Submitted for Publication: October 4, 2011; final revision received April 18, 2012; accepted April 25, 2012.
Published Online: August 13, 2012. doi:10.1001/archophthalmol.2012.2147
Author Contributions: Dr Lewallen had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Financial Disclosure: None reported.
Additional Contributions: Survey data were collected and provided by Fernando Barria, MD; Marcelino Rio, MD; Felipe Chiriboga, MD; Karin Casasola, BA; Pedro A. Gómez B, MD; Luis H. Pongo, MD; Juan Batlle, MD, MS; Felipe Siso, MD; Maria Eugenia Nano, BA, MPH; Jorge Kleisinger, MD; and Carlos Arieta, MD, PhD. The Fred Hollows Foundation supported the development of the model software. Anne Clark and Talithia Williams provided statistical help.