1. Clinic of Social and Family Medicine, School of Medicine, University of Crete, 71003 Heraklion, Greece
2. Department of Ophthalmology, University Hospital of Heraklion, Crete, 71500 Heraklion, Greece
3. Clinic of Social and Family Medicine, Faculty of Medicine, University of Crete, 71003 Heraklion, Greece
4. Department of Ophthalmology, General Hospital of Ierapetra, 72200 Ierapetra, Greece
5. School of Medicine, University of Crete, 71003 Heraklion, Greece
6. Department of Social Medicine, Biostatistics Lab, School of Medicine, University of Crete, 71003 Heraklion, Greece