1. Ophthalmology, Amsterdam Public Health research institute Amsterdam UMC Vrije Universiteit Amsterdam Amsterdam the Netherlands
2. Stichting Buurtzorg Nederland Almelo The Netherlands
3. Albert Schweitzer hospital Dordrecht The Netherlands
4. Department of Research Methodology, Measurement and Data Analysis Faculty of Behavioural, Management & Social Sciences University of Twente Enschede The Netherlands
5. Radboud University Medical Center, Ophthalmology Nijmegen The Netherlands
6. Elkerliek Hospital, Ophthalmology Helmond The Netherlands