1. Department of Ophthalmology, Penteli General Hospital for Children, Athens
2. First Ophthalmology Department, “G. Gennimatas” Hospital, National and Kapodistrian University of Athens,Athens, Greece
3. School of Science and Technology, Hellenic Open University, Patras, Greece
4. Department of Hygiene and Epidemiology, University of Thessaly, Larissa, Greece