1. Department of Neurology, Perelman School of Medicine, University of Pennsylvania, 3 W. Gates Building, 3400 Spruce Street, Philadelphia, PA 19104, USA
2. Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, 3 W. Gates Building, 3400 Spruce Street, Philadelphia, PA 19104, USA
3. Department of Epidemiology, Perelman School of Medicine, University of Pennsylvania, 3 W. Gates Building, 3400 Spruce Street, Philadelphia, PA 19104, USA