Correlation Analysis of Tear Film Lipid Layer Thickness and Ocular Surface Disease Index

ABSTRACT

PURPOSE: To analyze the relationship between ocular surface disease index and tear film lipid layer thickness (LLT) using a LipiView II® (LipiView® Ocular Surface Interferometer, TearScience®, Morrisville, NC, USA) interferometer. METHODS: Forty-nine patients diagnosed with dry eye syndrome were recruited for this prospective study. Patients completed ocular surface disease index questionnaires. We performed slit lamp examination, Schirmer test, corneal and conjunctival fluorescein staining, measured tear film break-up time, and graded meibomian gland dysfunction. Tear LLT, blinking time, and dynamic meibomian imaging were analyzed using a LipiView II® ocular interferometer. To control for missing data, we analyzed four sets of imputated data via the multiple imputation method and performed Pearson correlation analysis. Patients were assigned to one of two LLT categories (LLT < 60 or LLT ≥ 60) and Chi-square test was performed. RESULTS: Among ocular surface disease parameters, tear film break-up time (tBUT) had a statistically significant correlation with average and maximum LLT (average LLT; p = 0.008, 0.035, 0.006, 0.049, maximum LLT; p = 0.006, 0.042, 0.020, 0.049, Pearson correlation analysis with multiple imputation) but there was no significant correlation with minimum LLT (minimum LLT; p = 0.048, 0.090, 0.079, 0.039). Of the patients with a relatively thick average LLT or maximum LLT (LLT ≥ 60 nm), 80% and 88% had a tBUT < 10, respectively. Conversely, 39% and 47% of patients with relatively thin average LLT (LLT < 60 nm) had a tBUT < 10 (average LLT; p = 0.013, maximum LLT; p = 0.039). CONCLUSIONS: Average LLT and maximum LLT were significantly correlated with tBUT. Patients with a relatively thin average or maximum LLT tended to have a shorter tBUT. Based on these results, measuring tear film LLT using a LipiView II® interferometer may be useful in the diagnosis and follow-up of patients with evaporative dry eye.