1Department of Ophthalmology, University of Bonn, Bonn, Germany
2Department of Ophthalmology, University of Muenster, Muenster, Germany
3Department of Ophthalmology, St. Franziskus Hospital, Muenster, Germany
4Department of Ophthalmology, University of Muenster Domagkstr. 15, D-48149 Muenster, Germany