1. Department of Medical Physiology, College of Medicine and Health Science, Bahir Dar University, Bahir Dar, Ethiopia
2. Department of Medical Physiology, College of Health Sciences, School of Medicine, Addis Ababa University, Addis Ababa, Ethiopia
3. Department of Ophthalmology, College of Health Sciences, School of Medicine, Addis Ababa University, Addis Ababa, Ethiopia