1. Department of Ophthalmology; The National University Hospital; Reykjavik Iceland
2. University of Iceland; Reykjavik Iceland
3. Department of Ophthalmology; Orebro University Hospital; Orebro Sweden
4. Family Medicine and Preventive Medicine Section; Department of Public Health and Caring Sciences; Uppsala University; Uppsala Sweden
5. Family Medicine Research Centre; Orebro County Council; School of Health and Medical Sciences; Orebro University; Sweden