Inclusion Criteria:  Age older than 22 years Corneal staining (marked to severe; NEI grading scale >=10)  Exclusion Criteria:  Usage of eye drops other than lubricants (e.g. antibiotics, steroids, cyclosporin-A) Usage of systemic antibiotic therapy Any pathology of the ocular surface except dry eye disease (e.g. corneal scarring, cornea ectasia) Ocular surgery within prior 3 months to screening Preceding refractive corneal surgery (e.g. LASIK) Ocular injury within prior 3 months Ocular herpes of eye or eyelid within prior 3 months Active ocular infection Active ocular inflammation or history of chronic, recurrent ocular inflammation within prior 3 months Eyelid abnormalities that affect lid function Ocular surface abnormality that may compromise corneal integrity Pregnancy and nursing women (in women of childbearing age a pregnancy test will be performed before inclusion into the study)