Evaluation of tear fluid production using Schirmers' tests is a well-known and frequently used examination method in ophthalmology. Schirmers' test objectively indicates the tear fluid production over five minutes by insertion of a filter paper strip in the lower conjunctival fornix. Commonly, this method is used to quantify tear fluid production, but not tear fluid composition. The development of novel, very precise analytical methods opens up new possibilities in the use and application of Schirmers' test strips. A recently introduced analytical method is mass spectrometry. This method allows the detection and quantification of proteins, lipids, and metabolites in very low amounts of samples. Whether systemically ingested agents such as omega-3 fatty acids or acetylsalicylic acid can be detected in tear fluid using this method remains unclear. The aim of this study is to investigate the detectability of 2 different agents (acetylsalicylic acid and omega-3 fatty acids) in Schirmers' test strips from healthy subjects after intake for 1 week by use of untargeted mass spectrometry. Participating healthy subjects will receive either acetylsalicylic acid or omega-3 fatty acids.

Inclusion Criteria:

• Men and women age of at least 18 years to 60 years
• Written informed consent prior to study-related procedures
• Normal ophthalmic findings
• No use of eye drops including topical lubricants in the 4 weeks before screening

Exclusion Criteria:

• Participation in a clinical trial in the 3 weeks preceding the study
• Symptoms of a clinically relevant illness in the 3 weeks before the first study day
• Presence or history of a severe medical condition as judged by the clinical investigator
• Intake of any drugs or dietary supplements within three weeks before the first study day (except contraceptives)
• TFBUT <10 sec.
• Glaucoma in the medical history
• Ocular infection or clinically significant inflammation
• Ocular surgery in the 3 months preceding the study
• Pregnancy, planned pregnancy or lactating
• Known hypersensitivity to any component of the study medication