1. Department of Ophthalmology, Tri-Service General Hospital and National Defense Medical Center, Taipei 114, Taiwan
2. Department of Ophthalmology, Buddhist Tzu Chi General Hospital, Hualien 970, Taiwan
3. Institute of Medical Sciences, Tzu Chi University, Hualien 970, Taiwan
4. Department of Medicine, Hualien Armed Forces General Hospital, Hualien 971, Taiwan
5. Department of Medicine, Tri-Service General Hospital and National Defense Medical Center, Taipei 114, Taiwan
6. Department of Preventive Medicine, Northwestern University, Chicago, IL 60611, USA