[1] Minist Publ Hlth & Populat, Prevent Blindness Program, Sanaa, Yemen
[2] Univ Sanaa, Coll Med, Dept Ophthalmol, Sanaa, Yemen
[3] Al Thawra Hosp, Eye Unit, Sanaa, Yemen
[4] Univ Yaounde I, Fac Med & Sci Biomed, Yaounde, Cameroon
[5] Pan Amer Hlth Org, Communicable Dis Prevent Control & Eliminat, Washington, DC USA
[6] WHO, Global Neglected Trop Dis Programme, Geneva, Switzerland