Department of Ophthalmology, Chinese PLA General Hospital & Chinese PLA Medical School, 28 Fuxing Road, Beijing 100853, People's Republic of China; Department of Ophthalmology, The 306th Hospital of Chinese PLA, 9 North Anxiang Road, Beijing 100101, People's Republic of China. Institute of Oncology, Key Laboratory of Oncology, Cancer Center, Division of Internal Medicine, Chinese PLA General Hospital & Chinese PLA Medical School, 28 Fuxing Road, Beijing 100853, People's Republic of China. Department of Ophthalmology, Chinese PLA General Hospital & Chinese PLA Medical School, 28 Fuxing Road, Beijing 100853, People's Republic of China. Department of Ophthalmology, Chinese PLA General Hospital & Chinese PLA Medical School, 28 Fuxing Road, Beijing 100853, People's Republic of China. Electronic address: zmn301@sina.com.