Ocular Blood Flow in Early Glaucoma Patients Before and After Treatment With Dorzolamide

July 23, 2007 updated by: University Health Network, Toronto

Ocular Blood Flow Measured by HRF and CLBF in Newly Diagnosed and Early Glaucoma Patients Before and After Instillation of Dorzolamide 2%

Impaired ocular blood flow is an important risk factor in the pathogenesis of primary open angle glaucoma (POAG). A few studies suggest that topical dorzolamide 2% may increase optic nerve perfusion. The objectives of this study are to learn the effects of dorzolamide on the retinal and optic nerve blood flow of glaucoma patients.

The present study is a prospective, randomized, double-masked, crossover design study of newly diagnosed or already treated patients with early glaucoma.

The investigators will check ocular blood flow parameters using the Canon Laser Blood Flowmeter (CLBF), used to evaluate retinal arteriole blood flow, and the Heidelberg retinal flowmeter (HRF), which measures blood flow through capillary beds in the retina and optic nerve head.

Any demonstrated improvements to retinal and optic nerve blood flow with dorzolamide, will mean that the drug may protect against ischaemic nerve and retinal damage. Any documented improvement in flow could lead to a major change in the management of glaucoma patients as well as other retinal ischemic diseases such as diabetic retinopathy and central retinal vein occlusion.

Study Overview

Status

Unknown

Conditions

Intervention / Treatment

Detailed Description

High intraocular pressure (IOP) is the major risk factor for glaucoma. Lowering intraocular pressure is still the only accepted form of treatment for glaucoma.

Over the past decade, epidemiological and experimental evidence suggested that impaired ocular blood flow is an important risk factor with an important role in the pathogenesis of primary open angle glaucoma (POAG). Several studies suggest that ischemia-promoting vascular factors may contribute to glaucomatous damage including vasospasm, impaired ocular perfusion pressure and general vascular disorders such as low blood pressure, especially dips in blood pressure at night.

Different techniques are employed to assess vascular dysfunction in the eye. As the methodology of ocular blood flow assessment is complex and differs in various aspects (e.g. target tissue and physiological parameters), comparative studies are required in order to enhance the interpretation of these measurements.

Our laboratory has state of the art equipment to assess ocular blood flow. One study done by us suggested that one drop of Dorzolamide 2% does not improve retinal blood flow in normal eyes. In the present study we plan to extend this study to 2 weeks of treatment in patients with POAG.

Dorzolamide hydrochloride 2% is a topical carbonic anhydrase inhibitor which reduces intraocular pressure (IOP) by decreasing the production of aqueous humour. Pharmacological studies on volunteers and glaucoma patients, using Color Doppler Imaging (measuring the retrobulbar blood flow) and Scanning laser Ophthalmoscopy (measuring arteriovenous passage time), indicate that topically applied Dorzolamide may increase perfusion of the optic nerve and peripapillary retina.

Study Type

Interventional

Enrollment (Anticipated)

17

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Ontario
      • Toronto, Ontario, Canada
        • Recruiting
        • Department of Ophthalmology and Visual Sciences; Toronto Western Hospital
        • Contact:
        • Contact:
        • Sub-Investigator:
          • Rony Rachmiel, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

20 years to 80 years (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  1. Males or females 20-80 years of age.
  2. Presence of typical early glaucomatous optic disc changes (cup/disc ratio ≤ 0.75) and/or early glaucomatous visual field defects (mean deviation less than 5dB and outside of 10° from fixation) in the study eye at the baseline visit.
  3. Best corrected visual acuity of at least 20/40.
  4. Signed informed consent from the subject
  5. The subject should be able to understand the instructions and perform the HRF and CLBF tests as well as be willing and able to comply with the study schedule and treatment.

Exclusion Criteria:

  1. Pregnant women or nursing mothers.
  2. Any other active ocular disease (ocular infections, Uveitis, etc.)
  3. Known allergy or sensitivity to the study medications.
  4. Functionally significant visual field loss (mean deviation greater than 5dB) or cup/disc ratio greater than 0.75 or evidence of progressive visual field loss within the last 6 months.
  5. Required chronic use of other ocular or systemic hypotensive medications during the study, other than the study medication (e.g. beta-blockers, Ca-channel blockers)
  6. Vascular occlusive disease affecting the ocular circulation such as: diabetic retinopathy, central retinal vein occlusion, central retinal artery occlusion, or non-arteritic ischemic optic neuropathy.
  7. Previous intraocular surgery or ocular traumas.
  8. Any past history of serious systemic condition affecting cerebral circulation including: hypertension, diabetes, cerebral vascular accident (CVA), or coronary artery bypass graft (CABG).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: DIAGNOSTIC
  • Allocation: RANDOMIZED
  • Interventional Model: CROSSOVER
  • Masking: SINGLE

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Ocular blood flow measurements

Secondary Outcome Measures

Outcome Measure
Intraocular pressure reduction

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University Health Network, Toronto

Collaborators

Merck Frosst Canada Ltd.

Investigators

  • Principal Investigator: Graham E Trope, MB, FRCSC, University of Toronto, Department of Ophthalmology
  • Study Chair: Chris Hudson, PhD, Department of Ophthalmology, Toronto Western Hospital, Toronto
  • Study Chair: John Flanagan, PhD, Department of Ophthalmology, Toronto Western Hospital, Toronto
  • Study Chair: Yvonne M Buys, MD, FRCSC, University of Toronto, Department of Ophthalmology, Toronto Western Hospital, Toronto

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

May 1, 2005

Study Completion

June 1, 2006

Study Registration Dates

First Submitted

September 8, 2005

First Submitted That Met QC Criteria

September 8, 2005

First Posted (ESTIMATE)

September 9, 2005

Study Record Updates

Last Update Posted (ESTIMATE)

July 25, 2007

Last Update Submitted That Met QC Criteria

July 23, 2007

Last Verified

September 1, 2005

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 04-0645-A

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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