At every step, samples are taken from the conjunctiva with a standard dissolving Ca-alginate swab (Sanofi-Pasteur, Germany). The moistened swab should be taken via one rotational swipe over the lower conjunctiva without touching the lid or eyelashes. Additionally anterior chamber aqueous fluid will be obtained immediately before and after surgery. The cannulas (2x) used for the aspiration will be cultured in a separate broth culture, too.