1. Department of Ophthalmology, Division of Hematology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
2. Department of Medicine, Division of Hematology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
3. Department of Ophthalmology, Division of Hematology, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Bangkok, Thailand.
4. Department of Medicine, Division of Hematology, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Bangkok, Thailand.