1. Glaucoma Unit, 1st University Department of Ophthalmology, AHEPA Hospital, Thessaloniki - Greece
2. Department of Hygiene, Aristotle University of Thessaloniki, Thessaloniki - Greece
3. Eye Clinic, San Paolo Hospital, University of Milan, Milan - Italy
4. University Eye Clinic Maastricht, University Hospital Maastricht, Maastricht - The Netherlands