The purpose of this study was to structurally characterize the major lipid species present in human meibomian gland secretions (MGS) of individual subjects by means of ion trap atmospheric pressure ionization mass spectrometry analysis (API MS n ). The samples of MGS and authentic lipid standards were analyzed in direct infusion and high-pressure liquid chromatography (HPLC) experiments with API MS n detection of the analytes (HPLC API MS n ). The major precursor ions were isolated and subjected to further sequential fragmentation in MS n experiments, and their fragmentation patterns were compared with those of authentic lipid standards. Multiple precursor ions were observed in the positive-ion mode. Among those, previously identified cholesterol (Chl; m/z 369; [M 2 H 2 O 1 H] 1 ) and oleic acid (OA; m/z 283; [M 1 H] 1 ) were found. The other major compounds of the general molecular formula C n H 2n-2 O 2 were consistent with wax esters (WEs), with OA as fatty acyl component. Accompanying them were two homologous series of compounds that fit the molecular formulas C n H 2n-4 O 2 and C n H 2n O 2 . Subset 2 was found to be a homolog series of linoleic acid-based WEs, whereas subset 3 was, apparently, a mixture of stearic acidbased WEs. HPLC API MS n analysis revealed the presence of large quantities of cholesteryl esters (Chl-Es) in all of the tested samples. Less than 0.1% (w/w) of oleamide was detected in human MGS. In the negative-ion mode, three major compounds with m/z values of 729, 757, and 785 that were apparently related to anionogenic lipids of the diacylglyceryl family were found in all of the samples. Common phospholipids and ceramides (Cers) were not present among the major MGS lipids. Phosphocholine-based lipids were found in MGS in quantities less than 0.01% (w/w), if at all. This ratio is two orders of magnitude lower than reported previously. These observations suggest that MGS are a major source of nonpolar lipids of the WE and Chl-E families for the tear film lipid layer, but not of its previously reported (phospho)lipid, Cer, and fatty acid amide components.-Butovich, I. A., E. Uchiyama, and J. P. McCulley. Lipids of human meibum: mass-spectrometric analysis and structural elucidation. J. Lipid Res.

The purpose of the study was to qualitatively characterize the major lipid species present in human meibomian gland secretions (MGS) by means of high-performance liquid chromatography with atmospheric pressure ionization mass spectrometric detection of the analytes (NP HPLC-MS). Two different NP HPLC-MS methods have been developed to analyze lipid species that were expected to be present in MGS. The first method was optimized for the analysis of relatively nonpolar lipids [wax esters (WE), di- and triacyl glycerols (DAG and TAG), cholesterol (Chl) and its esters (Chl-E), and ceramides (Cer)], while the second method was designed to separate and detect phospholipids. The major lipid species in MGS were found to be WE, Chl-E, and TAG. A minor amount of free Chl (less then 0.5% of the Chl-E fraction) was detected in MGS. No appreciable amounts of DAG and Cer were found in MGS. The second NP HPLC-MS method, capable of analyzing model mixtures of authentic phospholipids (e.g. phosphatidylglycerol, phosphatidylethanolamine, phosphatidic acid, phosphatidylinositol, phosphatidylserine, phosphatidylcholine, and sphingomyelin) in submicrogram/mL concentrations, showed little or no presence of these species in the MGS samples. These observations suggest that MGS are a major source of the nonpolar lipids of the WE and Chl-E families for the tear film lipid layer (TFLL), but not of the previously reported phospholipid components of the TFLL.

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Dietary supplementation with omega-3 fatty acids in dry eye showed no significant effect in meibum lipid composition or aqueous tear evaporation rate. On the other hand, the average tear production and tear volume was increased in the omega-3 group as indicated by both Schirmer testing and fluorophotometry.

These studies quantitatively show the negative impact of environmental low relative humidity conditions, including those associated with commercial airplane travel, on aqueous tear evaporation dynamics. The increased evaporative rate is similar in healthy subjects and patients with dry eye. These findings provide useful data for the development and evaluation of treatment paradigms for any person who notes dry eye symptoms in low relative humidity environments.

PurposeTo assess the extended efficacy and safety of suprachoroidal triamcinolone acetonide injectable suspension (CLS-TA) among patients with macular oedema (ME) secondary to non-infectious uveitis (NIU).MethodsPatients with uveitic ME were treated with suprachoroidal CLS-TA at baseline and week 12 of the Efficacy and Safety of Suprachoroidal CLS-TA for Macular Edema Secondary to Noninfectious Uveitis: Phase 3 Randomized Trial (PEACHTREE) study. Time to rescue was evaluated over 24 additional weeks for MAGNOLIA. Safety data, visual acuity and retinal central subfield thickness (CST) reduction were also evaluated. Of the 53 eligible patients (46 CLS-TA and 7 control), 33 patients were enrolled (28 CLS-TA and 5 control).ResultsOver the entire 48-week period for PEACHTREE and MAGNOLIA, the median time to rescue therapy was 257 days versus 55.5 days for the CLS-TA and sham-control arms, respectively. Of 28 CLS-TA treated patients who participated in MAGNOLIA, 14 (50%) did not require rescue therapy through approximately 9 months after the second treatment. Among CLS-TA patients not requiring rescue, there was a mean gain of 12.1 letters and mean CST reduction of 174.5 µm at week 48. No serious adverse events related to study treatment were observed.ConclusionApproximately 50% of patients did not require additional treatment for up to 9 months following the last CLS-TA administration.

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PURPOSE. We evaluated quantitatively direct effects of ceramide (Cer) and free cholesterol (FC) on meibomian lipid films (MLF) using a Langmuir trough (LT) and a Brewster angle microscope (BAM). METHODS. Meibum was obtained from healthy volunteers. A series of mixtures of meibum with Cer or FC (mixed MLF)taken in different ratios were tested. Standard rheologic parameters, such as elasticity and hysteresis of MLF, were computed. BAM was used to study the morphology of MLF.RESULTS. Pure MLF were capable of withstanding multiple compression-expansion cycles with little hysteresis observed (~1.9 J/g meibum). The films made of either pure Cer or pure FC were clearly collapsible, and had much higher rigidity and hysteresis than pure meibum. Adding progressively higher amounts of Cer or FC to meibum had a strong impact on the rigidity, stability, and morphology of the mixed MLF: their hysteresis increased many fold compared to pure meibum. A concomitant increase in the rigidity and collapsibility of the mixed MLF was observed.CONCLUSIONS. Cer and FC changed the surface properties of mixed MLF in a way that implied their destabilization and/or disruption. One of the mechanisms that might lead to these effects is strong aggregation of meibum lipids with FC or Cer that leads to the formation of smaller particles of meibum surrounded by a thinner layer of FC or Cer. As Cer and FC can be elevated in meibum and the tear film because of certain pathologic processes, or can be of exogenous nature, our results can explain (partially) a less stable tear film in those subjects. (Invest Ophthalmol Vis Sci. 2013;54:1352-1360) DOI:10.1167/iovs.12-10662 T he preocular tear film (TF) is a complex aqueous structure that is enriched with lipids, proteins, carbohydrates and other molecules of biological origin. TF covers the entire ocular surface.1 The outermost layer of the tear film, also called tear film lipid layer (TFLL), is formed predominantly from a mixture of lipids called ''meibum.'' Meibum is produced by holocrine lipid-secreting meibomian glands (MG), which are located in the tarsal plates of the eyelids. [2][3][4] This outer layer is believed to prevent the evaporation of the TF, lubricate the ocular surface, and avert the invasion of pathogenic microorganisms. 5 Reportedly, adverse changes in the lipid composition of meibum 6-12 could impact negatively the integrity and stability of the TF, compromising the health of the ocular surface, and predisposing it to the development of various ocular pathologies. One of the latter, the dry eye disease (DED), is one of the most prevalent ocular diseases. One of the forms of DED is known commonly as meibomian gland dysfunction (MGD), 13 while another common condition that is associated with meibum and TFLL abnormalities is chronic posterior blepharitis (CPB). 14 Comprehensive chemical analyses of normal (i.e., non-dry eye) meibum samples collected from healthy subjects have demonstrated a very complex nature of meibomian lipids. Many lipid classes were shown to be present in normal ...