1 Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts Departments of Neurology and Neurotherapeutics and Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas Departments of Ophthalmology and Neurology, University of Utah School of Medicine, Salt Lake City, Utah Department of Ophthalmology, University of Pennsylvania Scheie Eye Institute, Philadelphia, Pennsylvania Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania Division of Ophthalmology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.