1. The Second Hospital of Shanxi Medical University Taiyuan 030001 Shanxi P. R. China
2. Shanxi Province Cardiovascular Hospital Taiyuan 030024 Shanxi P. R. China
3. Shanxi Medical University Taiyuan 030001 Shanxi P. R. China
4. Schepens Eye Research Institute Massachusetts Eye and Ear Harvard Medical School Affiliate Boston MA 02114 USA