Funding for this research was provided by:
Department of Science and Technology of Sichuan Province (2015JQ0026)
Article History
Received: 4 April 2018
Accepted: 28 July 2018
First Online: 21 August 2018
Compliance with ethical standards
:
: The authors declare that they have no conflicts of interest and nothing to disclose.
: Since this is a retrospective study, formal consent is not required. However, an informed consent was obtained from individual participants for taking and publishing photographs.