1. Health Centre “Sveti Đorđe” , Topola , Serbia
2. Clinic of ophthalmology , Clinical Centre Kragujevac , Kragujevac , Serbia
3. Faculty of Medical Sciences , University of Kragujevac , Kragujevac , Serbia
4. Department for Hospital Healthcare , Clinical Centre Kragujevac , Kragujevac , Serbia
5. Clinic of Otorhinolaryngology , Clinical Centre Kragujevac , Kragujevac , Serbia