TEAR FILM LIPID LAYER THICKNESS AS A FUNCTION OF BLINKING

Alterations in the tear film lipid layer as a function of blinking wer e investigated using a custom-designed specular reflection monitoring system. The tear film lipid layer of 104 subjects under conditions of normal (''baseline'') blinking and ''forceful'' blinking was quantitat ed on the basis of specific interference colors. Deliberate, forceful blinking was found to significantly increase the lipid layer thickness (LLT) of the tear film. The magnitude of increase was found to be cor related with the baseline LLT values; individuals with baseline LLT va lues of 75-150 nm demonstrated a mean increase in LLT of 33 nm followi ng forceful blinking, whereas subjects with baseline LLT values less-t han-or-equal-to 60 nm experienced a mean increase of 19 nm. The differ ence in the magnitude of increase between the groups was highly signif icant (p = 0.0001). The data suggest that, in addition to playing a ro le in the spreading of lipid across the tear film, the blinking mechan ism may be important in the maintenance of the lipid layer by augmenti ng the expression of lipids from the meibomian glands.