1. The Ohio State University; College of Optometry; 338 West Tenth Avenue Columbus Ohio USA 43210-1240
2. Johns Hopkins Bloomberg School of Public Health; Center for Clinical Trials, Department of Epidemiology; 615 North Wolfe Street, W5010 Baltimore Maryland USA 21205
3. Southern California College of Optometry; 2575 Yorba Linda Boulevard Fullerton California USA 92831
4. University of Arizona; Department of Ophthalmology; 655 North Alvernon Way Suite 108 Tucson Arizona USA 85711