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Louis Tong, Sin Man Lam, Guanghou Shui, Hwee Kuan Lee, Jen Hong Tan, Rajendra Acharya, Markus Wenk; Longitudinal changes of tear lipids with lid warming treatment in meibomian gland dysfunction. Invest. Ophthalmol. Vis. Sci. 2014;55(13):34.
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© ARVO (1962-2015); The Authors (2016-present)
Eyelid warming is currently the major treatment strategy used in MGD, a major health condition. We have recently conducted a randomized controlled treatment (RCT) trial of lid warming devices in MGD, and evaluated longitudinal changes of lipids in the meibum of these patients.
32 patients, mean age 54.7 years (SD:10.4) and 65.6% females, were analysed. 53.1% had some aqueous deficiency (Schirmers I <= 8 mm/5 minutes), whereas 75% had tear instability (break up time <3 sec). 10 patients had hot towel compress, 10 had Eyegiene and 12 had Blephasteam. Tear lipids collected at baseline and 12 weeks were analysed. The relative levels of lipid species were obtained using mass spectrometry as previously described. Non-invasive infrared meibography was used to assess MG loss and tear evaporation rates measured by thermography.
Treatment-induced change (p<0.001) among 550 lipids/classes was observed for 30 lipids (7 increased and 23 reduced). Most lipids increased are O-acyl hydroxyl ω fatty acids (OAHFAs). The greatest percentage decrease (70%) was noted for lysophosphotydl inositol (LPI)18:0 whereas the greatest increase (93%) was noted for phosphatidyl ethanolamine (PE)36:2. Only 2 of the 30 lipids that changed were correlated to a reduction in dry eye symptoms. (OAHFA 18:1/32:2, r=-0.371, p=0.036 and OAHFA 18:1/33:1, r=-0.355, p=0.046). When meibography images were graded into healthy, intermediate and unhealthy, only LPI20:4 level after treatment was associated with initial meibography grading (p=0.028). The LPI20:4 level was greatest in the unhealthy group, and significantly greater than in the healthy group on post hoc tests (p=0.03). The drop in 3 lipids LPC18:2 (r=0.38) , LPE18:0p (r=0.41) and LPE20:1p (r=0.36) was associated with the decrease in tear evaporation. The lipids increased with treatment OAHFA 18:1/30:1 (r=-0.43) and OAHFA 18:1/31.0 (r=-0.38) were also associated with the reduction in tear evaporation. The change in the OAHFA class was inversely correlated to the change in the evaporative rate (r=-0.39) and the change in LpPE was directly correlated to the change in evaporative rate (r=0.41).
The lipids deficient in dry eye such as OAHFAs are increased by lid warming treatment. The change in 2 lipids correlates to the extent of symptomatic improvement. Lipid changes correlate to the change in tear evaporation, suggesting a functional role of lipids in MGD.
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