Effects of Tear Film Lipid Layer Thickness and Blinking Pattern on Tear Film Instability After Corneal Refractive Surgery.

Abstract

To investigate associations between changes in tear film instability and the lipid layer thickness (LLT) and blink pattern after corneal refractive surgery (CRS). Forty patients were enrolled in this study. The LLT and blink pattern were evaluated 1 week before and 30 days after CRS using a novel interferometer and an ocular surface disease index (OSDI) questionnaire, and other tear film stability markers were also evaluated. Mean OSDI scores increased from 5.52 to 8.54 (P = 0.016), corneal fluorescence staining scores increased from 0.05 to 0.25 (P = 0.034), first noninvasive tear breakup time (NIBUT-F) decreased from 9.66 to 7.33 seconds (P = 0.014), and average noninvasive tear breakup time (NIBUT-Ave) decreased from 12.32 to 10.26 seconds (P = 0.047) 1 month after CRS. Meanwhile, mean total blink frequency in 20 seconds decreased significantly from 12.62 to 6.31 (P < 0.001); LLT did not change significantly (P = 0.447). The change in NIBUT-Ave was positively correlated with that in LLT (P = 0.003) and negatively correlated with that in the partial blink rate (P = 0.013). The changes in the OSDI questionnaire, NIBUT, LLT, and blink pattern were not different between the laser-assisted in situ keratomileusis and laser-assisted subepithelial keratomileusis groups. A decrease in tear film stability occurs 1 month after CRS, the change in the blink pattern and unchanged LLT preoperatively and postoperatively suggesting that these parameters play a role in maintaining tear film stability after CRS.