1. From the Departments of Ophthalmology and 2Neurology, University of Iowa, College of Medicine, Iowa City VA Health Care, Iowa City, Iowa; the
2. Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, Iowa; and the
3. Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
4. From the Departments of Ophthalmology and