National RAAB; Sample size: 4011; Reference: Limburg H1, Barria von-Bischhoffshausen F, Gomez P, Silva JC, Foster A. Review of recent surveys on blindness and visual impairment in Latin America. Br J Ophthalmol. 2008 Mar;92(3):315-9. doi: 10.1136/bjo.2007.125906. Epub 2008 Jan 22. and Limburg H, Silva JC, Foster A. Cataract in Latin America: findings from nine recent surveys. Rev Panam Salud Publica. 2009;25(5):449–55.