Funding for this research was provided by:
Svenska Läkaresällskapet (SLS-504541)
Stiftelsen Kronprinsessan Margaretas Arbetsnämnd för Synskadade (2013/10)
Västerbotten County Council 'Spjutspetsmedel' (VLL-363161)
Federal funds through regional agreement (ALF) between Umeå University and Västerbotten County Council (VLL-549761)
Text and Data Mining valid from 2019-08-09
Received: 29 January 2019
Revised: 24 June 2019
Accepted: 31 July 2019
First Online: 9 August 2019
Compliance with ethical standards
: The study was vetted by the Regional Ethical Review Board in Umeå, which determined it to be exempt from the requirement for approval (2010-373-31M). The study was performed according to the principles of the Declaration of Helsinki.
: The authors declare that they have no conflict of interest.