1. Department of Ophthalmology, Faculty of Medicine, School of Health Sciences, University of Ioannina, Ioannina, Greece
2. First Department of Ophthalmology, General Hospital of Athens G. Gennimatas, Medical School, National and Kapodistrian University of Athens, Greece
3. Department of Ophthalmology, Faculty of Medicine, School of Health Sciences, University of Patras, Patras, Greece