1. Department of Pediatrics and Child health, College of Medicine and Health Science, University of Gondar, Gondar, Ethiopia
2. Department of Ophthalmology, College of Medicine and Health Science, University of Gondar, Gondar, Ethiopia
3. Department of Pathology, College of Medicine and Health Science, University of Gondar, Gondar, Ethiopia
4. Department of Pediatrics, University of California San Francisco, San Francisco, CA 94117, USA