1. Department of Ophthalmology, Erasmus University Medical Center, Rotterdam, The Netherlands
2. Department of Public Health, Erasmus University Medical Center, Rotterdam, The Netherlands
3. Division of Ear, Nose and Throat Disease, Karolinska Institute, Stockholm, Sweden
4. Independent consultant, Manchester, UK
5. School of Psychology and Clinical Language Sciences, University of Reading, Reading, UK
6. Department of Ophthalmology, Goethe University, Frankfurt am Main, Germany
7. School of Health and Related Research, University of Sheffield, Sheffield, UK