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

Medical University of Vienna

Status: Withdrawn

Conditions: Glaucoma

Treatments: Procedure: Suction cup method; Drug: dorzolamide (drug); Device: Goldmann applanation tonometer; Drug: brimonidine (drug); Device: Laser Doppler flowmetry; Drug: Timolol (drug)

Study type: Interventional

Funder types: Other

Identifiers

NCT00275756

OPHT-040106

Details and patient eligibility

About

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.

Sex: All

Ages: 19 to 35 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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0 participants in 3 patient groups

1

Experimental group

Treatment:

Device: Laser Doppler flowmetry

Drug: Timolol (drug)

Device: Goldmann applanation tonometer

Procedure: Suction cup method

2

Experimental group

Treatment:

Device: Laser Doppler flowmetry

Device: Goldmann applanation tonometer

Drug: dorzolamide (drug)

Procedure: Suction cup method

3

Experimental group

Treatment:

Device: Laser Doppler flowmetry

Drug: brimonidine (drug)

Device: Goldmann applanation tonometer

Procedure: Suction cup method