An interventional study of Timolol (drug) and dorzolamide (drug) in Glaucoma, sponsored by Medical University of Vienna. Withdrawn at 1 site in Austria. Open to participants aged 19 Years to 35 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2014-11-21.
Sponsored by Medical University of Vienna · Not applicable, Interventional, and Basic science
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.
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Exclusion Criteria:
Drug: Timolol (drug) · Device: Laser Doppler flowmetry · Device: Goldmann applanation tonometer · Procedure: Suction cup method
Drug: dorzolamide (drug) · Device: Laser Doppler flowmetry · Device: Goldmann applanation tonometer · Procedure: Suction cup method
Drug: brimonidine (drug) · Device: Laser Doppler flowmetry · Device: Goldmann applanation tonometer · Procedure: Suction cup method
Timolol (0.5%, non-selective beta-blocker, Timoptic®, Merck Sharp \& Dohme, Haarlem, Netherlands), dose 1 drop in one eye twice daily for two weeks
Dorzolamide (2%, carbonic anhydrase inhibitor, Trusopt®, Laboratoires Merck Sharp \& Dohme - Chibret, France), dose: 1 drop in one eye twice daily for two weeks
Brimonidine (0.2%. alpha-2 adrenergic agonist, Alphagan®, Allergan Pharmaceuticals, Westport, Ireland), dose: 1 drop in one eye twice daily for two weeks
blood flow measurements at the temporal neuroretinal rim of the optic nerve head, in total 4x 9 minutes on 2 study days
intraocular pressure measurements, in total 2x 5 measurements on two study days
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
Ocular perfusion pressure - ONH blood flow relationship
Time frame: on 2 study days
Composite measure: Blood pressure, heart rate
Time frame: on 2 study days
This study is withdrawn, 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