of Pharmacological Action |
Pharmacologic Actions Physiological Effects of Drugs Anti-Arrhythmia Agents Cardiovascular Agents Therapeutic Uses Antihypertensive Agents Adrenergic alpha-2 Receptor Agonists Adrenergic alpha-Agonists Adrenergic Agonists Carbonic Anhydrase Inhibitors Enzyme Inhibitors |
