1. Department of Ophthalmology, University Medical Center of the Johannes Gutenberg-University Mainz, 55131 Mainz, Germany
2. Regiomed Clinic Masserberg, 98666 Masserberg, Germany
3. Department of Anaesthesiology, Hospital Worms, 67550 Worms, Germany
4. Department of Ophthalmology, University of Cologne, 50937 Cologne, Germany