Tear Film Compositional Characteristics And Its Influence On Tear Film Dynamics

Abstract

Abstract: : Purpose: The tear film dynamics (break up characteristics and stability) have been reported to be influenced by the complex lipid layer composition and possibly its interaction with lipocalin. The aims of the investigation were i. To optimise the analysis techniques to characterise low volume individual unstimulated tear samples; ii. To identify the compositional characteristics that control tear film dynamics. Methods: Tear lipids were analysed by HPLC using a normal phase column (LiChrospher Si60) - a polar mobile phase and dual UV/Fluorescence detector. 22 individual lipids were detected using 2 µl samples. Lipocalin was analysed by two-dimensional electrophoresis using non-linear immobilised pH gradient gels and SDS-PAGE minigel with silver stain. Lipocalin was quantified using 1 µl samples. Results: Analysis of the tear film of a large population (n=158) of normal subjects showed: i. High levels of cholesterol esters are associated with a thin inefficient lipid layer (p<0.05); ii. High levels of phospholipids are associated with stable tear film (p<0.05); iii. Lipocalin is beneficial to tear dynamics (p<0.05). Conclusion: The compositional analysis of individual tear films could be used to screen out patients with poor tear film dynamics, that are at risk of exhibiting dry eye symptoms. Such screening would be particularly beneficial prior to procedures that increase dry eye problems such as contact lens wear or LASIK.

Keywords: 376 cornea: tears/tear film/dry eye • 458 lipids