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Tomo Suzuki, Satoshi Fujiwara, Megumi Maekawa, Midori Nagase, Yorihiro Yamamoto, Shigeru Kinoshita; Fatty acid composition and lipid hydroperoxide in the meibum of patients with meibomian gland dysfunction. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4474.
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© ARVO (1962-2015); The Authors (2016-present)
Most meibomian lipids (meibum) are formed via the esterification of fatty acids (FAs), and the ratio of unsaturated/branched chain FAs in the lipids highly influences their melting temperature (Tm). We previously reported the composition of fatty acids in meibum of normal subjects; the composition being 40% saturated and 60% unsaturated fatty acids (ARVO 2013). However, the viscosity and Tm may change in meibum according to the severity of meibomian gland dysfunction (MGD). Thus, the purpose of this present study was to examine fatty acid composition and lipid hydroperoxide (HPO) in the meibum of MGD patients.
This study involved 7 MGD patients (age range: 34-73 years) and 10 normal control subjects (age range: 63-84 years). Meibum was obtained from the eyes of each subject by Daviel cataract spoon after gently squeezing the eyelid margin by use of a Yoshitomi meibomian gland compressor (T.M.I. Co. Ltd., Saitama, Japan) under a surgical microscope. Meibum was stored in chloroform/methanol and analyzed using gas chromatography mass spectrometry for composition analysis. HPO was analyzed by fluorescence intensity after reaction with a triphenylphosphine derivative.
In the meibum of the MGD patients, straight-chain saturated fatty acid (SFA) significantly increased (MGD: 4.7%, NL: 2.8%)(p<0.05), and branched-chain SFA (MGD: 35.6%, NL: 38.0%)(p<0.05) and poly-unsaturated fatty acids (PUFAs) (MGD: 3.2%, NL: 4.0%)(p<0.05) significantly decreased compared to that of the normal control subjects. HPO was found in the meibum obtained from the MGD patients, but not in that obtained from the normal control subjects. The HPO/free cholesterol ration was high in hypo-secretory MGD (1610±520) compared to in hyper-secretory MGD (10±11.1)(p<0.05).
FA composition in MGD patients showed a dramatic decrease of PUFAs and production of HPO. This may impact on the increase the viscosity of meibum resulting in tear film instability and the ocular surface damage.
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