Siamak Sabour1,2, Fariba Ghassemi3. 1. Safety Promotion and Injury Prevention Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. s.sabour@sbmu.ac.ir. 2. Department of Clinical Epidemiology, School of Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran. s.sabour@sbmu.ac.ir. 3. Department of Retina, Farabi Eye Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.