GlaucomaNCT00262626
The Canadian Glaucoma Study
A study testing Intraocular pressure reduction, Argon laser trabeculoplasty and Trabeculectomy in people with Glaucoma, run by Dalhousie University at 4 sites in Canada.
Trial summary
Glaucoma is a disease which affects between one and two percent of all individuals aged over 40 years. According to recent Canadian National Institute for the Blind figures, it is the second largest specific cause of blindness in this country. Read more about this study
- Who is it for?
- Ages 0 years and older
- Conditions the study is for
- Glaucoma
- What is being tested?
- Intraocular pressure reduction, Argon laser trabeculoplasty and Trabeculectomy
- Type of treatment
- Surgery or procedure
- How many people
- 430 participants
- Where
- 4 sitesCanada
- Study dates
- Feb 1995to Jun 1995
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 0 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- 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).
- Normal non-closable angles by gonioscopy. (e) Willingness to participate in the study and to give informed consent.
Who cannot join
- 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.
- Distance refraction exceeding 6.00 diopters equivalent sphere or 2.50 diopters of astigmatism.
- Aphakia or pseudophakia. (g) Contact lens wear.
Trial locations and contacts
4 sites in 1 country.
Canada4 sites
Dalhousie University
Halifax, Nova Scotia, B3H 2Y9
University of Montreal
Montreal, Quebec, H1T 2H1
University of Toronto
Toronto, Ontario, M5T 2S8
University of British Columbia
Vancouver, British Columbia, V5Z 3N9
About this study
Official title: A Multicentre Study on the Risk Factors for the Progression of Open-Angle Glaucoma
Glaucoma is a disease which affects between one and two percent of all individuals aged over 40 years. According to recent Canadian National Institute for the Blind figures, it is the second largest specific cause of blindness in this country. The most common form of glaucoma, open-angle glaucoma, is incipient and typically results in a progressive loss of vision without symptoms due to damage to a structure inside the eye called the optic nerve head. Although the most important known risk factor for the development of open-angle glaucoma is high intraocular pressure (the pressure within the eyeball), a number of researchers have shown that a sizeable proportion of patients continue to lose vision in spite of successful treatment to lower their intraocular pressure. This finding suggests that there may be additional risk factors involved. Ocular vasospasm (the inability of certain blood vessels to dilate and increase blood flow according to the needs the eye) and vascular disease are among other factors implicated but their roles have not yet been fully investigated. The Canadian Glaucoma Study Group proposes to investigate the role of risk factors, including vasospasm and vascular disease, involved in the progression of open-angle glaucoma. We will recruit 410 patients with open-angle glaucoma across 4 centres (Halifax, Vancouver, Montreal and Toronto) who will be treated by experienced investigative ophthalmologists according to a uniform standard protocol to ensure that all patients are managed in the same manner. The patients will be followed meticulously with the most modern and accurate tests available every four months for a period of 5 years to determine whether progression has taken place. Visual function will be measured using two techniques called conventional perimetry and blue-on-yellow perimetry, and optic nerve heads will be examined with a special scanner capable of three-dimensional imaging. By defining both the ocular and systemic profiles of patients who progress and do not progress, we may be able to identify which patients will benefit from the standard treatment of intraocular pressure reduction, such as that prescribed in the study. More importantly, we will identify the characteristics of patients who do not benefit from standard treatment, so that alternative ones may be developed. Such studies are clearly necessary, but have not yet been conducted. We believe that the proposed study will increase our knowledge of open-angle glaucoma and reduce its impact on blindness and visual disability.
Read the 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.
- Conditions
- Glaucoma
- Being tested
- Intraocular pressure reduction, Argon laser trabeculoplasty, Trabeculectomy
- Medical subject headings
- Glaucoma
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Intraocular pressure reductionDrug
Argon laser trabeculoplastyProcedure or surgery
TrabeculectomyProcedure or surgery
What is being measured
The primary outcome is the main question the study is designed to answer.
Visual field progression
Secondary outcomes (1)
Optic disc progression
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Dec 2005 (estimated)
- Study startFeb 1995
- Study completionJun 1995
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for GlaucomaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 430 participants
Sponsor and investigators
- Lead sponsor
- Dalhousie University
- Sponsor type
- University, hospital or other
- Collaborators
- Canadian National Institute for the Blind, Glaucoma Research Society of Canada, Allergan, Merck Frosst Canada Ltd., Pfizer
- Investigators
- Balwantray C Chauhan, Ph.D., Principal investigator, Dalhousie University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00262626
- Sponsor's protocol ID
- CGS1
- Status last verified
- Jun 2003
- First submitted
- 5 Dec 2005
- Last updated
- 7 Dec 2005
- Results posted
- No
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.
PubMed 20696979Chauhan 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.
PubMed 18695095
Study at a glance
From the registry record, last updated by the sponsor on 7 Dec 2005. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Multicentre Study on the Risk Factors for the Progression of Open-Angle Glaucoma
- ClinicalTrials.gov ID
- NCT00262626
- Acronym / sponsor ID
- CGS1
- Conditions
- Glaucoma
- Study type
- Interventional
- Recruitment status
- Terminated
- Enrolment
- 430 participants
- Lead sponsor
- Dalhousie UniversityUniversity, hospital or other
- Collaborators
- Canadian National Institute for the Blind, Glaucoma Research Society of Canada, Allergan, Merck Frosst Canada Ltd., Pfizer
- Study start
- Feb 1995
- Study completion
- Jun 1995
- First posted
- 7 Dec 2005 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Glaucoma is a disease which affects between one and two percent of all individuals aged over 40 years. According to recent Canadian National Institute for the Blind figures, it is the second largest specific cause of blindness in this country. The most common form of glaucoma, open-angle glaucoma, is incipient and typically results in a progressive loss of vision without symptoms due to damage to a structure inside the eye called the optic nerve head. Although the most important known risk factor for the development of open-angle glaucoma is high intraocular pressure (the pressure within the eyeball), a number of researchers have shown that a sizeable proportion of patients continue to lose vision in spite of successful treatment to lower their intraocular pressure. This finding suggests that there may be additional risk factors involved. Ocular vasospasm (the inability of certain blood vessels to dilate and increase blood flow according to the needs the eye) and vascular disease are among other factors implicated but their roles have not yet been fully investigated. The Canadian Glaucoma Study Group proposes to investigate the role of risk factors, including vasospasm and vascular disease, involved in the progression of open-angle glaucoma. We will recruit 410 patients with open-angle glaucoma across 4 centres (Halifax, Vancouver, Montreal and Toronto) who will be treated by experienced investigative ophthalmologists according to a uniform standard protocol to ensure that all patients are managed in the same manner. The patients will be followed meticulously with the most modern and accurate tests available every four months for a period of 5 years to determine whether progression has taken place. Visual function will be measured using two techniques called conventional perimetry and blue-on-yellow perimetry, and optic nerve heads will be examined with a special scanner capable of three-dimensional imaging. By defining both the ocular and systemic profiles of patients who progress and do not progress, we may be able to identify which patients will benefit from the standard treatment of intraocular pressure reduction, such as that prescribed in the study. More importantly, we will identify the characteristics of patients who do not benefit from standard treatment, so that alternative ones may be developed. Such studies are clearly necessary, but have not yet been conducted. We believe that the proposed study will increase our knowledge of open-angle glaucoma and reduce its impact on blindness and visual disability.
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 design
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
Who may qualify
- Ages
- 0 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (5 listed)
- 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).
- Normal non-closable angles by gonioscopy. (e) Willingness to participate in the study and to give informed consent.
Key exclusion criteria (7 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Intraocular pressure reduction | Drug | – |
| Argon laser trabeculoplasty | Procedure or surgery | – |
| Trabeculectomy | Procedure or surgery | – |
Primary outcome
Visual field progression
1 secondary outcome
Optic disc progression
Results and safety
The study was stopped early. Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Dec 2005.
- Derived from this study: PubMed 20696979Chauhan 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.
- Derived from this study: PubMed 18695095Chauhan 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.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Balwantray C Chauhan, Ph.D. principal investigator
Dalhousie University
4 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Intraocular pressure reduction, Argon laser trabeculoplasty and Trabeculectomy in people with Glaucoma, run by Dalhousie University at 4 sites in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 7 Dec 2005. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study was stopped early. Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Visual field progression. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT00262626, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Dec 2005.