1. Department of Ophthalmology, University Hospital Essen, Essen, Germany;
2. Department of Radiotherapy, University Hospital Essen, Essen, Germany;
3. German Cancer Consortium (DKTK), Heidelberg, Germany, Partner Site University Hospital Essen, Essen, Germany; and;
4. Department of Ophthalmology, Hannover Medical School, Hannover, Germany.