1. Department of Ophthalmology, Justus-Liebig-University Gießen, 35392 Gießen, Germany
2. Department of Mathematics, Natural Sciences and Data Processing, Technische Hochschule Mittelhessen, 61169 Friedberg, Germany
3. Department of Ophthalmology, University Hospital Bonn, 53127 Bonn, Germany
4. Institute of Applied Mathematics, University of Bonn, 53115 Bonn, Germany