Hyeong Ju Byeon1, Keun Young Park2, Jin Sook Yoon1, JaeSang Ko3. 1. Department of Ophthalmology, Institute of Vision Research, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea. 2. Department of Neurosurgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea. 3. Department of Ophthalmology, Institute of Vision Research, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea. jaesangko@yuhs.ac.