1. Prevention of Blindness Program, Ministry of Public Health & Population, Sana’a, Yemen
2. Department of Ophthalmology, College of Medicine, University of Sana’a, Sana’a, Yemen
3. Eye Unit, Al-Thawra Hospital, Sana’a, Yemen
4. Faculté de Médecine et des Sciences Biomédicales, Université de Yaoundé I, Yaoundé, Cameroun
5. Communicable Diseases Prevention, Control, and Elimination, Pan American Health Organization, Washington, USA
6. Global Neglected Tropical Diseases Programme, World Health Organization, Geneva, Switzerland