1. Department of Biomedical Sciences, School of Medicine, Debre Markos University, Debre Markos, Ethiopia
2. Department of Medical Physiology, School of Medicine, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
3. Department of Ophthalmology, School of Medicine, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
4. Public Health Department, Saint Paul’s Hospital Millennium Medical College, Addis Ababa, Ethiopia