1. Department of Ophthalmology, Penn State College of Medicine, Hershey, Pennsylvania
2. Department of Public Health Sciences, Penn State College of Medicine, Hershey, Pennsylvania
3. The Emmes Corporation, Rockville, Maryland
4. Doheny Eye Institute, University of California, Los Angeles
5. University of Wisconsin Fundus Photograph Reading Center, University of Wisconsin, Madison
6. Department of Ophthalmology and Visual Science, University of Wisconsin, Madison
7. The Retina Group of Washington, Fairfax, Virginia