[1] University of Toronto,Division of Health Promotion
[2] University of Toronto,Division of Clinical Public Health, Dalla Lana School of Public Health
[3] University of Toronto,Human Biology Program, Faculty of Arts & Science
[4] University of Toronto,Department of Ophthalmology and Vision Sciences, Faculty of Medicine
[5] The Hospital for Sick Children,Department of Ophthalmology and Vision Sciences
[6] SickKids Research Institute,Child Health Evaluative Sciences
[7] University of Nairobi,Department of Human Pathology, College of Health Sciences
[8] McMaster University,Present Address: Michael G. DeGroote Medical School