Article History
Received: 10 January 2018
Accepted: 13 April 2018
First Online: 9 May 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.
: The authors declare that they have no competing interests.
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