**Acknowledgements**

Thanks to my wife, Wenzhe Li, who dedicated her precious time to help when I finish this manuscript. Also, this research was supported by the Chinese Capital Clinical Features Key Project—Clinical Application on Chinese Keratoprosthesis (Project No: Z161100000516012), National Natural Science Foundation of China (Grant No. 81770887), and National Natural Science Foundation of China (Grant No. 81670830).
