1. Department of Palliative Medicine, RWTH Aachen University, Germany, Department of Ophthalmology and Aachen Cornea Bank, RWTH Aachen University, Germany
2. Department of Ophthalmology and Aachen Cornea Bank, RWTH Aachen University, Germany
3. Department of Palliative Medicine, University Hospital, Bonn, and Malteser Hospital, Bonn, Germany