Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. Jaeb Center for Health Research, Tampa, Florida, USA. Electronic address: drcrstat8@jaeb.org. University of Pennsylvania, Philadelphia, Pennsylvania, USA. Jaeb Center for Health Research, Tampa, Florida, USA. The Retina Institute, St Louis, Missouri, USA. Valley Retina Institute, McAllen, Texas, USA. Feinberg School of Medicine, Northwestern University Medical School, Chicago, Illinois, USA. Joslin Diabetes Center, Beetham Eye Institute, Harvard Department of Ophthalmology, Boston, Massachusetts, USA. Palmetto Retina Center, Columbia, South Carolina, USA.