Statistical analysis
All statistical analyses were performed using SPSS Statistics version 22.0 (IBM Corp., Armonk, NY, USA). All data are presented as the mean ± standard. The chi-square test was used to compare sex and age among the four groups. The means of the parameters (OSDI scores, TMH, NIKBUT, FL, lid margin abnormality, MG dropout, meibum quality, and SIT) were compared among the groups with one-way ANOVA or Welch ANOVA according to the homogeneity of variance. The Spearman correlation test was used to calculate correlations. All 