Received: 3 November 2017
Accepted: 21 February 2018
First Online: 26 March 2018
Compliance with ethical standards
: Myriam Böhm and Mehdi Shajari declare that they have no conflict of interest. Matthias Remy has received a travel honorarium from Avedro (Waltham, MA 02451, USA).
: This article does not contain any studies with animals performed by any of the authors. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
: No informed consent was obtained from patients since this was a retrospective study and data were anonymized. This is in accordance with the ethical vote obtained from the local ethics committee.