1. a Department of Ophthalmology , The Johns Hopkins University School of Medicine , Baltimore , MD
2. c Department of Epidemiology, Center for Clinical Trials , The Johns Hopkins University Bloomberg School of Public Health , Baltimore , MD
3. d Medstar Research Institute , Hyattsville , MD
4. e Department of Ophthalmology , University of California , San Francisco , CA
5. f Department of Ophthalmology , Northwestern University , Chicago , IL , USA
6. b Department of Medicine , The Johns Hopkins University School of Medicine , Baltimore , MD