1 Departments of Neurology and Ophthalmology, Stanford University, Palo Alto, California.
2 Departments of Neurology and Ophthalmology, University of Utah, Salt Lake City, Utah.
3 Departments of Neurology and Neurotherapeutics and Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas.
4 Departments of Neurology and Ophthalmology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania; Division of Ophthalmology, Neuro-ophthalmology Service, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: Liug1@email.chop.edu.