1. Department of Ophthalmology, The Second Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
2. Clinical Medical College, Second Military Medical University, Shanghai 200433, P.R. China
3. Bayi Children's Hospital Affiliated to PLA Army General Hospital, Beijing 100700, P.R. China
4. Department of Otolaryngology, The Second Hospital, Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China