1. Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States
2. Department of Bioscience, New England College of Optometry, Boston, Massachusetts, United States
3. Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States
4. Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia, United States