1. Department of Orthoptics and Visual Sciences, Faculty of Medical Technology, Niigata University of Health and Welfare, Niigata 950-3198, Japan
2. Department of Vision Science, Faculty of Sensory and Motor Control, Kitasato University Graduate School of Medical Science, Sagamihara 252-0373, Japan
3. Department of Rehabilitation, Orthoptics and Visual Science Course, School of Allied Health Sciences, Kitasato University, Sagamihara 252-0373, Japan