1. Rotterdam Eye Hospital, Schiedamse Vest 180, 3011 BH Rotterdam, The Netherlands
2. Rotterdam Ophthalmic Institute, Schiedamse Vest 160, 3011 BH Rotterdam, The Netherlands
3. Radboud University Medical Center, Postbus 9101, 6500 HB Nijmegen, The Netherlands
4. Visser Contactlenzen, St. Annastraat 93, 6524 EJ Nijmegen, The Netherlands
5. National Institute for Public Health and the Environment (RIVM), Postbus 1, 3720 BA Bilthoven, The Netherlands