1. Department of Ophthalmology, King’s College London, London, UK
2. Department of Community Health and Epidemiology, Dalhousie University, Halifax, Nova Scotia, Canada
3. MedMetrics Inc, Wolfville, Nova Scotia, Canada
4. Health Sciences Library, Memorial University, St John’s, Newfoundland, Canada
5. Ophthalmology Services, Department of Surgery, Northern Ontario School of Medicine and Thunder Bay Regional Health Sciences Centre, Thunder Bay, Ontario, Canada