Characteristics of dry eye patients with thick tear film lipid layers evaluated by a LipiView II interferometer

Purpose To investigate the characteristics of eyes with dry eye disease (DED) whose lipid layer thickness (LLT) measured 100 nm on a LipiView II interferometer and compare the DED parameters of them to those with LLT below 100 nm. Methods A total of 201 eyes of 102 enrolled DED patients (mean age 56.4 ± 11.8 years) were classified into 3 groups according to their average LLT; < 60 nm as thin-LLT ( n = 49), 60–99 nm as normal-LLT ( n = 77), and 100 nm as thick-LLT ( n = 75). LLT, meiboscore, Schirmer I test, tear film break-up time (TBUT), ocular surface staining (OSS), and ocular surface disease index (OSDI) were assessed. Results The OSS and TBUT were significantly worse in the thick-LLT group than in the normal-LLT group ( p = 0.020, and p = 0.028, respectively). The OSDI was significantly higher in the thick-LLT group than in the thin-LLT group ( p = 0.006). However, the meiboscore was not different among the three groups ( p = 0.33). Age, OSS, and OSDI showed a positive correlation with LLT ( r = 0.16, p = 0.023; r = 0.213, p = 0.003; and r = 0.338, p = 0.001, respectively). In sensitivity analyses, eyes with corneal erosions had a significantly higher average LLT ( p = 0.015), higher OSDI ( p = 0.009), shorter TBUT ( p < 0.001), and shorter Schirmer I value ( p = 0.024) than those with clear corneas. Conclusion The average LLT of eyes with corneal erosions was thicker than those without erosions, suggesting that the LLT of 100 nm in the eyes with corneal erosions should not be regarded as a stable physiologic condition. Cautious interpretation of LLT along with other dry eye parameters is required.