1. Center for Ophthalmology, Department of Neuroophthalmology and Strabismus, University of Duisburg-Essen, Essen, Germany
2. Department of Surgery and Center for Minimal Invasive Surgery, Huyssen-Stift Essen, Essen, Germany
3. Center for Internal Medicine, Department of Endocrinology, University of Essen, Essen, Germany
4. Center for Internal Medicine, Department of Endocrinology, Diabetology and Rheumatology, University Duesseldorf, Duesseldorf, Germany