1. Department of Ophthalmology, University of Muenster Medical Center, Muenster, Germany
2. Department of Ophthalmology, University of Würzburg, Würzburg, Germany
3. Institute of Biostatistics and Clinical Research, University of Muenster, Muenster, Germany
4. Eye Hospital Castrop-Rauxel, Castrop-Rauxel, Germany