[1] Univ Calif San Francisco, Francis I Proctor Fdn, San Francisco, CA 94158 USA
[2] London Sch Hyg & Trop Med, London WC1E 7HT, England
[3] Univ Peruana Cayetano Heredia, Sch Publ Hlth & Adm, Emerge Emerging Dis & Climate Change Res Unit, Lima 15102, Peru
[4] Red Salud Alto Amazonas, Area Epidemiol, Yurimaguas 16501, Peru
[5] Inst Barraquer Amer, Escuela Super Oftalmol, Bogota 110111, Colombia
[6] Minist Salud, Componente Salud Ocular & Prevenc Ceguera, Lima 15072, Peru