1. Klinikum Bad Bramstedt; Bad Bramstedt Germany
2. Department of Medical Biometry and Statistics, University of Lübeck, University Hospital Schleswig-Holstein; Lübeck Germany
3. Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Schleswig-Holstein and Christian-Albrechts-University of Kiel; Kiel Germany
4. Department of Ophthalmology, University Hospital Schleswig-Holstein, Campus Kiel and Christian-Albrechts-University of Kiel; Kiel Germany