1 Temerty Faculty of Medicine (AH), University of Toronto, Toronto, Canada; Department of Ophthalmology & Vision Sciences (EI, AS, RAS), University of Toronto, Toronto, Canada; Department of Ophthalmology and Visual Sciences (EI), University of Alberta, Edmonton, Canada; Hurvitz Brain Sciences Research Program (AS), Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Canada; Division of Neurology (VB), University of Toronto, Toronto, Canada; and The Ellen & Martin Prosserman Centre for Neuromuscular Diseases (VB), University Health Network, University of Toronto, Toronto, Canada.