1. Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway
2. The Norwegian Dry Eye Clinic, Oslo, Norway
3. Department of Ophthalmology, Arendal Hospital, Arendal, Norway
4. Department of Oral Surgery and Oral Medicine, Dentistry, University of Oslo, Oslo, Norway
5. Faculty of Health Sciences, National Centre for Optics, Vision and Eye Care, University College of Southeast Norway, Kongsberg, Norway
6. Department of Clinical and Experimental Medicine; Ophthalmology, Linköping University, Linköping, Sweden
7. Department of ophthalmology, University Hospital North Norway, Tromsø, Norway
8. Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA