Meibum Color and Free Fatty Acid Composition in Patients With Meibomian Gland Dysfunction.

PURPOSE We measured the components of meibum in patients with meibomian gland dysfunction (MGD) and control subjects and then examined the relation between meibum composition and clinical parameters. METHODS Thirty-eight patients with MGD (13 men and 25 women; mean age ± SD, 66.9 ± 15.0 years) and 20 control subjects (8 men and 12 women; 64.5 ± 6.7 years) were enrolled. Ocular symptom score, keratoconjunctival staining score, tear film breakup time, and Schirmer's test value were determined. Lid margin abnormalities and meibomian gland morphology were assessed for upper and lower eyelids, and meibum properties were evaluated at temporal, central, and nasal sites of each lid. Free fatty acid (FFA) composition of meibum was analyzed by liquid chromatography-Fourier transform mass spectrometry. RESULTS Upper meibum color score was significantly correlated with epiphora and sticky sensation in MGD patients. Meibum grade, color, or viscosity did not differ significantly among the sites evaluated. A total of 103 species of FFA--including very long chain (such as C36 and C37) and odd-numbered chain (such as C17, C19, and C21) FFAs--were detected in meibum. Free fatty acid composition differed between clear and colored (cloudy or yellow) meibum, with unsaturated FFAs tending to be more abundant in colored meibum. CONCLUSIONS Free fatty acid composition of human meibum correlates with meibum color as determined with a slit-lamp microscope. This finding may provide insight into the pathogenesis of MGD.