- ICH GCP
- US Clinical Trials Registry
- Clinical Trial NCT00262626
The Canadian Glaucoma Study
A Multicentre Study on the Risk Factors for the Progression of Open-Angle Glaucoma
Study Overview
Status
Conditions
Intervention / Treatment
Detailed Description
Elevated intraocular pressure is the most important known risk factor for the development and progression of open-angle glaucoma. While pressure reduction is beneficial in many cases, a significant proportion of patients continue to progress despite clinically acceptable pressure levels. Many investigators have found no differences in pressure characteristics between progressing and non-progressing patients, highlighting our current inability to identify which patients will respond to pressure reduction. It is likely that this inability stems from our poor understanding of the risk factors, both ocular and systemic, for progression and the probability that glaucoma is a disease with multiple pathogenic mechanisms.
In this application the Canadian Glaucoma Study Group proposes a multi-centre prospective study with the objective of characterising the risk factors associated with the progression of open-angle glaucoma. We will determine sub-groups of patients with regard to the type of progression, thereby allowing us to identify the ocular and systemic profiles of patients who are likely to and not likely to benefit from intraocular pressure reduction.
Our hypotheses are:
(i) The relationship between intraocular pressure characteristics during follow-up and survival rates with regard to progression of open-angle glaucoma is weak.
(ii) Patients with vasospasm have a higher survival rate than patients without vasospasm with the clinical management prescribed in this study.
(iii) Patients with vascular disease have a lower survival rate than patients without vascular disease with the clinical management prescribed in this study.
We will test these hypotheses by following a total of 410 patients in 4 centres (Halifax, Vancouver, Montreal and Toronto) every 4 months for a period of 5 years using a uniform protocol for both the clinical management and study procedures. Clinical management will involve at least 30% reduction in intraocular pressure from the baseline untreated value, followed by an additional 20% or greater reduction after a progressive event. The study procedures include conventional perimetry, blue-on-yellow perimetry and scanning laser tomography of the optic nerve head and nerve fibre layer. We will measure finger blood flow with both heat and cold provocation to assess each patient's susceptibility to vasospasm and also obtain haematological, biochemical and rheological profiles to assess the presence of vascular disease.
Progression of either visual field and optic nerve head damage will be termed a progressive event occurring after a predefined change from baseline. Events will be defined separately for each technique based on percentiles of empirically derived values of test-retest variability, allowing a degree of standardisation between techniques. Comparison of survival times between groups (e.g. vasospastic and non-vasospastic) will be made with Cox's survivorship analysis with a repeated measures model. Where appropriate, group comparisons will be made with the group t-test or Mann-Whitney test.
If we can characterise more fully the risk factors for glaucomatous progression, we may be able to identify the ocular and systemic profiles of patients who will benefit from our current treatment of pressure reduction. More importantly, we can identify the profiles of patients who respond poorly to pressure reduction so that future research efforts can lead to the development and implementation of alternative therapy. We believe that this is a significant study which will result in a better understanding of open-angle glaucoma and help reduce its impact on blindness and visual disability.
Study Type
Enrollment
Phase
- Not Applicable
Contacts and Locations
Study Locations
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British Columbia
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Vancouver, British Columbia, Canada, V5Z 3N9
- University of British Columbia
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Nova Scotia
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Halifax, Nova Scotia, Canada, B3H 2Y9
- Dalhousie University
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Ontario
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Toronto, Ontario, Canada, M5T 2S8
- University of Toronto
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Quebec
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Montreal, Quebec, Canada, H1T 2H1
- University of Montreal
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Participation Criteria
Eligibility Criteria
Ages Eligible for Study
Accepts Healthy Volunteers
Genders Eligible for Study
Description
Inclusion Criteria:
- Best corrected visual acuity of at least 6/9.
- Previous visual field examinations showing nerve fibre bundle visual field defects characteristic of open-angle glaucoma and/or previous optic nerve head photographs showing cupping or notching characteristic of open-angle glaucoma.
- Total visual field damage [in the eligibility visual field (see Section 6.1)] of between 2 and 10 dB using the visual field index Mean Deviation.46
- Access to patient's previous ocular history and availability of initial untreated intraocular pressure (minimum of three readings).
(d) Normal non-closable angles by gonioscopy. (e) Willingness to participate in the study and to give informed consent.
Exclusion Criteria:
- Non-glaucomatous ocular disease.
- Systemic disease known to affect the visual field or ability to participate in the study.
- Systemic beta-blockers.
- Chronic ocular medication other than for glaucoma.
- Previous incisional ocular surgery.
(e) Distance refraction exceeding 6.00 diopters equivalent sphere or 2.50 diopters of astigmatism.
(f) Aphakia or pseudophakia. (g) Contact lens wear.
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Prevention
- Allocation: Non-Randomized
- Interventional Model: Single Group Assignment
- Masking: None (Open Label)
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
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Visual field progression
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Secondary Outcome Measures
Outcome Measure |
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Optic disc progression
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Collaborators and Investigators
Sponsor
Collaborators
Investigators
- Principal Investigator: Balwantray C Chauhan, Ph.D., Dalhousie University
Publications and helpful links
General Publications
- Chauhan BC, Mikelberg FS, Artes PH, Balazsi AG, LeBlanc RP, Lesk MR, Nicolela MT, Trope GE; Canadian Glaucoma Study Group. Canadian Glaucoma Study: 3. Impact of risk factors and intraocular pressure reduction on the rates of visual field change. Arch Ophthalmol. 2010 Oct;128(10):1249-55. doi: 10.1001/archophthalmol.2010.196. Epub 2010 Aug 9. Erratum In: Arch Ophthalmol. 2010 Dec;128(12):1633.
- Chauhan BC, Mikelberg FS, Balaszi AG, LeBlanc RP, Lesk MR, Trope GE; Canadian Glaucoma Study Group. Canadian Glaucoma Study: 2. risk factors for the progression of open-angle glaucoma. Arch Ophthalmol. 2008 Aug;126(8):1030-6. doi: 10.1001/archopht.126.8.1030. Erratum In: Arch Ophthalmol. 2008 Oct;126(10):1364.
Study record dates
Study Major Dates
Study Start
Study Completion
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Estimate)
Study Record Updates
Last Update Posted (Estimate)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Additional Relevant MeSH Terms
Other Study ID Numbers
- CGS1
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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