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K.K. Nichols, L. Young, K. Green–Church, C. Ziegler, J.J. Nichols; Assessment of Meibomian Lipids in Postmenopausal Women Using Electrospray Ionization Mass Spectrometry . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4446.
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Purpose:Electrospray ionization time–of–flight mass spectrometry (ESI–TOF) was used to characterize meibomian gland lipid from postmenopausal women with and without dry eye. Methods:Meibomian gland secretions were collected from 15 postmenopausal women using a sterile 1.5mm curette probe. The secretions were stored in a 2:1 chloroform/ methanol solution and frozen at –70° C until analysis. Meibomian gland secretions were directly infused at 20 µL/min to a Micromass LCT equipped with an orthogonal electrospray source (Z–spray) which was operated in positive ion mode. Clinical tests performed (right eye) included: symptom and history surveys, osmolarity, non–invasive and fluorescein tear break–up, meibomian gland evaluation, infrared meibography, fluorescein corneal staining, lissamine green conjunctival staining, and the phenol red thread test. Results:Of the sample, 26.7% (4/15) reported a previous dry eye diagnosis, although 46.7% (7/15) use artificial tears on a routine basis. Average osmolarity was 312.4 ± 28.9 mOsm, average fluorescein tear break–up time was 7.3 ± 2.4 sec., average thread wetting was 24.5 ± 5.9 mm/15 seconds, 40.0% demonstrated any corneal staining, and 73.3% showed mild (1–25%) meibomian gland drop–out on meibography. No statistically significant differences were found in mentioned clinical test results between patients reporting/not reporting a previous dry eye diagnosis. The most prominent peaks observed in the lipid profiles are as follows: 304.2, 489.2, 585.5, 770.5, and 955.6. A peak at 727.5 (thought to be sphingomyelin) was absent in the majority of profiles. The peak at 304.2 has been identified as oleamide + sodium. Conclusions: It remains a challenge to classify patients as "dry eye" on the basis of symptoms and clinical test results or even a previous "dry eye diagnosis." Comparison of lipid profiles and assessment of peak strength (quantification) may yield further information particularly with the presence or absence of specific molecular weight peaks.
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