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

The recruitment status of this study is unknown because the information has not been verified recently.
Verified July 2008 by Medical University of Vienna.
Recruitment status was  Not yet recruiting
Sponsor:
Information provided by:
Medical University of Vienna
ClinicalTrials.gov Identifier:
NCT00275756
First received: January 11, 2006
Last updated: July 8, 2008
Last verified: July 2008
  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

Resource links provided by NLM:


Further study details as provided by Medical University of Vienna:

Primary Outcome Measures:
  • Ocular perfusion pressure - ONH blood flow relationship [ Time Frame: on 2 study days ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Blood pressure, heart rate [ Time Frame: on 2 study days ] [ Designated as safety issue: Yes ]

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
Criteria

Inclusion Criteria:

  • Men aged between 19 and 35 years, nonsmokers
  • Body mass index between 15th and 85th percentile
  • Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
  • Normal ophthalmic findings, ametropia < 1 Dpt.

Exclusion Criteria:

  • Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study
  • Treatment in the previous 3 weeks with any drug
  • Symptoms of a clinically relevant illness in the 3 weeks before the first study day
  • Blood donation during the previous 3 weeks
  • Presence of intraocular pathology: ocular hypertension, glaucoma, retinal vasculopathy or other retinal diseases
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00275756

Contacts
Contact: Gerhard Garhofer, MD + 43 1 40400 2981 gerhard.garhoefer@meduniwien.ac.at

Locations
Austria
Department of Clinical Pharmacology Not yet recruiting
Vienna, Austria, A-1090
Sponsors and Collaborators
Medical University of Vienna
Investigators
Principal Investigator: Gabriele Fuchsjaeger-Mayrl, MD Department of Clinical Pharmacology
  More Information

No publications provided

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

Keywords provided by Medical University of Vienna:
Glaucoma
Brimonidine
Timoptic
Dorzolamide
ocular blood flow

Additional relevant MeSH terms:
Glaucoma
Ocular Hypertension
Eye Diseases
Brimonidine
Dorzolamide
Antihypertensive Agents
Cardiovascular Agents
Therapeutic Uses
Pharmacologic Actions
Adrenergic alpha-2 Receptor Agonists
Adrenergic alpha-Agonists
Adrenergic Agonists
Adrenergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Physiological Effects of Drugs
Carbonic Anhydrase Inhibitors
Enzyme Inhibitors

ClinicalTrials.gov processed this record on September 16, 2014