- Correspondence to Professor Rigmor C Baraas, National Centre for Optics, Vision and Eye Care, Faculty of Health Sciences, University College of Southeast Norway, Hasbergsvei 36, 3616 Kongsberg, Norway;
- Received 9 May 2017
- Revised 7 August 2017
- Accepted 9 September 2017
- Published online 19 October 2017.
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