Fig. 3

Representative OCT intensity profiles for the measurement of the tear film thickness. a A-scan of the precorneal tear film (PCTF). α, the anterior surface of the PCTF; β, the posterior surface of the PCTF; γ, the posterior surface of the cornea. b A-scan of the prelens tear film (PLTF). α, the anterior surface of the PLTF; β, the posterior surface of the PLTF or the anterior surface of the contact lens; γ, the posterior surface of the contact lens; ε, the posterior surface of the cornea. The thickness of tear film layer is calculated by determining the distance between peaks α and β