Text and Data Mining valid from 2019-01-07
Received: 4 October 2018
Accepted: 4 December 2018
First Online: 7 January 2019
Compliance with Ethical Guidelines
: O. Findl is a scientific advisor for Carl Zeiss Meditec AG, N. Hirnschall receives presentation fees from Carl Zeiss Meditec AG, but both have no personal interest in the products mentioned. C. Leisser, N. Hirnschall, M. Ullrich, and O. Findl declare that they have no competing interests.
: All the research and measurements followed the tenets of the Declaration of Helsinki and were approved by the local ethics committee. Written informed consent was obtained from all study participants.