Canadian Glaucoma Study: 1. Study design, baseline characteristics, and preliminary analyses.
BACKGROUND
The Canadian Glaucoma Study is a multicentered, prospective longitudinal study designed to study a variety of systemic risk factors for the progression of open-angle glaucoma under a standardised interventional protocol for intraocular pressure (IOP) control.


METHODS
Newly or previously diagnosed patients with early to moderate open-angle glaucoma were recruited consecutively from 5 hospital-based university departments. Baseline parameters, including an assessment of peripheral vasospasm, haematologic, coagulation, and immunopathologic variables were obtained. Newly diagnosed patients were targeted for a >or=30% reduction in IOP, whereas previously diagnosed patients entered the study at a physician-defined target IOP. After baseline examinations, patients were followed at 4-month intervals with standard automated perimetry, short-wavelength automated perimetry, and confocal scanning laser tomography, and at 28-32-month intervals with stereo disc photography. If the patient had visual field progression with standard automated perimetry, a further >or=20% reduction in IOP was mandated. A standardized IOP treatment protocol, ranging from topical monotherapy to filtration surgery, was implemented.


RESULTS
A total of 258 patients (131 [corrected] men and 127 [corrected] women, median age 65.0 years) were enrolled. Baseline median values for visual acuity, visual field mean deviation, untreated IOP, and refractive error were 0.10 logMAR, -4.04 dB, 25.0 mm Hg, and 0.00 D, respectively. Approximately 30% of the patients were hypertensive, 16% had cardiovascular disease, 9% thyroid disease, 9% diabetes, 14% migraine, and 19% were smokers. The median follow-up was 5.3 years, with 148 (57.0%) and 51 (19.8%) patients completing >or=5 and >or=7 years follow-up, respectively. The cumulative visual field progression rate at 2, 4, 6, and 8 years was 11.3%, 21.5%, 33.1%, and 43.5%, respectively.


CONCLUSIONS
We describe the study design and baseline patient characteristics of the Canadian Glaucoma Study and present some preliminary results. This long and close follow-up of a large group of patients will reveal the importance of several systemic factors for the progression of glaucoma.
Department of Ophthalmology and Visual Sciences, Dalhousie University, Queen Elizabeth II Health Sciences Centre, Halifax, Novia Scotia, Canada. bal@dal.ca
D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology; D003329:Coronary Vasospasm / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005385:Fingers / Q000098:blood supply; D005902:Glaucoma, Open-Angle / Q000188:drug therapy / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D007429:Intraocular Pressure; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000473:pathology; D009901:Optic Nerve Diseases / Q000503:physiopathology*; D011446:Prospective Studies; D012107:Research Design; D012307:Risk Factors; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields