A Novel Interferometric Device for Measurement of Tear Film Lipid Layer Thickness in Mice

Abstract

Purpose:The aim of this study was to introduce a new method to photograph the tear film lipid layer (LL) in mice and quantitatively measure lipid layer thickness (LLT).Methods:A total of 39 Bagg albino (BALB/c) mice (5-week-old) were used in this study. The system was composed of breadboard, light-emitting diode (LED) panel, right-angle mirror, dissection microscope, complementary metal oxide semiconductor camera, and computer. The white light emitted from the LED panel caused thin-film interference in the LL of the tear film, which reflected off the mirror and produced an image on the camera sensor. For the qualitative analysis, the mice were divided into 3 groups according to the LL interference patterns. LLT was quantified by analyzing the colors in the interference patterns.Results:Interference patterns were clearly observed in the lower half of the corneas. Based on quantitative analysis, the average LLT was 62.72 +/- 10.65 nm. When the interference pattern was qualitatively classified, 7 eyes were categorized into group 1 (thin), 19 eyes into group 2 (normal), and 3 eyes into group 3 (thick). The average LLT was 54.81 +/- 8.23 nm in group 1, 63.68 +/- 8.73 nm in group 2, and 75.11 +/- 15.48 nm in group 3, with a significant difference among the 3 groups (analysis of variance P = 0.012).Conclusions:We successfully photographed the interference pattern caused by the tear film LL in mice and quantitatively measured the LLT using an LED panel, mirror, dissection microscope, and camera.