1. Department of Plastic and Reconstructive Surgery Oslo University Hospital Oslo Norway
2. Department of Medical Biochemistry Oslo University Hospital Oslo Norway
3. Department of Ophthalmology University of Groningen, University Medical Center Groningen Groningen The Netherlands
4. Department of Ophthalmology Sørlandet Hospital Arendal Arendal Norway
5. Department of Ophthalmology Oslo University Hospital Oslo Norway
6. Department of Ophthalmology King's College London, St Thomas' Hospital London UK
7. Department of Twin Research & Genetic Epidemiology King's College London, St Thomas' Hospital London UK
8. Dutch Dry Eye Clinic Velp The Netherlands
9. Department of Epidemiology University of Groningen, University Medical Center Groningen Groningen The Netherlands
10. Department of Ophthalmology Vestfold Hospital Trust Tønsberg Norway