Tear Film Lipid Composition of Schirmer Strips from Patients With and Without Dry Eyes

Abstract

Abstract: : Purpose: The tear film lipid layer is believed to stabilize the tear film by preventing evaporation. We characterized lipid and protein deposited on Schirmer strips to determine compositional differences associated with patients with dry eye symptoms. Methods: Schirmer strips were collected from patients with and without dry eye symptoms. Samples were grouped as: no dry eye, dry eye, dry eye treated with saline eye drops, dry eye treated with antibiotics. Attenuated Reflectance Spectroscopy (ATR) was used to characterize compositional changes on Schirmer strips. The composition of lipid extracted from Schirmer strips was measured using matrix-assisted laser desorption ionization / time of flight mass spectrometry (MALDI / TOF MS). Results: Total lipid on Schirmer strips from all dry eye groups was significantly lower compared to the group without dry eye. Among the dry eye groups, the group treated with antibiotic exhibited significantly lower lipid on Schirmer strips. The intensity of the infrared amide and CH₂ stretching bands were significantly lower in ATR spectra of Schirmer strips from the dry eye groups indicating less lipid and protein. The ratio of the intensity of the OH/CH₂ infrared stretching bands was significantly higher in the dry eye groups indicating that Schirmer strips from the dry eye groups contained more protein relative to lipid. MALDI/ TOF MS data indicate that the relative amount of sphingomyelin decreases while the amount of the phosphatidylcholine increases. Conclusions: The composition, total and relative amount of lipid is lower on Schirmer strips from patients with dry eye symptoms. ATR and MALDI / TOF MS analysis of Schirmer strips may be useful for screening patients with dry eye symptoms and provide compositional information that may be useful in elucidating the etiology of dry eye symptoms.

Keywords: lipids • cornea: tears/tear film/dry eye • cornea: basic science