1. Ophthalmology Clinic, Clinical Center Nis, Boulevard Zorana Djindjica 48, Nis 18000, Serbia e-mail:
2. Faculty of Occupational Safety, University of Nis, Carnojevica 10a, Nis 18000, Serbia e-mail:
3. Cardiovascular Clinic, Clinical Center Nis, Boulevard Zorana Djindjica 48, Nis 18000, Serbia e-mail: