The international workshop on meibomian gland dysfunction: report of the subcommittee on anatomy, physiology, and pathophysiology of the meibomian gland

Comparison of different lipid staining methods in human meibomian gland epithelial cells

This study aimed to compare the utility of four different dyes for intracellular lipid detection in immortalized human meibomian gland epithelial cells (IHMGECs). IHMGECs were cultured in a serum-containing medium for 10 days in the presence or absence of Roxadustat (Roxa), a known inducer of IHMGEC differentiation. Cells were then fixed and stained with Oil Red O (ORO), Sudan III (SIII), LipidTOX green (LT), or Nile Red (NR). IHMGECs were evaluated for the number, size, and area of stained intracellular lipid vesicles or the intensity of staining using bright field (ORO, SIII) or fluorescence (LT, NR) microscopy. Data were captured with ImageJ and analyzed with Student's two-tailed t-test. Our findings demonstrate that different staining methods can yield significantly different patterns of intracellular lipid quantity and/or distribution in IHMGECs. ORO and SIII significantly increased the size and area of lipid-containing vesicles in Roxa-treated cells. Neither stain showed a change in the number of vesicles during IHMGEC differentiation. Vesicle size was significantly greater in cells stained with ORO, as compared to SIII. In addtion, LT, but not NR, showed a significant increase in intracellular lipid intensity in IHMGECs following Roxa -induced differentiation. Our results demonstrate significant differences in the distribution patterns and intensities of lipid-containing vesicles in IHMGECs after staining with ORO, SIII, LT, and NR. ORO, SIII, and LT, but not NR staining, are helpful methods to help identify and quantitate the extent of intracellular lipid accumulation during IHMGEC differentiation.

Prolonged facemask wearing among hospital workers and dry eye - a mixed-methods study

BACKGROUND

Prolonged facemask wearing may have negatively affected essential workers with dry eye. We conducted a mixed-methods study to examine and understand the associations of the ocular surface, periocular environment, and dry eye-related symptoms among hospital workers across the job spectrum with prolonged facemask use.

METHODS

We recruited clinical and non-clinical hospital workers with self-reported symptoms of dry eye and prolonged facemask use. We measured symptoms using the 5-item Dry Eye Questionnaire and the Ocular Surface Disease Index (OSDI). Objective ocular signs included corneal and conjunctival staining, fluorescein tear break up time (TBUT), meibography, tear film interferometry, and periocular humidity. We compared symptoms and signs across levels of periocular humidity, dry eye severity, facemask type, and job type. Participants with moderate or severe dry eye symptoms (OSDI > = 23) were invited for a semi-structured, one-on-one interview.

RESULTS

We enrolled 20 clinical and 21 non-clinical hospital workers: 27% were 40 years or older, 76% were female, 29% reported a race other than White, and 20% were Hispanic. Seventeen individuals participated in the semi-structured interviews. From the quantitative analyses, we found that 90% of participants reported worsened severity of dry eye at work due to facemasks. Although wearing facemasks resulted in higher periocular humidity levels compared with not wearing facemasks, 66% participants reported increased airflow over their eyes. Findings from the qualitative interviews supported the finding that use of facemasks worsened dry eye symptoms, especially when facemasks were not fitted around the nose. The data did not suggest that non-clinical hospital workers experienced a greater impact of dry eye than clinical workers.

CONCLUSIONS

Healthcare providers and patients with dry eye should be educated about the discomfort and the ocular surface health risks associated with inadequately fitted facemasks. Wearing a fitted facemask with a pliable nose wire appears to mitigate the upward airflow.

Evaluation of the Efficacy and Safety of Topical 0.05% Cyclosporine Eye Drops (II) in the Treatment of Dry Eye Associated with Primary Sjögren's Syndrome

PURPOSE

To evaluate the efficacy and safety of 0.05% cyclosporine eye drops (II) for the treatment of primary Sjögren's syndrome-associated dry eye (PSSDE).

METHODS

Sixty patients with PSSDE were randomly divided into three groups, received treatment with 0.05% cyclosporine (C group), artificial tears (S group) or their combination (CS group). The evaluation indicators were evaluated at baseline and at weeks 2, 4 and 12.

RESULTS

The symptoms of C and CS groups were reduced significantly. The signs [schirmer I test (F = 4.838, p = .011), ocular staining score (F = 7.961, p = .001) and tear break-up time (F = 9.283, p < .001)] were significantly different between S and C groups as well as S and CS groups. The tear meniscus height (F = 3.197, p = .048) was significantly different between S and CS groups. No serious adverse events occurred.

CONCLUSION

0.05% cyclosporine is an effective and safe treatment for patients with PSSDE.

Recent advances in age-related meibomian gland dysfunction (ARMGD)

Meibomian glands (MGs), located within the tarsal plate of the eyelid, secrete meibum which is the lipid-rich secretion necessary for stabilizing the tear film and preventing tear evaporation. Changes in the quality and quantity of meibum produced causes MG dysfunction (MGD), the leading cause of evaporative dry eye disease (EDED). MGD is an underdiagnosed disease and it is estimated that, in the US, approximately 70 % of the population over 60 have MGD. Three forms of MGD occur based on their meibum secretion: hyposecretory, obstructive, and hypersecretory MGD. The pathophysiology of MGD remains poorly understood, however aging is the primary risk factor. With age, MGs undergo various age-related changes, including decreased acinar basal cell proliferation, hyperkeratinization, MG atrophy, and eventual MG drop-out, leading to age-related MGD (ARMGD). Additionally, studies have suggested that MGs can suffer inflammatory cell infiltration and changes innervation patterns with aging, which could also contribute towards ARMGD. This review focuses on how the aging process affects the MG, and more importantly, how age-related changes to the MG can lead to MG atrophy and MG drop-out, ultimately leading to ARMGD. This review also highlights the most recent developments in potential therapeutic interventions for ARMGD.

Culture of primary human meibomian gland cells from surgically excised eyelid tissue

Meibomian gland dysfunction is one of the most common ocular diseases, with therapeutic treatment being primarily palliative due to our incomplete understanding of meibomian gland (MG) pathophysiology. To progress in vitro studies of human MG, this study describes a comprehensive protocol, with detailed troubleshooting, for the successful isolation, cultivation and cryopreservation of primary MG cells using biopsy-size segments of human eyelid tissue that would otherwise be discarded during surgery. MG acini were isolated and used to establish and propagate lipid-producing primary human MG cells. The primary cell viability during culture procedure was maintained through the application of Rho-associated coiled-coil containing protein kinase inhibitor (Y-27632, 10 μM) and collagen I from rat tails. Transcriptomic analysis of differentiated primary human MG cells confirmed cell origin and revealed high-level expression of many lipogenesis-related genes such as stearoyl-CoA desaturase (SCD), ELOVL Fatty Acid Elongase 1 (ELOVL1) and fatty acid synthase (FASN). Primary tarsal plate fibroblasts were also successfully isolated, cultured and cryopreserved. Established primary human MG cells and tarsal plate fibroblasts presented in this study have potential for applications in 3D models and bioengineered tissue that facilitate research in understanding of MG biology and pathophysiology.

Morphological changes in the meibomian gland in children with tic disorders

Background

Since blinking accelerates meibomian gland (MG) expression, abnormal blinking in children with tic disorders may be associated with the morphological changes of the MGs. Our study aimed to quantitively evaluate the morphology of the MG in these children.

Methods

In this prospective case-control study, we examined 68 eyes of 68 children with tic disorders, 47 eyes of 47 children with dry eye, and 45 eyes of 45 healthy children at the Hangzhou Branch of the Eye Hospital of Wenzhou Medical University from October 2020 to March 2021. We used an Oculus Keratograph 5M (K5M) to capture the MG images, noninvasive breakup time (NIBUT), and tear meniscus height (TMH). An automated method was used to analyze MG length, width, area, gland diameter deformation index (DI), and gland signal index (SI). Parameters across the three groups were assessed using Kruskal-Wallis test followed by Mann-Whitney test with Bonferroni correction for multiple comparisons.

Results

The eyes in the tic disorders group exhibited lower MG length and area values compared with those of the other groups (all P values <0.001) and lower MG width values compared with those of children in the dry eye group (P=0.009). The tic disorder and dry eye groups both had a larger percentage of eyes with a U-shaped MG duct when compared with the control group (P<0.001 and P=0.017). The dry eye group had the lowest TMH and NIBUT values (both P values <0.001). The NIBUT values in the tic disorder group were lower than those in the control group (P<0.001). No significant correlations were detected between clinical tests and MG morphology in any of the groups.

Conclusions

Blinking disorders have a significant impact on MG morphology. In children with tic disorders, more attention should be devoted to monitoring the MG over time.

Study of pathological processes of meibomian gland dysfunction by in vitro culture airlifting conditions

Meibomian gland dysfunction (MGD) is a group of disorders linked by functional abnormalities of the meibomian glands. Current studies on MGD pathogenesis focus on meibomian gland cells, providing information on a single cell's response to experimental manipulation, and do not maintain the architecture of an intact meibomian gland acinus and the acinar epithelial cells' secretion state in vivo. In this study, rat meibomian gland explants were cultured by a Transwell chamber-assisted method under an air-liquid interface (airlift) in vitro for 96 h. Analyses for tissue viability, histology, biomarker expression, and lipid accumulation were performed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and TUNEL assays, hematoxylin and eosin (H&E) staining, immunofluorescence, Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), transmission electron microscopy (TEM), and western blotting (WB). MTT, TUNEL, and H&E staining indicated better tissue viability and morphology than the submerged conditions used in previous studies. Levels of MGD biomarkers, including keratin 1 (KRT1) and 14 (KRT14) and peroxisome proliferator-activated receptor-gamma (PPAR-γ), along with oxidative stress markers, including reactive oxygen species, malondialdehyde, and 4-hydroxy-2-nonenal, gradually increased over culture time. The MGD pathophysiological changes and biomarker expression of meibomian gland explants cultured under airlift conditions were similar to those reported by previous studies, indicating that abnormal acinar cell differentiation and glandular epithelial cell hyperkeratosis may contribute to obstructive MGD occurrence.

Skin-Only Versus Skin-Plus-Orbicularis Resection Blepharoplasty: An Elaborated Analysis of Early- and Long-Term Effects on Corneal Nerves, Meibomian Glands, Dry Eye Parameters, and Eyebrow Position

PURPOSE

To evaluate the early- and long-term effects of 2 different blepharoplasty techniques on corneal nerves, meibomian gland morphology, clinical parameters of dry eye disease (DED), and eyebrow position.

METHODS

This prospective, interventional study included age-sex-matched blepharoplasty patients who had a skin-only resection (24 eyes of 12 patients; Group-S) or a skin-plus-orbicularis muscle resection (24 eyes of 12 patients; Group-M) procedure. Preoperative and postoperative parameters of in vivo corneal confocal microscopy (IVCCM; corneal nerve fiber density [CNFD], nerve branch density [CNBD], and nerve fiber length), meibomian gland area loss (MGAL), DED (Schirmer I test and noninvasive tear breakup time), and eyebrow heights (lateral [LBH] and central [CBH]) were evaluated and compared between the intervention groups ( ClinicalTrials.gov , NCT05528016).

RESULTS

Compared with baseline, the CNBD of Group-S (19.91 ± 7.66 vs. 16.05 ± 7.28 branches/mm 2 , p = 0.049) and CNFD of Group-M (19.52 ± 7.45 vs. 16.80 ± 6.95 fibers/mm 2 , p = 0.028) was significantly decreased at postoperative first week. However, in both groups, IVCCM parameters returned to baseline values at postoperative first month and first year ( p > 0.05). A significant MGAL increase was observed in Group-S (18.47 ± 5.43 vs. 19.94 ± 5.31, p = 0.030) and Group-M (18.86 ± 7.06 vs. 20.12 ± 7.01, p = 0.023) at the postoperative first year, demonstrating meibomian gland atrophy. Only significant changes were observed in Group-M in LBH (16.17 ± 2.45 vs. 16.67 ± 2.28 mm, p = 0.044) and CBH (17.33 ± 2.35 vs. 17.96 ± 2.31 mm, p = 0.004) at postoperative first year.

CONCLUSIONS

Blepharoplasty with or without orbicularis resection seems to have similar effects on IVCCM, DED, and MGAL parameters. However, incorporating an orbicularis muscle resection in a blepharoplasty operation could slightly elevate the eyebrow position.

Role of instrumental factors in Meibomian gland contrast assessment

PURPOSE

Meibomian gland contrast has been suggested as a potential biomarker in Meibomian gland dysfunction. This study analysed the instrumental factors related to contrast. The objectives were to determine whether the mathematical equations used to compute gland contrast (e.g., Michelson or Yeh and Lin), impact the ability to identify abnormal individuals, to ascertain whether contrast between the gland and the background could be an effective biomarker and to assess whether using contrast-enhancement on the gland image improves its diagnostic efficacy.

METHODS

A total of 240 meibography images from 40 participants (20 controls and 20 having Meibomian gland dysfunction or blepharitis), were included. The Oculus Keratograph 5M was used to capture images from the upper and lower eyelids of each eye. The contrast of unprocessed images and those pre-processed with contrast-enhancement algorithms were analysed. Contrast was measured on the eight central glands. Two equations for contrast computation were used, and the contrast both between glands and within a gland were calculated.

RESULTS

Significant differences were found between the groups for inter-gland area in the upper (p = 0.01) and lower eyelids (p = 0.001) for contrast measured with the Michelson formula. Similar effects were observed when using the Yeh and Lin method in the upper (p = 0.01) and lower eyelids (p = 0.04). These results were obtained for images enhanced with the Keratograph 5M algorithm.

CONCLUSIONS

Meibomian gland contrast is a useful biomarker of disease related to the Meibomian glands. Contrast measurement should be determined using contrast-enhanced images in the inter-gland area. However, the method used to compute contrast did not influence the results.

Integrated multi-omics and machine learning approach reveals lipid metabolic biomarkers and signaling in age-related meibomian gland dysfunction

Meibomian gland dysfunction (MGD) is a prevalent inflammatory disorder of the ocular surface that significantly impacts patients' vision and quality of life. The underlying mechanism of aging and MGD remains largely uncharacterized. The aim of this work is to investigate lipid metabolic alterations in age-related MGD (ARMGD) through integrated proteomics, lipidomics and machine learning (ML) approach. For this purpose, we collected samples of female mouse meibomian glands (MGs) dissected from eyelids at age two months (n = 9) and two years (n = 9) for proteomic and lipidomic profilings using the liquid chromatography with tandem mass spectrometry (LC-MS/MS) method. To further identify ARMGD-related lipid biomarkers, ML model was established using the least absolute shrinkage and selection operator (LASSO) algorithm. For proteomic profiling, 375 differentially expressed proteins were detected. Functional analyses indicated the leading role of cholesterol biosynthesis in the aging process of MGs. Several proteins were proposed as potential biomarkers, including lanosterol synthase (Lss), 24-dehydrocholesterol reductase (Dhcr24), and farnesyl diphosphate farnesyl transferase 1 (Fdft1). Concomitantly, lipidomic analysis unveiled 47 lipid species that were differentially expressed and clustered into four classes. The most notable age-related alterations involved a decline in cholesteryl esters (ChE) levels and an increase in triradylglycerols (TG) levels, accompanied by significant differences in their lipid unsaturation patterns. Through ML construction, it was confirmed that ChE(26:0), ChE(26:1), and ChE(30:1) represent the most promising diagnostic molecules. The present study identified essential proteins, lipids, and signaling pathways in age-related MGD (ARMGD), providing a reference landscape to facilitate novel strategies for the disease transformation.

The Effect of Oral Isotretinoin Therapy on Meibomian Gland Characteristics in Patients with Acne Vulgaris

INTRODUCTION

The aim of the study was to determine the effect of oral isotretinoin therapy on the functional and morphological condition of the anterior segment of the eye, with particular emphasis on the meibomian glands.

METHODS

Twenty-four patients (48 eyes) with a diagnosis of acne vulgaris were involved in the survey. All patients underwent a thorough ophthalmological examination at three time points: before therapy, 3 months after the start of therapy, and 1 month after the completion of isotretinoin therapy. The physical examination included the following elements: blink rate, analysis of the lid margin abnormality score (LAS), tear film break-up time (TFBUT) and Schirmer's test, meibomian gland loss (MGL), and the evaluation of the meibum quality score (MQS) and meibum expressibility score (MES). Additionally, the total score of an ocular surface disease index (OSDI) questionnaire was analysed.

RESULTS

In comparison with pretreatment values, significant increases in OSDI during and after the treatment (p = 0.003 and p = 0.004, respectively) were observed. Substantial deterioration during the treatment was observed for MGL (p < 0.0001), MQS (p < 0.001) and LAS (p < 0.0001), while an improvement in those parameters after isotretinoin cessation was observed (p = 0.006, p = 0.02 and p = 0.0003, respectively). The frequency of using artificial eye drops was positively associated with MGL during (Spearman's rank correlation coefficient (Rs) =  + 0.31; p = 0.03) and after the cessation of the therapy (Rs =  + 0.28; p = 0.04). Meibomian gland atrophy correlated significantly with MQS during (Rs =  + 0.29; p = 0.04) and after treatment (Rs =  + 0.38; p = 0.008). The decrease in TFBUT values correlated with increased LAS (Rs = - 0.31; p = 0.03) during the course of isotretinoin usage. We found no changes in Schirmer's test or blink rates.

CONCLUSION

Isotretinoin therapy leads to increased ocular complaints related to lipid tear film component dysfunction. This is due to reversible changes in meibomian gland morphology and function observed during drug usage.

NOV03 for Signs and Symptoms of Dry Eye Disease Associated With Meibomian Gland Dysfunction: The Randomized Phase 3 MOJAVE Study

PURPOSE

To evaluate the efficacy and safety of NOV03 (perfluorohexyloctane) ophthalmic drop for the treatment of signs and symptoms of dry eye disease (DED) associated with meibomian gland dysfunction (MGD).

DESIGN

Randomized, double-masked, controlled trial.

METHODS

Patients ≥18 years of age with a history of DED and signs of MGD were randomly assigned 1:1 to treatment with NOV03 or hypotonic saline (0.6%) 4 times daily for 8 weeks. The primary sign and symptom endpoints were change from baseline to week 8 in total corneal fluorescein staining (tCFS; National Eye Institute scale) and eye dryness score (0-100 visual analog scale), respectively.

RESULTS

A total of 620 patients (NOV03, n = 311; saline, n = 309) were randomized and treated. Least-squares (LS) mean change from baseline to week 8 was statistically significantly greater for NOV03 compared with saline for both tCFS (-2.3 vs -1.1; LS mean treatment difference, -1.2 [95% confidence interval -1.7 to -0.8]; P < .001) and visual analog scale dryness score (-29.4 vs -19.2; LS mean treatment difference, -10.2 [95% CI -14.4 to -6.1]; P < .001), with statistically significant between-group differences observed as early as week 2. The incidence of ocular adverse events was similar for NOV03 (12.9%) and saline (12.3%). There were no serious adverse events and no adverse events leading to treatment discontinuation.

CONCLUSIONS

In this randomized controlled trial of patients with DED associated with MGD, NOV03 significantly reduced both signs and symptoms of DED compared with hypotonic saline control. NOV03 was well tolerated, with an adverse event profile similar to that of saline.

Ocular surface disease: a known yet overlooked side effect of topical glaucoma therapy

Ocular surface disease (OSD), a disorder affecting the lacrimal and meibomian glands and the corneal and conjunctival epithelium, is a well-known complication of topical glaucoma therapy. OSD can present as a new or pre-existing condition that virtually any anti-glaucoma formulation can exacerbate. As such, both glaucoma and OSD frequently coexist. Typical OSD symptoms include ocular discomfort, redness, burning, and dryness, whereas signs include periorbital and eyelid skin pigmentation, conjunctival scarring, and superficial punctate keratitis. Pressure-lowering eyedrops can cause toxic, allergic, and inflammatory reactions on the ocular surface. The latter can result from either preservatives or direct toxicity from the active molecule. Although usually mild, OSD can cause significant symptoms that lead to poor quality of life, decreased compliance to therapy, glaucoma progression, and worse visual outcomes. Given the chronic nature of glaucoma, lack of curative therapy, and subsequent lifelong treatment, addressing OSD is necessary. This manuscript aims to provide an up-to-date overview of OSD's signs, symptoms, and pathogenic mechanisms from glaucoma therapy toxicity.

Impact of Exposomes on Ocular Surface Diseases

Ocular surface diseases (OSDs) are significant causes of ocular morbidity, and are often associated with chronic inflammation, redness, irritation, discomfort, and pain. In severe OSDs, loss of vision can result from ocular surface failure, characterised by limbal stem cell deficiencies, corneal vascularisation, corneal opacification, and surface keratinisation. External and internal exposomes are measures of environmental factors that individuals are exposed to, and have been increasingly studied for their impact on ocular surface diseases. External exposomes consist of external environmental factors such as dust, pollution, and stress; internal exposomes consist of the surface microbiome, gut microflora, and oxidative stress. Concerning internal exposomes, alterations in the commensal ocular surface microbiome of patients with OSDs are increasingly reported due to advancements in metagenomics using next-generation sequencing. Changes in the microbiome may be a consequence of the underlying disease processes or may have a role in the pathogenesis of OSDs. Understanding the changes in the ocular surface microbiome and the impact of various other exposomes may also help to establish the causative factors underlying ocular surface inflammation and scarring, the hallmarks of OSDs. This review provides a summary of the current evidence on exposomes in various OSDs.

Relationship Between Human Meibum Lipid Composition and the Severity of Meibomian Gland Dysfunction: A Spectroscopic Analysis

Purpose

Information on the relationship between meibum lipid composition and severity of meibomian gland dysfunction (MGD) is limited. The purpose of this study was to analyze the molecular components of meibum collected from individuals with no MGD, mild-to-moderate MGD, and severe MGD.

Methods

Adults with and without MGD were enrolled in a prospective, multicenter, exploratory clinical trial (ClinicalTrials.gov Identifier: NCT01979887). Molar ratios of cholesteryl ester to wax ester (RCE/WE) and aldehyde to wax ester (Rald/WE) in meibum samples were measured with 1H-NMR spectroscopy. Results were evaluated for participants grouped by MGD disease status and severity (non-MGD, mild-to-moderate MGD, and severe MGD), as defined by maximum meibum quality scores, Schirmer test results, and Subject Ocular Symptom Questionnaire responses.

Results

Sixty-nine meibum samples from 69 individuals were included in the analysis: 24 non-MGD, 24 mild-to-moderate MGD, and 21 severe MGD. Mean RCE/WE was 0.29 in non-MGD, 0.14 in mild-to-moderate MGD (P = 0.038 vs. non-MGD, 51% lower), and 0.07 in severe MGD (P = 0.16 vs. mild-to-moderate MGD, 52% lower; P = 0.002 vs. non-MGD, 76% lower). Mean Rald/WE was 0.00022 in non-MGD, 0.00083 in mild-to-moderate MGD (P = 0.07 vs. non-MGD, 277% higher), and 0.0024 in severe MGD (P = 0.003 vs. mild-to-moderate MGD, 190% higher; P < 0.001 vs. non-MGD, 992% higher).

Conclusions

RCE/WE was lowest and Rald/WE was highest in the severe MGD cohort, suggesting that these meibum constituent molar ratios may result from the pathophysiology associated with MGD and can impact ocular surface lipid and tear film homeostasis. These findings may potentially help identify targets for MGD treatment.

Meibomian gland stem/progenitor cells: The hunt for gland renewal

Meibomian glands (MGs) secrete lipid (meibum) onto the ocular surface to form the outermost layer of the tear film. Proper meibum secretion is essential for stabilizing the tear film, reducing aqueous tear evaporation, and maintaining the homeostasis of the ocular surface. Atrophy of MG as occurs with aging, leads to reduction of meibum secretion, loss of ocular surface homeostasis and evaporative dry eye disease (EDED). Since MGs are holocrine glands, secretion of meibum requires continuous self-renewal of lipid-secreting acinar meibocytes by stem/progenitor cells, whose proliferative potential is dramatically reduced with age leading to MG atrophy and an age-related meibomian gland dysfunction (ARMGD). Understanding the cellular and molecular mechanisms regulating meibocyte stem/progenitor cell maintenance and renewal may provide novel approaches to regenerating MG and treating EDED. Towards that end, recent label retaining cell and lineage-tracing experiments as well as knock-out transgenic mouse studies have begun to identify the location and identities of meibocyte progenitor cells and potential growth and transcription factors that may regulate meibocyte renewal. In addition, recent reports have shown that ARMGD may be reversed by novel therapeutics in mice. Herein, we discuss our current understanding of meibocyte stem/progenitor cells and the hunt for gland renewal.

Meibomian gland development: Where, when and how?

The Meibomian gland (MG) is an indispensable adnexal structure of eye that produces meibum, an important defensive component for maintaining ocular homeostasis. Normal development and maintenance of the MGs is required for ocular health since atrophic MGs and disturbances in composition and/or secretion of meibum result in major ocular pathologies, collectively termed as Meibomian gland dysfunction (MGD). Currently available therapies for MGD merely provide symptomatic relief and do not treat the underlying deficiency of the MGs. Hence, a thorough understanding of the timeline of MG development, maturation and aging is required for regenerative purposes along with signaling molecules & pathways controlling proper differentiation of MG lineage in mammalian eye. Understanding the factors that contribute to the development of MGs, developmental abnormalities of MGs, and changes in the quality & quantity of meibum with developing phases of MGs are essential for developing potential treatments for MGD. In this review, we compiled a timeline of events and the factors involved in the structural and functional development of MGs and the associated developmental defects of MGs during development, maturation and aging.

TFOS Lifestyle: Impact of nutrition on the ocular surface

Nutrients, required by human bodies to perform life-sustaining functions, are obtained from the diet. They are broadly classified into macronutrients (carbohydrates, lipids, and proteins), micronutrients (vitamins and minerals) and water. All nutrients serve as a source of energy, provide structural support to the body and/or regulate the chemical processes of the body. Food and drinks also consist of non-nutrients that may be beneficial (e.g., antioxidants) or harmful (e.g., dyes or preservatives added to processed foods) to the body and the ocular surface. There is also a complex interplay between systemic disorders and an individual's nutritional status. Changes in the gut microbiome may lead to alterations at the ocular surface. Poor nutrition may exacerbate select systemic conditions. Similarly, certain systemic conditions may affect the uptake, processing and distribution of nutrients by the body. These disorders may lead to deficiencies in micro- and macro-nutrients that are important in maintaining ocular surface health. Medications used to treat these conditions may also cause ocular surface changes. The prevalence of nutrition-related chronic diseases is climbing worldwide. This report sought to review the evidence supporting the impact of nutrition on the ocular surface, either directly or as a consequence of the chronic diseases that result. To address a key question, a systematic review investigated the effects of intentional food restriction on ocular surface health; of the 25 included studies, most investigated Ramadan fasting (56%), followed by bariatric surgery (16%), anorexia nervosa (16%), but none were judged to be of high quality, with no randomized-controlled trials.

TFOS Lifestyle: Impact of elective medications and procedures on the ocular surface

The word "elective" refers to medications and procedures undertaken by choice or with a lower grade of prioritization. Patients usually use elective medications or undergo elective procedures to treat pathologic conditions or for cosmetic enhancement, impacting their lifestyle positively and, thus, improving their quality of life. However, those interventions can affect the homeostasis of the tear film and ocular surface. Consequently, they generate signs and symptoms that could impair the patient's quality of life. This report describes the impact of elective topical and systemic medications and procedures on the ocular surface and the underlying mechanisms. Moreover, elective procedures performed for ocular diseases, cosmetic enhancement, and non-ophthalmic interventions, such as radiotherapy and bariatric surgery, are discussed. The report also evaluates significant anatomical and biological consequences of non-urgent interventions to the ocular surface, such as neuropathic and neurotrophic keratopathies. Besides that, it provides an overview of the prophylaxis and management of pathological conditions resulting from the studied interventions and suggests areas for future research. The report also contains a systematic review investigating the quality of life among people who have undergone small incision lenticule extraction (SMILE). Overall, SMILE refractive surgery seems to cause more vision disturbances than LASIK in the first month post-surgery, but less dry eye symptoms in long-term follow up.

Transitory alkali exposure on meibomian gland orifices induces meibomian gland dysfunction

PURPOSE

To determine pathological changes of meibomian glands (MGs) after transient exposure of the rat eyelid margin to alkali solution.

METHODS

Filter paper infiltrated with 1 N sodium hydroxide solution was applied to the eyelid margin of Sprague-Dawley rats for 30 s under general anesthesia, without touching the conjunctiva, after which the ocular surface and eyelid margin were examined by slit-lamp microscopy. In vivo confocal microscopy and stereomicroscopy were subsequently applied to observe MG morphology on day 5, day 10 and day 30 post alkali injury. Eyelid cross-sections were processed for H&E staining, Oil red O staining and immunofluorescent staining.

RESULTS

After alkali injury, there was marked plugging of MG orifices, telangiectasia and hypertrophy of the eyelid margin, while corneal epithelium was intact at post-injury days 5 and 10. However, 30 days after alkali injury, mild corneal epithelial damage was observed. Degeneration of MG acini was observed at days 5 and became aggravated at days 10 and 30, along with MG duct dilation and acini loss. Oil red O staining showed lipid accumulation in the dilated duct. Inflammatory cell infiltration and the presence of apoptotic cells was seen in the MG loci 5 days post injury, but diminished at days 10 and 30. Cytokeratin 10 expression was increased in dilated duct, while cytokeratin 14, PPAR-γ, Ki67 and LRIG1 expression were decreased in the acini of injured loci.

CONCLUSIONS

Transitory alkali exposure of the rat eyelid margin obstructs the MG orifice and induces pathological changes of MG dysfunction.

TFOS Lifestyle: Impact of cosmetics on the ocular surface

In this report the use of eye cosmetic products and procedures and how this represents a lifestyle challenge that may exacerbate or promote the development of ocular surface and adnexal disease is discussed. Multiple aspects of eye cosmetics are addressed, including their history and market value, psychological and social impacts, possible problems associated with cosmetic ingredients, products, and procedures, and regulations for eye cosmetic use. In addition, a systematic review that critically appraises randomized controlled trial evidence concerning the ocular effects of eyelash growth products is included. The findings of this systematic review highlight the evidence gaps and indicate future directions for research to focus on ocular surface outcomes associated with eyelash growth products.

Efficacy and safety of AZR-MD-001 selenium sulfide ophthalmic ointment in adults with meibomian gland dysfunction: A vehicle-controlled, randomized clinical trial

PURPOSE

Meibomian gland dysfunction (MGD) is a chronic progressive disease with downstream effects on ocular signs and symptoms. AZR-MD-001 is a selenium sulfide ophthalmic ointment that was investigated as a potential treatment option for patients with MGD.

METHODS

A Phase 2, multi-center, double-masked, parallel group study was conducted across 29 sites, with 245 patients randomized 1:1:1 to AZR-MD-001 0.5%, AZR-MD-001 1.0% or vehicle applied to the lower eyelid, twice weekly. Patients were eligible for the trial if they presented with signs and symptoms of MGD. Co-primary efficacy endpoints were the changes from baseline in number of open glands (Meibomian Glands Yielding Liquid Secretion [MGYLS] score) and patient-reported ocular surface symptoms (Ocular Surface Disease Index [OSDI] total score) at Month 3. Efficacy outcomes were captured at Day 14, Month 1.5 and Month 3. Safety and tolerability were assessed for treatment-emergent adverse events (TEAEs).

RESULTS

AZR-MD-001 0.5% (n = 82 patients) treatment resulted in significant improvements in MGYLS score, with patients experiencing an average increase from baseline of 4.2 and 2.4 open glands secreting meibum for the drug and vehicle, respectively (p < 0.001) and from baseline a mean OSDI total score improvement of 7.3 and 3.8 for the drug and vehicle, respectively (p < 0.05). Most TEAEs were mild and transient, with 3 serious adverse events (SAEs) reported with AZR-MD-001 (none related to study drug).

CONCLUSIONS

Co-primary endpoints were met for AZR-MD-001 0.5% at Month 3, with a statistically significant improvement in the signs and symptoms of MGD. AZR-MD-001 was safe and well tolerated.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03652051, ANZCTR Registration Number: AZ201801.

A Retrospective Analysis of Tear Film and Blink Parameters in Patients With Ocular Surface Disease

OBJECTIVES

We had two objectives: (1) to investigate differences in tear film and blink parameters in patients with six ocular surface diseases (OSD): ocular graft versus host disease (oGVHD), Stevens-Johnson syndrome (SJS), lax eyelid syndrome, meibomian gland dysfunction (MGD), obstructive sleep apnea, and dry eye disease; and (2) to characterize the relationships between lipid layer thickness (LLT), meiboscore, Schirmer I test, and three blink parameters: partial blink rate (PBR), interblink interval (IBI), and interpalpebral fissure height (IPFH) in this group of patients.

METHODS

This is a single-site retrospective analysis of 228 patients (456 eyes) with six different primary OSD at Loyola University Medical Center between January 2018 and July 2020. Objective parameters included: LLT, IBI, PBR, IPFH, Pult meiboscore, and Schirmer I score. Linear mixed effects models were used to analyze the relationships between these parameters.

RESULTS

The meiboscore was highest in patients with SJS compared with the other five groups. There was significant variability in IPFH across different groups, with patients with oGVHD having the smallest height. An increase in IPFH was associated with increases in IBI, PBR, and Schirmer score. Patients with no partial blinks demonstrated a statistically significant higher IBI than patients who showed 1%-50% partial blinks. Finally, no statistically significant relationship was found between the following: (1) meiboscore and LLT, (2) OSDI and IPFH, (3) Schirmer score and IBI, or (4) LLT and IBI.

CONCLUSIONS

There were fewer than anticipated differences in objective tear film and blink parameters between patients with six different OSD. A statistically significant association was found between IPFH and Schirmer score and IPFH and IBI, representing new findings in tear film research. Further investigation of the relationship between IPFH and IBI is needed.

3% diquafosol sodium eye drops in Chinese patients with dry eye: a phase IV study

Introduction

The efficacy and safety of 3% diquafosol sodium eye drops in Chinese patients with dry eye in the real-world setting remains unclear.

Methods

3099 patients with dry eye symptoms were screened according to Asia Dry Eye Society latest recommendation. Among them, 3000 patients were enrolled for a phase IV study. We followed up with multiple clinical characteristics including corneal fluorescein staining, tear break up time, Schirmer's tests, visual acuity, intraocular pressure, and others. The follow ups were performed at baseline, 2 weeks and 4 weeks after treatment.

Results

Based on the results of corneal fluorescein staining and tear break up time, all age and gender subgroups exhibited obvious alleviation of the symptoms among the patients with dry eye, and the data in elderly group showed the most significant alleviation. All the adverse drug reactions (ADRs, 6.17%) were recorded, among which 6% local ocular ADRs were included. Meanwhile, mild ADRs (91.8%) accounted for the most. Most of the ADRs (89.75%) got a quick and full recovery, with an average time at 15.6 days. 1.37% of patients dropped out of the study due to ADRs.

Discussion

The use of 3% diquafosol sodium eye drop is effective and safe in the treatment of dry eye, with a low incidence of ADRs showing mild symptoms. This trial was registered at Chinese Clinical Trial Registry ID: ChiCTR1900021999 (Registration Date: 19/03/2019).

In vitro evaluation of multiple antibacterial agents for the treatment of chronic staphylococcal anterior blepharitis

OBJECTIVE

To evaluate the bactericidal efficacy of several compounds used in the treatment of chronic staphylococcal anterior blepharitis through an in vitro study.

MATERIALS AND METHODS

Standard commercial strains of Staphylococcus aureus (SAu) (ATCC 25923 Culti-Loops) and coagulase-negative Staphylococcus (CoNS) (ATCC 12228 Culti-Loops) were cultured. Susceptibility tests were performed to vancomycin 30 μg, netilmicin 30 μg, hypochlorous acid (HOCl) 0.01% (Ocudox™, Brill®), Melaleuca alternifolia leaf oil (MeAl) (Navyblef® Daily Care, NOVAX ®) and 1% chlorhexidine digluconate (DGCH) (Cristalmina™, Salvat®) using the agar disk diffusion method (Rosco Neo-Sensitabs®). After 24 hours, the induced halos were measured with automatic calipers. The results were analyzed using the EUCAST- and CLSI potency Neo-Sensitabs® guidelines.

RESULTS

Vancomycin induced a halo of 22.37 mm and 21.81 mm in SAu and CoNS, respectively. Netilmicin produced halos of 24.45 mm in SAu and 32.49 mm in CoNS. MeAl induced halos of 12.65 mm in SAu and 15.83 mm in CoNS. A 12.11 mm halo was found in SAu and an 18.38 mm halo in CoNS using HOCl. DGCH produced halos of 26.55 mm and 23.12 mm in SAu and CoNS, respectively.

CONCLUSION

Netilmicin and vancomycin demonstrated antibiotic activity against both pathogens, so they can be alternative rescue therapies to treat chronic staphylococcal blepharitis. DGCH has efficacy against both comparable to antibiotics, while HOCl and MeAl show less efficacy.

In Vitro Inhibition of Evaporation with Perfluorohexyloctane, an Eye Drop for Dry Eye Disease

Objective

Perfluorohexyloctane (PFHO) MIEBO^TM, formerly (NOV03) is a single component, water-free eye drop approved by the Food and Drug Administration in the United States for the treatment of dry eye disease. We evaluated the in vitro inhibitory effect of PFHO on the evaporation rate (R_evap) of saline.

Methods

Evaporation rates were measured gravimetrically at 25°C or 35°C. The evaporation rate (R_evap) of phosphate-buffered saline (PBS) was measured following the application of 11-200 µL PFHO or 100 µL artificial tears (Soothe XP [Bausch + Lomb, Bridgewater, New Jersey], Systane Balance [Alcon, Fort Worth, Texas], and Systane Ultra [Alcon]). The effect of PFHO on the R_evap of PBS was further evaluated following the addition of 50 mg/mL mucin to PBS and compared with that of meibum lipid collected from a 68 year-old White volunteer.

Results

At 25°C the mean (SEM) R_evap of PBS alone or PFHO alone was 4.06 (0.06) and 0.137 (0.004) µm/min, respectively. Layering 100 µL PFHO over PBS inhibited the R_evap of PBS by 81% (P < 0.0001), whereas artificial tears had no effect. The presence of mucin attenuated the inhibition of the R_evap of PBS by PFHO by 17% (P < 0.0001). At 35°C, the R_evap of PBS was inhibited by 88% when layering 100 µL PFHO over PBS and 28% when applying a single 11 µL drop of PFHO (P value < 0.0001 for both). Meibum lipid inhibited the R_evap of PBS by 8% at this temperature, whereas the combination of a drop of PFHO plus meibum inhibited the R_evap of PBS by 34%.

Conclusions

PFHO significantly inhibited the R_evap of saline in this in vitro model. The data support the idea that PHFO may form an antievaporative layer on the tear film surface and may be a functional substitute for the native tear-film lipid layer in patients with dry eye disease.

Association of meibomian gland morphology with orifice plugging and lid margin thickening in meibomian gland dysfunction patients

PURPOSE

We sought to investigate the association of meibomian gland morphology with lid margin abnormalities in patients with meibomian gland dysfunction.

METHODS

This retrospective study included 368 eyes of 184 patients. Meibography was used to evaluate meibomian gland (MG) morphological features, such as dropout, distortion, thickened ratio and thinned ratio. Lid margin photography was used to evaluate lid margin abnormalities including orifice plugging, vascularity, irregularity and thickening. The association between MG morphological features and lid margin abnormalities was analyzed using a mixed linear model.

RESULTS

The study found a positive correlation between plugging of gland orifices grade and MG dropout grade in both the upper lids (B = 0.40, p = 0.007) and the lower lids (B = 0.55, p = 0.001). Plugging of gland orifices grade was also positively correlated to MG distortion grade in the upper lids (B = 0.75, p = 0.006). In the upper lids, MG thickened ratio increased first (B = 0.21, p = 0.003) and then decreased (B = - 0.14, p = 0.010) with a higher lid margin thickening grade. MG thinned ratio was negatively correlated with lid margin thickening (B = - 0.14, p = 0.002, B = - 0.13, p = 0.007). MG distortion grade decreased with lid margin thickening (B = - 0.61, p = 0.012).

CONCLUSION

Orifice plugging was correlated to meibomian gland distortion and dropout. Lid margin thickening was associated with meibomian gland thickened ratio, thinned ratio, and distortion. The study also suggested that distorted and thinned glands may be transitional phases between thickened glands and glands dropout.

Comparison of clinical outcomes between intense pulsed light therapy using two different filters in meibomian gland dysfunction: prospective randomized study

Our study compared treatment efficacy between cut-off and notch filters in intense pulsed light (IPL) therapy for meibomian gland dysfunction (MGD) through a prospective, randomized paired-eye trial. Additionally, the efficacy of IPL treatment alone was investigated by restricting other conventional treatments. One eye was randomly selected for an acne filter and the other for a 590-nm filter. Identical four regimens of IPL treatments were administered. The tear break-up time (TBUT), Oxford scale, Sjögren's International Clinical Collaborative Alliance (SICCA) staining score, tear matrix metalloproteinase-9 (MMP-9) expression, tear osmolarity, and Ocular Surface Disease Index (OSDI) questionnaires were evaluated before and after IPL. Meibomian gland (MG) parameters were measured. When combining the results from both filters, the TBUT, SICCA staining score, OSDI score, and upper and lower lid meibum expressibility were improved after IPL. No significant differences were found between the two filters in the TBUT, Oxford scale, SICCA staining score, MMP-9 expression, tear osmolarity, and MG parameters. Although not significant, the acne filter showed better treatment efficacy than that in the 590-nm filter. IPL alone is efficacious in terms of ocular surface parameters, MG function, and subjective symptoms. Regarding filter selection, both acne and 590-nm filters are promising options for MGD treatment.

The inhibition of p38 MAPK blocked inflammation to restore the functions of rat meibomian gland epithelial cells

Meibomian glands (MGs) are vital for ocular surface health. However, the roles of inflammation in the progression of meibomian gland dysfunction (MGD) are largely unknown. In this study, the roles of the inflammation factor interleukin-1β (IL-1β) via the p38 mitogen-activated protein kinases (MAPK) signaling pathway on rat meibomian gland epithelial cells (RMGECs) were explored. Eyelids from adult rat mice at 2 months and 2 years of age were stained with specific antibodies against IL-1β to identify inflammation levels. RMGECs were exposed to IL-1β and/or SB203580, a specific inhibitor of p38 MAPK signaling pathway, for 3 days. Cell proliferation, keratinization, lipid accumulation, and matrix metalloproteinases 9 (MMP9) expression were evaluated by MTT assay, polymerase chain reaction (PCR), immunofluorescence staining, apoptosis assay, lipid staining, and Western blot analyses. We found that IL-1β was significantly higher in the terminal ducts of MGs in rats with age-related MGD than in young rats. IL-1β inhibited cell proliferation, suppressed lipid accumulation and peroxisome proliferator activator receptor γ (PPARγ) expression, and promoted apoptosis while activating the p38 MAPK signaling pathway. Cytokeratin 1 (CK1), a marker for complete keratinization, and MMP9 in RMGECs were also up-regulated by IL-1β. SB203580 effectively diminished the effects of IL-1β on differentiation, keratinization, and MMP9 expression by blocking IL-1β-induced p38 MAPK activation, although it also inhibited cell proliferation. The inhibition of the p38 MAPK signaling pathway blocked IL-1β-induced differentiation reduction, hyperkeratinization, and MMP9 overexpression of RMGECs, which provides a potential therapy for MGD.

Precision Medicines for Retinal Lipid Metabolism-Related Pathologies

Oxidation of lipids and lipoproteins contributes to inflammation processes that promote the development of eye diseases. This is a consequence of metabolism dysregulation; for instance, that of the dysfunctional peroxisomal lipid metabolism. Dysfunction of lipid peroxidation is a critical factor in oxidative stress that causes ROS-induced cell damage. Targeting the lipid metabolism to treat ocular diseases is an interesting and effective approach that is now being considered. Indeed, among ocular structures, retina is a fundamental tissue that shows high metabolism. Lipids and glucose are fuel substrates for photoreceptor mitochondria; therefore, retina is rich in lipids, especially phospholipids and cholesterol. The imbalance in cholesterol homeostasis and lipid accumulation in the human Bruch's membrane are processes related to ocular diseases, such as AMD. In fact, preclinical tests are being performed in mice models with AMD, making this area a promising field. Nanotechnology, on the other hand, offers the opportunity to develop site-specific drug delivery systems to ocular tissues for the treatment of eye diseases. Specially, biodegradable nanoparticles constitute an interesting approach to treating metabolic eye-related pathologies. Among several drug delivery systems, lipid nanoparticles show attractive properties, e.g., no toxicological risk, easy scale-up and increased bioavailability of the loaded active compounds. This review analyses the mechanisms involved in ocular dyslipidemia, as well as their ocular manifestations. Moreover, active compounds as well as drug delivery systems which aim to target retinal lipid metabolism-related diseases are thoroughly discussed.

Features and influences on the normal tear evaporation rate

Tear evaporation is a normal physiological phenomenon that has an important role in regulating blink activity and tear production. An altered tear evaporation rate (TER) is a defining characteristic of evaporative dry eye disease (DED), and the measurement of tear evaporation is a useful clinical test for diagnosis. Reported values for a normal TER cover a broad range, which may be due to the influence of ocular, environmental, and systemic factors. For improved disease diagnosis, a fuller understanding of the normal TER range is essential. This paper reports on a literature review of the current knowledge of these normal influences on TER.

TFOS lifestyle: Impact of societal challenges on the ocular surface

Societal factors associated with ocular surface diseases were mapped using a framework to characterize the relationship between the individual, their health and environment. The impact of the COVID-19 pandemic and mitigating factors on ocular surface diseases were considered in a systematic review. Age and sex effects were generally well-characterized for inflammatory, infectious, autoimmune and trauma-related conditions. Sex and gender, through biological, socio-economic, and cultural factors impact the prevalence and severity of disease, access to, and use of, care. Genetic factors, race, smoking and co-morbidities are generally well characterized, with interdependencies with geographical, employment and socioeconomic factors. Living and working conditions include employment, education, water and sanitation, poverty and socioeconomic class. Employment type and hobbies are associated with eye trauma and burns. Regional, global socio-economic, cultural and environmental conditions, include remoteness, geography, seasonality, availability of and access to services. Violence associated with war, acid attacks and domestic violence are associated with traumatic injuries. The impacts of conflict, pandemic and climate are exacerbated by decreased food security, access to health services and workers. Digital technology can impact diseases through physical and mental health effects and access to health information and services. The COVID-19 pandemic and related mitigating strategies are mostly associated with an increased risk of developing new or worsening existing ocular surface diseases. Societal factors impact the type and severity of ocular surface diseases, although there is considerable interdependence between factors. The overlay of the digital environment, natural disasters, conflict and the pandemic have modified access to services in some regions.

Hot towels: The bedrock of Meibomian gland dysfunction treatment - A review

BACKGROUND

Meibomian gland dysfunction (MGD) reduces quality-of-life and hinders work productivity of millions of patients, with high direct and indirect societal costs. Thickened meibum obstructs the glands and disrupts ocular surface health. Heating the eyelids to soften and express meibum from the glands can be beneficial. The most accessible method for eyelid warming uses heated, wet towels. However, the efficacy of this treatment is reliant on the methodology, and evidence-based best-practice recommendations are needed.

PURPOSE

To evaluate the literature on hot towels in MGD treatment and recommend a best-practice protocol for future research and patient treatment.

METHODS

Studies were identified through PubMed on the May 28, 2021, with the search terms: (warm* OR heat* OR thermal* OR towel OR wet towel) AND (meibomian OR MGD OR eyelid OR "dry eye" OR DED). All relevant original articles with English full-text were included.

RESULTS

The search yielded 903 results, of which 22 met the inclusion criteria. Across studies, hot towels were found to be effective at reducing ocular symptoms. However, without reheating, the temperature quickly fell below the therapeutic range, which was deemed to be between 40 °C and 47 °C. Towels heated to around 45 °C and reheated every-two minutes were most effective at increasing eyelid temperature, comparable or better than several commercially available eyelid warming devices. No adverse effects were reported in the studies.

CONCLUSION

Hot towel treatment effectively warms the eyelids and reduces ocular symptoms, but must be standardized, and towels reheated to achieve maximum benefit. Future research should assess patient satisfaction with different hot towel treatment methods that reheat or replace the towel at least every-two minutes, to establish which methods yield the greatest compliance. Guidelines or clinical recommendations that do not mention the need for regular reheating during hot towel compress treatment should be updated to include this.

Primary cilia control cellular patterning of Meibomian glands during morphogenesis but not lipid composition

Meibomian glands (MGs) are modified sebaceous glands producing the tear film's lipids. Despite their critical role in maintaining clear vision, the mechanisms underlying MG morphogenesis in development and disease remain obscure. Cilia-mediate signals are critical for the development of skin adnexa, including sebaceous glands. Thus, we investigated the role of cilia in MG morphogenesis during development. Most cells were ciliated during early MG development, followed by cilia disassembly during differentiation. In mature glands, ciliated cells were primarily restricted to the basal layer of the proximal gland central duct. Cilia ablation in keratine14-expressing tissue disrupted the accumulation of proliferative cells at the distal tip but did not affect the overall rate of proliferation or apoptosis. Moreover, impaired cellular patterning during elongation resulted in hypertrophy of mature MGs with increased meibum volume without altering its lipid composition. Thus, cilia signaling networks provide a new platform to design therapeutic treatments for MG dysfunction.

High-fat intake reshapes the circadian transcriptome profile and metabolism in murine meibomian glands

Background

Nutritional and food components reshape the peripheral clock and metabolism. However, whether food challenges affect the circadian clock and metabolism of meibomian glands (MGs) has not been fully explored. This study was designed to analyze alterations in the rhythmic transcriptome and metabolism of MGs of murine fed a balanced diet or a high-fat diet (HFD).

Methods

Male C57BL/6J mice were maintained on a 12/12 h light/dark cycle and fed ad libitum on normal chow (NC) or HFD for 4 weeks. MGs were collected from sacrificed animals at 3-h intervals throughout a 24-h circadian cycle. The circadian transcriptome of MGs was analyzed via bioinformatics approaches using high-throughput RNA sequencing (RNA-seq). In addition, circadian oscillations of lipid components in MGs were analyzed.

Results

Meibomian glands displayed robust transcriptome rhythmicity. HFD feeding significantly altered the circadian transcriptome profile of MGs—including composition and phase—and spatiotemporally affected the enriched signaling pathways. In addition, HFD feeding significantly altered the normal rhythmic oscillations of lipid components in MGs.

Conclusion

Our data show that HFD significantly affects MGs’ rhythmicity, which reveals a high sensitivity of MGs’ clocks to lipid composition in food.

A Comparative Study of Two Imaging Techniques of Meibomian Glands

In the present study, two different meibographers, Oculus Keratograph 5M (K5M) that uses 840 nm infrared light and the Visible Light Non-Contact Meibographer (VLNCM) that uses 610 nm visible light have been used to obtain meibography images from normal and Meibomian Gland Dysfunction (MGD) population. The main objective has been to validate and demonstrate that the use of visible light is useful for observation and quantification of MG in clinical practice. Twenty participants were enrolled in this prospective study. The upper eyelids of one randomly chosen eye were used to obtain results. Forty images were captured and analysed. Three specialized observers were recruited to grade images using Pult and Riede Pult 5-degree scale, in two different sessions. Intra-observer agreement between sessions for both devices was shown. Inter-observer variability analysis showed discrepancy between meiboscores obtained from observers with K5M (p-value < 0.05), except for session 2 in the pathology group, while no statistical difference was found with VLNCM. Repeatability analysis found no statistically significant differences between sessions. Correlation between meibographers showed no statistically significant difference and a moderate correlation coefficient between meiboscores graded with the two devices. The current study suggests that VLNCM can allow MG to be properly visualized and classified in the upper eyelids.

Biophysical profiling of synthetic ultra-long tear film lipids

The tear film lipid layer (TFLL) is a unique biological membrane of importance to the maintenance of ocular surface health. The underlying factors at play, e.g. the ability to retard evaporation and offer protection from the environment, are all closely connected to the properties of individual lipid components and their interplay. The TFLL contains unique ultra-long polar lipid species such as O-acyl-ω-hydroxy fatty acids, type I-St diesters and type II diesters, which are considered important for its proper function. Herein, we have synthesized model compounds from these categories and studied their biophysical and surface rheological properties at the aqueous interface. Altogether, we provide insights on the distinct biophysical profiles of these lipid classes and discuss how their interplay may affect the structure and function of the TFLL.

The Approach of Intense Pulsed Light Treatment in Patients with Different Severities of Meibomian Gland Dysfunction

PURPOSE

To make appropriate therapeutic decisions of intense pulsed light (IPL) for meibomian gland dysfunction (MGD) patients.

METHODS

Sixty patients with MGD stage 2-3 were enrolled in IPL Group1 and Self-hygiene Group; 110 patients with MGD stage 3-4 were included in IPL + MGX Group and IPL Group2. Patients in IPL groups received IPL treatment once a month for three times. Meibomian gland expression (MGX) was combined with IPL treatment in IPL + MGX Group. Meibomian gland (MG) functions, MGD stage, associated ocular-surface indexes, and response rate were evaluated.

RESULTS

Population characteristics and clinical conditions were comparable between groups. In patients with MGD stage 2-3, both IPL Group1 and Self-hygiene Group improved in MG functions, ocular surface disease index (OSDI) and tear break-up time (TBUT). No statistical difference was found in improvements. Posttreatment response rate was 64.3-66.7% in two groups. In patients with MGD stage 3-4, IPL + MGX Group achieved better improvements in MG expressibility and higher response rate (75.5%) than IPL Group2 (63.3%). Referring to IPL treatment, no statistical difference in MG functions and OSDI improvements was found among MGD patients with different ages, genders, and IPL energy exposure. Patients with higher Fitzpatrick scale improved more in MG expressibility.

CONCLUSION

Self-eyelid hygiene is cost-effective for milder MGD stages. Combining MGX with IPL is necessary in more severe stages. Adult patients with all age and different genders can benefit from IPL treatment. Patients with darker skin can benefit more in expressiblity.

Association between Dyslipidemia and Meibomian Gland Dysfunction: A Systematic Review and Meta-Analysis

PURPOSE

This study aimed to use meta-analysis to estimate the association between dyslipidemia and meibomian gland dysfunction.

METHODS

The following databases were searched: PubMed, Google Scholar, and Scopus. Case-control and cohort studies assessing the association between dyslipidemia and meibomian gland dysfunction were included. The association was assessed using odds ratios. Heterogeneity between studies was assessed with the χ2 statistic and degree of inconsistency. The quality of studies was assessed using the Newcastle-Ottawa Scale. The systematic review was registered on PROSPERO (ID: CRD42022347982).

RESULTS

The systematic review included three case-control and two cohort studies. The odds of hypercholesterolemia and hypertriglyceridemia in meibomian gland dysfunction were 5.45 (95% confidence interval [CI], 1.65 to 17.95) and 3.28 (95% CI, 1.25 to 8.62), respectively. The odds of elevated serum low-density lipoprotein and reduced high-density lipoprotein in meibomian gland dysfunction were 2.72 (95% CI, 1.24 to 5.98) and 1.15 (95% CI, 0.74 to 1.79), respectively. The current study's limitation is that the effects of sex, age, and meibomian gland dysfunction severity on the association between dyslipidemia and meibomian gland dysfunction were not assessed.

CONCLUSIONS

The current study suggests a significant association between dyslipidemia and meibomian gland dysfunction. This finding suggests that meibomian gland dysfunction diagnosis may call for dyslipidemia screening.

Is Corneal Subbasal Nerve Loss Associated With Meibomian Gland Loss in Inactive Mild and Moderate-to-Severe Graves' Ophthalmopathy?

PURPOSE

To evaluate meibomian gland and subbasal nerve plexus parameters in Graves' Ophthalmopathy (GO) and association of meibomian gland loss with corneal subbasal nerve plexus loss.

METHODS

Fifty-two eyes of 52 mild and moderate-to-severe GO patients and 32 eyes of 32 healthy controls were enrolled. The meibomian gland dropout area (MGDA) and meibography scores were evaluated using noncontact meibography. In vivo confocal microscopy of corneal subbasal nerve plexus were conducted. ACCMetrics was used to obtain corneal parameters.

RESULTS

Compared with healthy subjects, GO patients had worse upper and lower eyelid MGDA ( p < 0.001, for all) and upper, lower and total meibography scores ( p < 0.001, p = 0.001, and p < 0.001, respectively). Eyelid margin scores were worse in the GO group ( p < 0.001) and showed correlation with all noncontact meibography parameters ( p < 0.001 for all). All corneal subbasal nerve parameters were significantly lower in the GO group compared with the controls ( p < 0.05 for all). Subbasal nerve parameters of GO patients did not reveal a correlation with MGDA and meibography scores but showed correlations with ocular surface disease index score and Schirmer I test (r = -0.304; p = 0.042 and r = 0.336; p = 0.021, respectively).

CONCLUSION

Meibomian gland and corneal nerve loss could be observed even in the inactive phase and mild GO. The lack of a correlation between meibomian gland loss and subbasal nerve loss suggests that meibomian gland loss is not a significant additional component in the pathogenesis of subbasal nerve damage in GO. Furthermore, our study revealed new evidence regarding the use of eyelid margin score to represent meibomian gland loss in GO.

Dry Eye Disease Associated with Meibomian Gland Dysfunction: Focus on Tear Film Characteristics and the Therapeutic Landscape

Meibomian gland dysfunction (MGD) is highly prevalent and is the leading cause of evaporative dry eye disease (DED). MGD is characterized by a reduction in meibum secretion and/or a change in meibum composition that results in the disruption of the tear film lipid layer and an increase in the tear film evaporation rate. Excessive evaporation causes tear film instability, desiccation, tear hyperosmolarity, inflammation, and apoptosis of ocular surface cells, resulting in a continuous cycle of DED. The primary treatment goal for DED associated with MGD is to restore the tear film lipid layer and decrease evaporation, thereby reducing ocular signs and symptoms. The management of MGD includes home care options (eyelid hygiene, warming eye masks, ocular lubricants) and office-based treatments (manual expression, microblepharoexfoliation, thermal pulsation, intense pulsed light, intraductal probing). Topical ophthalmic prescription medications attempt to alter various factors that may contribute to DED (e.g., inflammation, bacterial growth, inadequate tear production). In this review, clinical evidence regarding available treatments and emerging therapies from randomized studies in patients with DED associated with MGD is summarized. Although some treatment modalities have been evaluated specifically for DED patients with MGD, large-scale randomized controlled trials are needed to confirm efficacy and safety in this patient population. Currently, there are no approved prescription pharmacologic treatments specifically indicated for DED associated with MGD, and those medications approved for the treatment of DED do not target the key driver of the disease (i.e., excessive evaporation). NOV03 (perfluorohexyloctane; under review with the US Food and Drug Administration) is the most advanced emerging therapy for DED associated with MGD and has demonstrated statistically significant improvements in both signs and symptoms in randomized controlled trials. Development of novel pharmacotherapies will improve therapeutic options and allow for a more individualized approach for patients with DED associated with MGD.

Evaluation of corneal ulcer type, skull conformation, and other risk factors in dogs: A retrospective study of 347 cases

Objective

To investigate the incidence of corneal ulceration (CU) and establish risk factors for dogs referred to an academic referral hospital in Ontario, Canada.

Animals

Dogs (N = 1101).

Procedure

Type of CU, number of CU diagnoses, breed, skull conformation, weight, sex, neuter status, age, and comorbidities were analyzed for simple CU, spontaneous chronic corneal epithelial defects (SCCEDs), and complex CU. Complex ulcers were subdivided into deep, presence of keratomalacia, descemetoceles, and corneal lacerations and foreign bodies (CLFB).

Results

The inclusion criteria were met by 347 dogs and 754 served as a control population of non-corneal ulceration (NCU) cases. Complex ulcers predominated (n = 134; 38.5%), including deep (n = 41; 11.8%), with keratomalacia (n = 20; 5.7%), descemetocele (n = 59; 17.0%), and CLFB (n = 14; 4.0%). Shih tzus were most predominant for every ulcer type, except for boxers for SCCEDs. Brachycephalic breeds have 2.757 greater odds (P < 0.0001) of presenting for CU, and 2.695 greater odds (P < 0.0001) of having a complex CU. Each 1 kg decrease in body weight increased odds of CU diagnosis by 1.3%. Yearly increase in age augmented the odds of CU diagnosis by 8.9% (P < 0.0001); older dogs were more likely to have SCCEDs (P = 0.0040) and keratomalacia (P = 0.0257). Comorbidities increased odds of repeat CU diagnosis (P = 0.0024). Dogs with diabetes mellitus (P = 0.0318) had higher odds of SCCEDs.

Conclusion

Skull conformation, age, body weight, and comorbidities were identified risk factors for CU.

Clinical relevance

Knowledge of risk factors will help veterinarians triage at risk demographics.

The Importance of Identifying Meibomian Gland Inversion in Patients With Floppy Eyelid Syndrome

BACKGROUND

Floppy eyelid syndrome (FES) is a common and underdiagnosed condition characterized by eyelid hyperlaxity with reactive palpebral conjunctivitis that can cause ocular irritation. It may be associated with meibomian gland dysfunction (MGD) and secondary tarsal curling, resulting in upper eyelid meibomian gland inversion (MGI) in the absence of obvious marginal entropion.

PURPOSE

To highlight the possible significance of MGI in patients with FES and report findings and outcomes in patients with concomitant MGI and FES undergoing correction of MGI with or without upper eyelid horizontal tightening.

METHODS

Retrospective, 5-year, noncomparative, single-center study of patients with FES and MGI, treated with MGI correction, with or without upper eyelid horizontal tightening, under the supervision of a single surgeon. Preoperative symptoms, surgical outcomes, complication rates, and postoperative symptoms were recorded.

RESULTS

A total of 13 eyes of 9 patients were treated with MGI surgery over the study period. Seven were male. Mean age at the surgery was 63 (range 42-81) years. Two OSs, 3 ODs, and 4 OUs were treated. All patients were "cotton-tip test" positive, and 77% (10/13) had MGI-related superior corneal fluorescein staining. Three patients (33%) had previous standard tightening procedures with recurrence of symptoms within 5 to 24 (mean 16) months. Repeat horizontal tightening had been considered in all these cases before referral to our unit. Mean follow-up was 20 months. Eight patients (88.9%) had improvement of symptoms (n = 3, full resolution; n = 5, partial resolution). All patients demonstrated restoration of the normal anatomical position of the meibomian glands. Superior punctate staining resolved in all eyes.

CONCLUSION

This study provides a proof of concept that upper eyelid MGI can be present and symptomatic in patients with FES. It may help explain cases where symptoms persist or recur early following standard upper eyelid horizontal tightening. Where superior corneal punctate staining and a positive cotton-tip test exist, surgical correction of MGI, alongside horizontal tightening, may provide better, and longer-lasting symptomatic relief. This study provides evidence for the need for a prospective study to evaluate the contribution of MGI in patients with FES.

Repeatability and reproducibility of Cobra HD fundus camera meibography in young adults with and without symptoms of dry eye

PURPOSE

The inter-session repeatability (ISR), inter-examiner reproducibility (IER) and within-subject variability (WSV) of the Cobra HD fundus camera meibographer were examined in participants with and without dry eye symptoms.

METHODS

Symptoms were determined based on Ocular Surface Disease Index scores (≥13 being considered symptomatic), and subgroups were compared using the Mann-Whitney U-test. Images of meibomian glands (MGs) from the upper and lower right eyelids were captured by two examiners on the same day (S1) to determine IER. One examiner repeated the measurements on a second day (S2) to obtain the ISR. ISR, IER and WSV were calculated using Friedman, correlation tests and Bland and Altman analyses with mean differences (md) and 95% confidence intervals (CIs), within-subject standard deviations (Sw) and intra-class correlation coefficients (ICC).

RESULTS

The ISR experiment included 72 participants (mean age: 23 ± 5 years, range: 19-43, 36 symptomatic). Mean MG loss of the upper (S1: 13.5 ± 9.5%, S2: 12.8 ± 8.5%) and lower eyelids (S1: 7.5 ± 6.9%, S2: 7.3 ± 6.3%) was not significantly different between sessions for all participants, symptomatic and asymptomatic subgroups for both eyelids. The ISR Sw for the upper and lower eyelids was 1.3% and 1.0%; md was 0.7 ± 3.5% (CI:-6.25% to 7.62%) and 0.1 ± 2.1% (CI: -3.94% to 4.17%), respectively. The IER experiment included 74 participants (mean age: 23 ± 5 years, range: 19-43, 37 symptomatic). Mean MG loss of the upper (Examiner 1: 12.7 ± 8.2%, Examiner 2: 13.1 ± 8.0%) and lower eyelids (Examiner 1: 7.0 ± 6.2%, Examiner 2: 7.4 ± 6.2%) was not significantly different between examiners for all participants, symptomatic and asymptomatic subgroups for both eyelids. The IER ICC values were >0.86 for all conditions, Sw was 1.3% and 1.2%, with a md of -0.4 ± 3.2% (CI: -6.65% to 5.90%) and -0.4 ± 2.9% (CI: -6.15% to 5.31%), respectively. The WSV Sw values were <1.4%, and ICC values were >0.89 for both eyelids, examiners and experimental sessions.

CONCLUSIONS

The Cobra HD fundus camera demonstrates good repeatability, reproducibility and low WSV, and is a reliable clinical instrument for meibography.

Ductal Hyperkeratinization and Acinar Renewal Abnormality: New Concepts on Pathogenesis of Meibomian Gland Dysfunction

Meibomian gland dysfunction (MGD) is a functional and morphological disorder of the meibomian glands which results in qualitative or quantitative alteration in meibum secretion and is the major cause of evaporative dry eye (EDE). EDE is often characterized by tear film instability, increased evaporation, hyperosmolarity, inflammation, and ocular surface disorder. The precise pathogenesis of MGD remains elusive. It has been widely considered that MGD develops as a result of ductal epithelial hyperkeratinization, which obstructs the meibomian orifice, halts meibum secretion, and causes secondary acinar atrophy and gland dropout. Abnormal self-renewal and differentiation of the acinar cells also play a significant role in MGD. This review summarizes the latest research findings regarding the possible pathogenesis of MGD and provides further treatment strategies for MGD-EDE patients.

Dry eye and dry skin - is there a connection?

AIM

To enquire whether patients with dry eye symptoms also report dry skin, whether their perception could be corroborated with objective measurement, and whether dry eye disease might be suspected based on patients' complaints.

METHODS

This cross-sectional study included 50 subjects, 25 with and 25 without dry eye symptoms. Schein questionnaire was used to determine the severity of dry eye symptoms. Ocular signs were assessed by monitoring conjunctival hyperemia, ocular surface staining, meibomian gland expression, tear film lipid layer thickness, tear break-up time, lid parallel conjunctival folds, Schirmer test, and meibometry. Skin dryness was assessed by noting patients' self-perception of their facial skin dryness and measured by sebumeter.

RESULTS

Subjects without dry eye symptoms had self-reported oilier facial skin than those with dry eye symptoms (p < .001). Sebumetry scores measured on the forehead and cheek were significantly higher in subjects without dry eye symptoms than dry eye subjects (p = .003). After adjustment for age and gender in a logistic regression analysis, dry eye was independently and significantly associated with dry skin (AOR 0.69, p = .040), higher LIPCOF score of both eyes (AOR 2.28, p = .028), lower sebumetry score of the forehead (AOR 0.98, p = .041) and cheek (AOR 0.98, p = .041), and shorter TBUT score after gland expression (AOR 0.90, p = .018).

CONCLUSION

This study showed that ocular dryness was subjectively and objectively positively correlated to facial skin dryness. Patients reliably described their skin condition. People with dry facial skin also had drier eyes.

Assessment of meibomian gland drop-out and visibility through a new quantitative method in scleral lens wearers: A one-year follow-up study

OBJECTIVES

To validate a previously developed algorithm based on the visibility of meibomian gland images obtained with Cobra fundus camera and to assess the changes in meibomian glands in scleral lens wearers over one year of lens wear.

METHODS

Infrared meibography was obtained from the upper eyelid using the Cobra fundus camera in forty-three volunteers (34.2 ± 10.1 years). Meibographies were classified into 3 groups: Group 1 = good subjective gland visibility and gland drop-out < 1/3 of the total area; Group 2 = low visibility and gland drop-out < 1/3; and Group 3 = low visibility and gland drop-out > 1/3. Meibomian gland visibility metrics were then calculated using the developed algorithm from the pixel intensity values of meibographies. Repeatability of new metrics and their correlations with gland drop-out were assessed. Meibographies and ocular symptoms were also assessed after 1 year of scleral lens wear in 29 subjects.

RESULTS

Gland drop-out percentage was not statistically different between groups 1 and 2 (p = 0.464). Nevertheless, group 1 showed higher grey pixel intensity values than the other groups. Statistically significant correlations were found between gland visibility metrics and gland drop-out percentage. Repeatability was acceptable for all metrics, coefficient of variation achieving values between 0.52 and 3.18. While ocular symptoms decreased with scleral lens wear (p < 0.001), no statistically significant differences were found in gland drop-out percentage (p = 0.157) and gland visibility metrics (p > 0.217).

CONCLUSIONS

The proposed method can assess meibomian gland visibility in an objective and repeatable way. Scleral lens wear appears to not adversely affect meibomian gland drop-out and visibility while might improve dry eye symptoms after one year of lens wear. These preliminary results should be confirmed with a control group.

Serial Sessions of a Novel Low-Level Light Therapy Device for Home Treatment of Dry Eye Disease

INTRODUCTION

This study aimed to evaluate the changes that a recently developed at-home device using low-level light therapy (LLLT) produced in signs and symptoms of patients with dry eye disease (DED) owing to meibomian gland dysfunction (MGD).

METHODS

In this prospective study, patients with DED owing to MGD not successfully responding to first-line therapy (tear substitutes and eye lid hygiene) were treated with four serial sessions (every other day) of mask based on LLLT technology and dedicated for home use (my-mask^®, Espansione Marketing S.p.A., Bologna, Italy). Non-invasive ocular surface examination was carried out by means of Keratograph 5M (Oculus, Wetzlar, Germany) before and after four mask sessions for the evaluation of (i) tear meniscus height (TMH); (ii) first and average non-invasive Keratograph breakup time (NIKBUT); (iii) meibomian gland loss (MGL). Ocular Surface Disease Index (OSDI) questionnaire was used to assess ocular discomfort symptoms.

RESULTS

Overall, 17 patients (3 male, 14 female; mean age 61.47 ± 11.93 years) were enrolled and all of them regularly completed the entire cycle of four sessions without reporting any adverse event. The mean values of NIKBUT first and NIKBUT average increased significantly after treatment (from 5.29 ± 2.60 at T0 to 9.04 ± 3.49 s at T1 [P = 0.001] and from 9.40 ± 3.81 to 11.28 ± 2.81 s [P = 0.017]); in parallel, the mean value of TMH increased significantly from 0.27 ± 0.06 to 0.32 ± 0.09 mm (P = 0.029). Conversely, there were not statistically significant differences for MGL (P = 0.346). In addition, the mean value of OSDI score decreased after treatment (from 32.00 ± 7.96 at T0 to 20.71 ± 8.03 at T1; P < 0.001).

CONCLUSIONS

One week of serial sessions of a newly developed LLLT device for home use significantly improved tear film production and stability along with ocular discomfort symptoms in patients with DED owing to MGD. These findings open up a new scenario for patients with MGD who can enjoy the unique benefits of LLLT at home.

Morphological variants of meibomian glands: correlation of meibography features with histopathology findings

PURPOSE

This study describes the histopathological features of different morphological variants of human meibomian glands (MGs) seen on infrared imaging.

METHODS

Tarsal plates dissected from seven cadaveric upper eyelids were imaged using infrared meibography, and then studied histopathologically using H&E, peroxisome proliferator-activated receptor gamma (PPARγ, meibocyte differentiation marker) and Ki-67 (cellular proliferation marker) antibody staining. The different morphological characteristics (varying size and shape) of MGs on meibography were correlated with histopathology findings using image analysis software.

RESULTS

Of the total 127 glands, the morphological variants observed on meibography based on size were: normal (n=62), short (n=18), severely short (n=6) and dropout (n=12) glands, and on shape were: hooked (n=2), tortuous (n=5), overlapping (n=1), thick (n=15) and fluffy (n=6) glands. Short, hooked, tortuous and overlapping glands had similar acinar and ductal histology as seen in normal glands whereas thick, and fluffy glands had increased acinar diameter. All glands except the severely short type demonstrated normal signs of holocrine secretory activity and normal nuclear and cytoplasmic PPARγ expression. Severely short glands had nil while short glands had reduced Ki-67 proliferation index (3%±1%) as compared with normal and other variants (8%±5.2%). Gland dropout areas showed no evidence of any glandular tissue on histology.

CONCLUSION

Hooked, tortuous and overlapping glands had completely normal glandular histology, whereas severely short glands showed atrophic changes with loss of meibocyte differentiation and cellular proliferation. Dropout areas showed total loss of glandular elements. Further studies are needed to validate and to explore the clinical implications of these findings.