1. Illinois Eye and Ear Infirmary, Department of Ophthalmology and Visual Science, College of Medicine, Department of Epidemiology and Biostatistics, School of Public Health, University of Illinois at Chicago, Chicago, IL, USA
2. Southern California Eye Institute, CHA Hollywood Prebyterian Medical Centre, Los Angeles, CA, USA
3. Department of Preventive Medicine, Keck School of Medicine of USC, Los Angeles, CA, USA