**3.6 Tear film lipid layer (TFLL) quality by TFLL interferometry**

Noninvasive TFLL quality assessment was performed with DR-1 (Kowa, Nagoya, Japan). Yokoi DE severity grading system was performed. Grade 1: somewhat gray color, uniform distribution; grade 2: rather gray color, nonuniform distribution; grade 3: a few colors, nonuniform distribution; grade 4: many colors, nonuniform distribution; and grade 5: corneal surface partially. 24 of refractive, refractive.
