Tear Film Lipid Layer Research Articles

Effects of Lipiflow Treatment Prior to Cataract Surgery: A Prospective, Randomized, Controlled Study

Prospective, randomized controlled study. This study comprised 124 eyes of 124 patients with planned surgery for senile cataract. Participants were randomly allocated into control and Lipiflow groups based on administration of Lipiflow treatment 3 weeks before cataract surgery. For meibomian gland (MG) evaluation, MG atrophy, degree of gland expressibility, and quality of gland secretions were examined at the baseline visit and 1 and 3 months postoperatively. Ocular surface parameters of tear film break-up time, Oxford corneal staining score, and tear film lipid layer thickness were measured at each visit. Ocular Surface Disease Index and Dry Eye Questionnaire were also assessed. The control group exhibited a significant decrease in MG expressibility, worsened meibum quality, decreased lipid layer thickness, and worsened corneal staining after cataract surgery. Also, dry eye symptom showed significant worsening. Conversely, the Lipiflow group showed significantly improved MG patency and meibum quality, increased tear film break-up time, and reduced corneal staining, and presented improved subjective outcomes reported on both Ocular Surface Disease Index and Dry Eye Questionnaire. The improvement of each parameter in the Lipiflow group showed a linear correlation with baseline MGD grade. In addition, patients without baseline MGD showed less worsening or improvement of MGD and dry eye induced by surgery, with preoperative Lipiflow treatment. Preoperative Lipiflow treatment conducted before cataract surgery may be a safe and effective intervention for relieving MGD and dry eye induced by surgery. It might be recommended not only for the patients with preoperative MGD but also for those without baseline MGD, to prevent the development of MGD and dry eye induced by ocular surgeries.

Treatment of contact lens related dry eye with intense pulsed light

AimThe prevalence of contact lens related dry eye (CLDE) is high and can lead to ocular discomfort, reduced quality of vision and life. The aim of this study was to assess the efficacy of intense pulsed light (IPL) treatment in alleviating signs and symptoms of CLDE. DesignProspective, randomised, examiner masked study. MethodsThis prospective study was conducted on 152 eyes of 76 patients (IPL group, n = 76 eyes; control group, n = 76 eyes) wearing contact lens (CL) and experiencing CLDE for more than 1 year. The IPL treatment group underwent two IPL treatment sessions at 3-week intervals while the control group received sham IPL treatment. Best-corrected visual acuity (BCVA), ocular surface disease index (OSDI), non-invasive breakup time (NITBUT), tear film lipid layer (TFLL) quality, fluorescein staining (FS), meibum gland (MG) quality and expression, endothelial cell count (ECC) and intraocular pressure (IOP) were assessed at baseline (D-0), day-21 (D-21) and day-42 (D-42) after IPL treatment. ResultsThe mean age of treatment group and control group was 28.47 ± 5.16 years (21 females, 28 %) and 28.58 ± 4.33 years (23 females, 30 %) respectively. IPL treatment group had clinically and statistically significant improvement in mean NITBUT was observed at D14 (5.24 s, P<0.001) and D28 (6.08 s, P<0.001). OSDI, TFLL score and MG quality and expressibility all improved significantly (P<0.001) at D-42, whereas BCVA, ECC and IOP showed no significant changes at D-21 and D-42 in IPL treatment group. The control group showed no significant improvement in all parameters at D-21 and D-42. ConclusionOur findings suggest that CL related DE can be safely alleviated with IPL treatment as it reduced the severity of symptoms, improved the overall tear film stability and reduced artificial tear use in participants with CLDE.

Relationship between the partial blink rate and ocular surface parameters.

PurposeTo elucidate the relationship between partial blink rate (PBR) and ocular surface parameters.MethodsWe conducted a retrospective cross‐sectional study of the patients who visited the Kim’s Eye Hospital between March 2020 and July 2020. Blinking dynamics, tear film lipid layer thickness (LLT), non-invasive tear film break- up time (NITBUT), tear meniscus height (TMH), and meibomian gland (MG) dropout rate were assessed using the IDRA® Ocular surface analyzer (SBM SISTEMI, Inc., Torino, Italy) (IDRA). Dry eye symptoms were quantified by the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire scores.ResultsA total of 47 non-Sjögren dry eye patients (47 right eyes, mean age = 56.8 ± 14.5 [20–75] years, 66% female) were enrolled. Among the ocular surface parameters, PBR had strong correlations with MG dropout rate (r = 0.811; p < 0.01) and moderate correlations with SPEED scores (r = 0.596; p < 0.01). MG dropout rate and age had moderate correlations with SPEED scores (r = 0.416; p = 0.04 and r = 0.322; p = 0.03, respectively). Comparisons by sex revealed no significant difference in characteristics, except for the TMH value. The TMH of female patients (0.17 ± 0.07) was significantly higher than that of males (0.14 ± 0.04; p = 0.04). LLT showed no significant correlation with the other variables.ConclusionPBR and MG dropout rates measured with IDRA were significantly correlated to dry eye symptoms.

Categorization of Marketed Artificial Tear Formulations Based on Their Ingredients: A Rational Approach for Their Use.

Dry eye disease is a common ocular condition affecting millions of people worldwide. Artificial tears are the first line therapy for the management of dry eye disease. Artificial tear formulations contain a variety of active ingredients, biologically active excipients, and preservatives. Many of these formulations are also available as preservative-free. This study was conducted to inspect artificial tear formulations currently marketed in the United States for their active ingredients, biologically relevant excipients, and preservatives. The marketed artificial tears were examined at various US retail pharmacy chains and using the manufacturers’ website to compile information about active ingredients, inactive ingredients, and preservatives. The currently marketed artificial tears can be grouped into four categories based on their active ingredients. The artificial tears also contain biologically active chemicals listed as inactive ingredients, which have osmoprotectant, humectant, and tear film lipid layer or mucous layer mimicking properties. Most artificial tears contain vanishing type preservatives such as purite or sodium perborate and safer quaternary compound polyquaternium-1. The majority of these artificial tear formulations are also available as preservative-free single dose unit. The study provides a formulary of artificial tears based on active ingredients, biologically active excipients, and the preservative-free option. The formulary should assist healthcare providers in making a stepwise and rational selection of appropriate artificial tears for patients suffering from dry eye disease.

The Properties and Role of O-Acyl-ω-hydroxy Fatty Acids and Type I-St and Type II Diesters in the Tear Film Lipid Layer Revealed by a Combined Chemistry and Biophysics Approach.

The tear film lipid layer (TFLL) that covers the ocular surface contains several unique lipid classes, including O-acyl-ω-hydroxy fatty acids, type I-St diesters, and type II diesters. While the TFLL represents a unique biological barrier that plays a central role in stabilizing the entire tear film, little is known about the properties and roles of individual lipid species. This is because their isolation from tear samples in sufficient quantities is a tedious task. To provide access to these species in their pure form, and to shed light on their properties, we here report a general strategy for the synthesis and structural characterization of these lipid classes. In addition, we study the organization and behavior of the lipids at the air–tear interface. Through these studies, new insights on the relationship between structural features, such as number of double bonds and the chain length, and film properties, such as spreading and evaporation resistance, were uncovered.

Interactions of Meibum and Tears with Mucomimetic Polymers: A Hint towards the Interplay between the Layers of the Tear Film.

Recent clinical findings suggest that mucomimetic polymers (MMP) can alter not only the texture of the aqueous tear but also the spreading and structure of the tear film (TF) lipid layer, thereby allowing for their synchronized performance in vivo. Thus, we aimed to evaluate in vitro (i) the capability of pharmaceutically applicable MMP to ensure the formation of post-evaporative ferning patterns (a characteristic feature of the “healthy” tear colloid) and (ii) the MMP interactions with human meibum films accessed in the course of blink-like deformations via Langmuir surface balance and Brewster angle microscopy (BAM). Four MMP were used- hyaluronic acid (HA), cross-linked hyaluronic acid (CHA), carboxymethyl cellulose (CMC) and gellan gum (GG)- at the concentrations of 0.0001%, 0.001%, 0.01%, 0.05% and 0.1%. Significant differences were observed in the MMP fern formation capability: CHA (≥0.001%) > HA (≥0.01%) = CMC (≥0.01%) > GG (≥0.05%). All MMP affected the spreading of meibum, with BAM micrographs revealing thickening of the films. CHA was particularly efficient, showing concentration-dependent enhancement of tear ferning and of meibomian layer structure, surfactant properties and viscoelasticity. Thus, endogenous and exogenous MMP may play key roles for the concerted action of the TF layers at the ocular surface, revealing novel routes for TF-oriented therapeutic applications.

The cover photo shows different neovascularization types from the paper by Smid et al.

The cover photo shows different neovascularization types from the paper by Smid et al.

Effect of Intense Pulsed Light on Anterior Corneal Aberrations and Quality of Vision in Patients with Evaporative Dry Eye.

Objective: To evaluate the improvement in the tear film lipid layer (TFLL) and its subsequent impact upon corneal aberrations following intense pulsed light (IPL) treatment in patients with evaporative dry eye disease (DED) due to meibomian gland dysfunction (MGD). Background: The prevalence of DED is common and can lead to ocular discomfort, reduced visual acuity, and lowered quality of vision (QoV) and life. Methods: In this self-control study, patients with moderate-to-severe evaporative DED due to MGD were consecutively enrolled and underwent two IPL treatments at 3-week intervals. Clinical assessments, such as Ocular Surface Disease Index (OSDI) and QoV questionnaires, anterior corneal aberrations, noninvasive tear breakup time (NITBUT), interferometric fringe pattern as determined by TFLL quality, corneal fluorescein staining (CFS), meibum gland (MG), conjunctival hyperemia (CH), best-corrected visual acuity, endothelial cell count, and intraocular pressure, were conducted at pretreatment (D-0), day 21 (D-21), and day 42 (D-42) after IPL treatment. Results: The final analysis included 124 eyes of 62 patients (29 females, 33 males; mean age 35.66 ± 11.09 years). Clinically and statistically significant improvement in NITBUT was observed at D-42 (p < 0.01). OSDI, QoV, TFLL score, and MG quality and expressibility all improved significantly (p < 0.05) at D-42, whereas CH (p = 0.073) and CFS (p = 0.058) showed minor not significant improvements at D-42 of assessment. Anterior corneal aberrations also improved significantly at D-42 of assessment (p < 0.05). Conclusions: IPL treatment reduced the severity of symptoms and improved the overall tear film (TF) stability in patients with moderate-to-severe evaporative dry eye (DE) due to MGD. Additionally, the significant improvement in QoV in DE patients can be attributed to the reduction in anterior corneal aberrations due to improved TF stability.

Clinical Implication of Patchy Pattern Corneal Staining in Dry Eye Disease.

Corneal fluorescein staining in a form that is commonly called a “patchy pattern (PP)” is sometimes seen with or without superficial punctate keratopathy (SPK) in dry-eye diseases (DEDs). Here, we investigated the differences in the clinical features of DED patients with and without PP corneal staining (PPCS). This study involved 35 DEDs with PPCS (PPCS group) and 30 DEDs with SPK and without PPCS (non-PPCS group). The tear meniscus radius (TMR, mm), spread grade (SG) of the tear-film lipid layer (i.e., SG 1–5, 1 being best), noninvasive breakup time (NIBUT, seconds), fluorescein breakup time (FBUT, seconds), corneal epithelial damage (CED, 15 points maximum), conjunctival epithelial damage (CjED, six points maximum), the Schirmer’s 1 test (ST1, mm), and the prevalence of Sjögren’s syndrome (SS) were examined, and then compared between the two groups. Our findings revealed that between the groups (PPCS vs. non-PPCS), there was a statistically significant difference (p < 0.05) in CjED (3.1 ± 1.9 vs. 1.3 ± 1.6), ST1 (5.6 ± 7.4 vs. 14.8 ± 11.4), and the prevalence of SS (60.0% vs. 16.7%). Our findings suggest that DEDs and dry-eye patients with PPCS may indicate not only SS itself, but also the ophthalmological characteristics compatible with SS.

Barriers in the Eye and Lungs that Maintain Biological Functions

People's lives depend to a large extent on biological barriers that line, e.g., the surfaces of our lungs and eyes. These barriers regulate molecular transfer and protect the body from external threats. In this work, we discuss how biological barriers function on the surfaces of the eye and the lungs. Regarding eye function, the dry eye syndrome affects about one-third of the world's population. It is typically caused by excessive evaporation of aqueous tear fluid from the ocular surface, and the key reason for excessive evaporation is impaired function of the tear film lipid layer (TFLL), whose function is to cover the aqueous tear film and resist evaporation.

Characteristics of dry eye patients with thick tear film lipid layers evaluated by a LipiView II interferometer

PurposeTo investigate the characteristics of eyes with dry eye disease (DED) whose lipid layer thickness (LLT) measured 100 nm on a LipiView II interferometer and compare the DED parameters of them to those with LLT below 100 nm.MethodsA total of 201 eyes of 102 enrolled DED patients (mean age 56.4 ± 11.8 years) were classified into 3 groups according to their average LLT; < 60 nm as thin-LLT (n = 49), 60–99 nm as normal-LLT (n = 77), and 100 nm as thick-LLT (n = 75). LLT, meiboscore, Schirmer I test, tear film break-up time (TBUT), ocular surface staining (OSS), and ocular surface disease index (OSDI) were assessed.ResultsThe OSS and TBUT were significantly worse in the thick-LLT group than in the normal-LLT group (p = 0.020, and p = 0.028, respectively). The OSDI was significantly higher in the thick-LLT group than in the thin-LLT group (p = 0.006). However, the meiboscore was not different among the three groups (p = 0.33). Age, OSS, and OSDI showed a positive correlation with LLT (r = 0.16, p = 0.023; r = 0.213, p = 0.003; and r = 0.338, p = 0.001, respectively). In sensitivity analyses, eyes with corneal erosions had a significantly higher average LLT (p = 0.015), higher OSDI (p = 0.009), shorter TBUT (p < 0.001), and shorter Schirmer I value (p = 0.024) than those with clear corneas.ConclusionThe average LLT of eyes with corneal erosions was thicker than those without erosions, suggesting that the LLT of 100 nm in the eyes with corneal erosions should not be regarded as a stable physiologic condition. Cautious interpretation of LLT along with other dry eye parameters is required.

Efficacité de la lumière pulsée dans le traitement des sécheresses oculaires sévères par dysfonctionnement meibomien

Dry eye syndrome caused by Meibomian gland dysfunction (MGD) is a common disease in the general population and impairs quality of life. Intense Pulsed Light (IPL) has mainly been used in dermatology for the treatment of skin disorders, and more recently for MGD-related dry eye. The objective of our study is to evaluate the efficacy and tolerability of IPL with the E-Eye® device (E-Swin, Houdan, France) in severe MGD-related dry eye patients. This non-comparative study included 20 patients with MGD-related dry eye with a Break-Up Time (BUT)<10seconds, dry eye symptoms >30mm on a Visual Analog Scale (VAS), and failure of lid hygiene and artificial tears. Treatment consisted of 3 sessions of IPL on D0, D15, and D45 (5 flashes of 13J/cm2 per eye). The following parameters were assessed at each visit and at D75: symptoms graded with a VAS and the Standard Patient Assessment of Eye Dryness questionnaire (SPEED), BUT, corneal fluorescein staining, Meibomian gland expression score, meibography, tear film lipid layer thickness by interferometry and the ocular scattering index by double-pass aberrometry (OQAS). Statistical analysis was performed on the eye most affected at baseline. We included 40 eyes of 20 patients, 15 female and 5 male, mean age 47±15 years (24 to 74 years). The symptoms rated by VAS were severe, averaging 69±25mm. After treatment, there was a statistically significant decrease in symptoms, with a 14mm VAS decrease (55±29mm at D75 versus 69mm at D0, P=0.048) and SPEED score of 3.4 (19.0±6mm versus 22.4±4.6, P=0.03). The number of expressible Meibomian gland ducts increased significantly (from 5.9 to 8.1, P=0.04), lid redness decreased (from 1.4 to 0.6, P=NS) and BUT improved (from 4.2 to 5.9, P=NS). Other parameters remained unchanged. Three patients (15%) complained of transient ocular burning after each treatment. IPL appears to be effective in improving signs and symptoms in patients with severe MGD-related dry eye, with a good safety profile. Its exact mechanism of action remains to be elucidated.

A Blink-Assisted, Cornea-Sparing Wearable Eyelid Device for the EffectivePenetration of Therapeutic Thermal Energy into the Meibomian Glandsfor the Treatment of Dry Eye Disease

Meibomian Gland Dysfunction (MGD) is the leading cause of Dry Eye Disease (DED). In MGD, obstructed meibomian glands result in reduced meibum secretion and a compromised tear lipid layer that causes tear film instability and an accelerated evaporation of tears. This accelerated and excessive tear evaporation in turn leads to the signs and symptoms of DED. Research has demonstrated that an elevated and sustained therapeutic temperature of at least 41°C at the tarsal conjunctiva located at inner surface of the eyelid can liquefy hardened or thickened meibum and help clear gland obstructions in MGD. By clearing the obstructions, restored meibomian glands can resume the production of meibum that can flow naturally out of the glands and onto the tear surface thereby restoring a stable and healthy tear film lipid layer. Fortifying the lipid layer by enhancing natural meibum production is an effective treatment for evaporative dry eye disease. In recent years, several devices have been developed that utilize thermal energy to treat DED and MGD that require heating from inside the eyelids. The medical community has debated the ability to achieve therapeutic level of temperatures at the tarsal conjunctiva via a non-invasive external approach. This article discusses a new device, TearCare, that has achieved and maintained the requisite 41°C therapeutically-effective, meibum-melting temperature at the tarsal conjunctiva non-invasively through a combination of novel features including: wearability, total tarsal conformance, blink assistance, and software sensor-controlled thermal maximization and optimization.

Improving Stability of Tear Film Lipid Layer via Concerted Action of Two Drug Molecules: A Biophysical View.

The tear film at the ocular surface is covered by a thin layer of lipids. This oily phase stabilizes the film by decreasing its surface tension and improving its viscoelastic properties. Clinically, destabilization and rupture of the tear film are related to dry eye disease and are accompanied by changes in the quality and quantity of tear film lipids. In dry eye, eye drops containing oil-in-water emulsions are used for the supplementation of lipids and surface-active components to the tear film. We explore in detail the biophysical aspects of interactions of specific surface-active compounds, cetalkonium chloride and poloxamer 188, which are present in oil-in-water emulsions, with tear lipids. The aim is to better understand the macroscopically observed eye drops–tear film interactions by rationalizing them at the molecular level. To this end, we employ a multi-scale approach combining experiments on human meibomian lipid extracts, measurements using synthetic lipid films, and in silico molecular dynamics simulations. By combining these methods, we demonstrate that the studied compounds specifically interact with the tear lipid film enhancing its structure, surfactant properties, and elasticity. The observed effects are cooperative and can be further modulated by material packing at the tear–air interface.

Intense Pulse Light for Treating Post-LASIK Refractory Dry Eye.

Objective: Optimal pulse technology-intense pulse light (OPT-IPL) treatment on patients with post-LASIK refractory dry eye (DE). Background: The prevalence of dry eye disease is common and can lead to ocular discomfort, reduced visual acuity, lowered quality of vision and life. Materials and methods: A prospective study was conducted on 72 eyes of 36 patients (treatment group, n = 42 eyes; control group, n = 30 eyes) who had previously undergone myopic LASIK correction with subsequent refractory DE. All eyes fulfilled the Japanese DE criteria and had not responded to conventional DE treatment. The treatment group underwent two OPT-IPL treatment sessions at 2-week intervals, while the control group received no treatment. Best-corrected visual acuity (BCVA), ocular surface disease index (OSDI), noninvasive breakup time (NITBUT), tear film lipid layer (TFLL) quality, corneal fluorescein staining, meibum gland (MG), endothelial cell count (ECC), and intraocular pressure (IOP) were assessed at baseline (D0), day-14 (D14) and day-28 (D28) after OPT-IPL treatment. Results: The mean age of treatment group and control group was 30.48 ± 5.16 years (12 females, 57%) and 31.00 ± 4.33 years (8 females, 53%), respectively. Treatment group had clinically and statistically significant improvement in NITBUT and was observed at D14 (p < 0.001) and D28 (p < 0.001). OSDI, TFLL score, and MG quality and expressibility improved significantly (p < 0.05) at D28, whereas BCVA, ECC, and IOP showed no significant changes at D14 and D28 between the groups. Conclusions: Our results suggest that post-LASIK refractory DE is safely treated with OPT-IPL treatment. OPT-IPL treatment reduced the severity of symptoms and improved the overall tear film stability in patients with severe refractory DE post-LASIK surgery. In addition, the frequency of artificial tears usage was significantly less and can be attributed to the reduction in OSDI scores due to improved TFLL and tear film stability.

Characteristics of tear film lipid layer in young dry eye patients

To investigate the characteristics of subjective symptoms and objective parameters among young patients with dry eye disease (DED) and compare them with those of older patients. We retrospectively enrolled 675 patients with DED who were divided into three age groups (20-41 years [younger], 41-60 years [middle], and >60 years [older]) (n=143, 304, and 228, respectively). Subjective symptoms were evaluated using Standardized Patient Evaluation of Eye Dryness (SPEED) and Ocular Surface Disease Index (OSDI) questionnaires. Aqueous tear secretion was evaluated with the Schirmer test II. The number of expressible meibomian glands was evaluated with a slit-lamp-aided standardized evaluator. Lipid layer thickness (LLT), blink/incomplete blink rates and meibography were measured with the LipiView® II interferometer. The extent of the meibomian gland dropout was graded using a meiboscale. The younger age group had higher subjective symptom severity, as reflected by higher SPEED (p<0.001) and OSDI scores (p=0.051). The SPEED scores negatively correlated with LLT in all patients (r=-0.136, p<0.001). Younger patients also had thinner average LLT (p<0.001), lower meiboscale (p<0.001) and a higher number of expressible meibomian glands (p<0.001). Additionally, they had significantly more total blinks (p<0.001), incomplete blinks (p<0.001), and incomplete blink rate (p=0.006). Manifestations of DED vary with age. In our cohort, younger age patients had more symptoms and blinks, which may have resulted from thinner LLT as the structure and function of the meibomian glands were affected less than in middle and older age patients.

Assessment of tear film lipid layer thickness in patients with Meibomian gland dysfunction at different ages

BackgroundTo evaluate the correlations between lipid layer thickness (LLT) and morphology and function of the meibomian glands in patients who were diagnosed as meibomian gland dysfunction (MGD) in different age groups.MethodsPatients who have diagnosed as obstructive MGD were included in this prospective, cross-sectional study. Patients were divided into three groups: young (ages 20–39 years), middle-aged (ages 40–59 years), and older (aged ≥60 years). All patients completed an Ocular Surface Disease Index (OSDI) questionnaire and were evaluated for LLT, tear meniscus height (TMH), noninvasive tear film break-up time (NI-BUT) measurement, invasive TBUT (ITBUT), corneal fluoresceinstaining (CFS) score, eyelid margin abnormalities, Schirmer I test, and MG function and morphology, by using the Keratograph 5 and LipiView interferometer.ResultsTwo hundred and nine patients (209 eyes) were included. The median LLT of all patient was 57 nm (IQR, 36.5 nm), and the LLT values were significantly different among the young group (median, 51 nm; IQR, 23.5 nm), middle-aged group (median, 59.5 nm; IQR 46.5 nm) and older group (median, 62 nm; IQR, 42.5 nm) (P = 0.033, Kruskal-Wallis test). In regression analyses controlling for confounder factors sex and MG loss, the LLT was positively correlated with age (β = 5.539, P = 0.001). There was a negative correlation between LLT and MG dropout in the all (r = − 0.527, P < 0.001), young (r = − 0.536, P < 0.001), middle-aged (r = − 0.576, P < 0.001), and older (r = − 0.501, P < 0.001) groups. LLT was positively correlated with the MG expressibility in the all (r = 0.202, P = 0.003), middle-aged (r = 0.280, P = 0.044) and older (r = 0.452, p < 0.001) groups, but it was no statistical significance in the young group (r = 0.007, P = 0.949).ConclusionsThe thickness of LLT was increased with age and significantly correlated with both MG secretion and morphology in middle-aged and older patients with obstructive MGD. LLT measurement is a useful screening tool for detecting obstructive MGD and age as an influential factor should be accounted for when interpreting the meaning of the LLT value.Trial registrationNCT02481167; Registered 25 June, 2015.

Changes of the tear film lipid layer thickness after cataract surgery in patients with diabetes mellitus.

To evaluate changes in the tear film lipid layer thickness (LLT) in cataract patients with diabetes mellitus (DM) after cataract surgery. We recruited consecutive cataract patients and recorded data regarding DM condition. Lipid layer thickness (LLT) and partial blinks rates measured with the LipiView interferometer, tear break-up time (TBUT) and Schirmer's tests, and dry eye symptoms evaluated with the Ocular Surface Disease Index (OSDI) questionnaire were conducted before and one month after cataract surgery. Finally, 38 age-related cataract (ARC) and 31 diabetic cataract (DC) patients were available for analysis. No significant difference in preoperative LLT and partial blink rates was found between ARC and DC group. However, preoperative TBUT and Schirmer's test results were significantly lower in DC group compared to ARC group (both p<0.001). DC group showed higher preoperative OSDI score with no significant difference than ARC group (p=0.279). In DC group, LLT was significantly thinner in cases with longer duration of DM (over 10years) than in those with shorter duration (p<0.001). One month after surgery, LLT of DC group was significantly thinner than at baseline (pre: 65.7±23.3, post: 51.3±17.1, p=0.002). While in ARC group, LLT had no significant difference before and after cataract surgery (pre: 67.1±23.4, post: 60.2±21.1, p=0.078). Compared to baseline data, there was no statistically significant difference between two groups in the partial blink rates, TBUT and Schirmer's test results after cataract surgery (p>0.05). Ocular Surface Disease Index (OSDI) scores were significantly higher after surgery than at baseline in both ARC (pre: 8.9±8.4, post: 12.4±8.5, p=0.003) and DC group (pre: 11.4±10.3, post: 18.5±8.5, p=0.001). Multivariate linear regression analysis showed OSDI scores were associated with LLT either before or after cataract surgery (β=-0.862, p<0.001 and β=-0.592, p<0.001, respectively). The tear film LLT is correlated with duration of DM and becomes significantly thinner one month after cataract surgery, leading to the aggravation of dry eye symptoms.

Meibum lipid hydrocarbon chain branching and rheology after hematopoietic stem cell transplantation

PurposeMeibum from donors who have had hematological stem cell transplantations (MHSCT) are susceptible to severe dry eye symptoms and exhibit very high lipid order (stiffness) compared with meibum from donors without dry eye (Mn). Since lipid order could have functional consequences, we compared the rheology and composition of Mn and MHSCT to measure meibum compositional, structural and functional relationships. MethodsThe rheology and composition was measured using Langmuir trough and 1H NMR spectroscopy, respectively. ResultsMHSCT and Mn was studied from 16 to 43 donors, respectively, using NMR spectroscopy. MHSCT contained significantly 16% more straight chain and 24% less iso-chain hydrocarbons compared with Mn. The cholesteryl ester to wax ester molar ratio, and hydrocarbon chain unsaturation were not significantly different, for MHSCT compared with Mn.Surface pressure-area isotherms of meibum from 30 donors without dry-eye were grouped into 4 pools (PC) and meibum from 32 donors with dry eye who had hematopoietic stem cell transplantation (PT) were grouped into 3 pools. Above 15 years of age the Пmax and (Cs−1)max increased with age for both the PC and the PT cohorts. (Cs−1)max values were higher for PT samples compared with age matched PC samples, indicating they had higher elasticity and stiffness. A more ordered lipid could contribute to the formation of a discontinuous patchy tear film lipid layer, which in turn results in deteriorated spreading, and decreased surface elasticity. ConclusionsThe composition and rheology of meibum from donors with dry eye and who have had HSCT support the idea from other studies that more ordered meibum may contribute to or be a marker of dry eye.

Interactions of polar lipids with cholesteryl ester multilayers elucidate tear film lipid layer structure

PurposeThe tear film lipid layer (TFLL) covers the tear film, stabilizing it and providing a protective barrier against the environment. The TFLL is divided into polar and non-polar sublayers, but the interplay between lipid classes in these sublayers and the structure-function relationship of the TFLL remains poorly characterized. This study aims to provide insight into TFLL function by elucidating the interactions between polar and non-polar TFLL lipids at the molecular level. MethodsMixed films of polar O-acyl-ω-hydroxy fatty acids (OAHFA) or phospholipids and non-polar cholesteryl esters (CE) were used as a model of the TFLL. The organization of the films was studied by using a combination of Brewster angle and fluorescence microscopy in a Langmuir trough system. In addition, the evaporation resistance of the lipid films was evaluated. ResultsPhospholipids and OAHFAs induced the formation of a stable multilamellar CE film. The formation of this film was driven by the interdigitation of acyl chains between the monolayer of polar lipids and the CE multilayer lamellae. Surprisingly, the multilayer structure was destabilized by both low and high concentrations of polar lipids. In addition, the CE multilayer was no more effective in resisting the evaporation of water than a polar lipid monolayer. ConclusionsFormation of multilamellar films by major tear film lipids suggest that the TFLL may have a similar structure. Moreover, in contrast to the current understanding, polar TFLL lipids may not mainly act by stabilizing the non-polar TFLL sublayer, but through a direct evaporation resistant effect.