Received: 12 December 2017
Accepted: 17 August 2018
First Online: 28 August 2018
Ethics approval and consent to participate
: This study followed the tenets of the Declaration of Helsinki and approved by the ethics committee of the Department of Ophthalmology, Peking University International Hospital. Informed written consent was obtained from all participants.
: Not Applicable.
: The authors declare that they have no competing interests
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.