A Comparison of the Effect of Dorzolamide and Timolol on Optic Disk Blood Flow in Patients With Open Angle Glaucoma

Study Overview
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Brief Summary
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Glaucoma is one of the most common causes of blindness in the industrialized nations. For a long time glaucoma has been defined as a disease in which high intraocular pressure (IOP) leads to irreversible optic disk damage and concommitant visual field loss. However, recent investigations show that IOP is not necessarily an adequate measure of clinical severity or a predictor of clinical progression: about 20% of all eyes with high IOP do not develop visual field loss and some patients suffering from visual field loss due to optic disk damage have normal IOP. Hence, factors other than IOP are likely involved in the pathogenesis of glaucoma. The role of vascular factors in the pathogenesis of glaucoma has recently received much attention and optic nerve head hypoperfusion may play a critical role in the development of glaucoma. It may therefore be important for an optimal prevention of visual field defects in glaucoma that the topical antiglaucoma drugs used do not only reduce IOP but also stabilize or enhance the perfusion of the optic nerve head. Therefore, the aim of the present study is to compare the effect of a 3 months treatment with timolol or dorzolamide in patients with open angle glaucoma on optic disk blood flow.

Official Title
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A Double-masked Comparison of the Effect of Dorzolamide and Timolol on Optic Disk Blood Flow in Patients With Open Angle Glaucoma

Conditions
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Glaucoma, Open-Angle

Intervention / Treatment
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* Drug: Dorzolamide 2%
* Drug: Timolol 0.5%


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women older than 19 years Primary open angle glaucoma or ocular hypertension with IOP higher than 22 mmHg in at least one eye Washout period for previous antiglaucoma treatment: two weeks for adrenergic agonists, one week for parasympathomimetic agents Exclusion Criteria: Exfoliation glaucoma, pigmentary glaucoma History of acute angle closure Intraocular surgery or argon laser trabeculoplasty within the last 6 months Ocular inflammation or infection within the last 3 months Contact lenses Patients with bradycardia (heart rate less than 50 beats/min) Second or third degree heart block Asthma COPD Congestive Heart Failure Severe renal impairment (Creatinine clearance less than 1.8 l/h History or hypersensitivity to one of the study drugs or drugs with similar chemical structure History of non-IOP responder to beta-blockers or carbonic anhydrase inhibitors Pregnancy

Ages Eligible for Study
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Minimum Age: 19 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: 1<br>Patients with open angle glaucoma | Drug: Dorzolamide 2%<br> <br> |
| Active Comparator: 2<br>Patients with open angle glaucoma | Drug: Timolol 0.5%<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percent change over baseline after 3 months of treatment of optic disk blood flow measured with the Heidelberg Retina Flowmeter |  | 5 minutes measurement of optic disk blood flow on 3 study days | 
| Percent change over baseline after 3 months of treatment of fundus pulsation amplitude (FPA) in the optic disk as assessed with laser interferometry |  | 5 minutes measurement of FPA on 3 study days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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open angle glaucoma, timolol, dorzolamide