1. Department of Epidemiology and the Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland;
2. Division of General Internal Medicine, Department of Medicine, Johns Hopkins University, Baltimore, Maryland;
3. Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland;
4. Department of Laboratory Medicine and Pathology, Medical School, University of Minnesota, Minneapolis, Minnesota;
5. Merck and Company, Inc., Whitehouse Station, New Jersey;
6. Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Madison, Wisconsin;
7. Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia;
8. Singapore Eye Research Institute, National University of Singapore, Singapore.