Meibum Lipidomic Analysis in Evaporative Dry Eye Subjects.

Meibomian Glands (MG) are sebaceous glands responsible for the production of meibum, the main component of the Tear Film Lipid Layer (TFLL). The TFLL facilitates the spread of the tear film over the ocular surface, provides stability and reduces tear evaporation. Alterations in meibum composition lead to different ocular alterations like Meibomian Gland Dysfunction (MGD) and subsequent Evaporative Dry Eye (EDE). The aim of the present study was to investigate the composition and abundance of meibum lipids and their relationship with eyelid margin abnormalities, lipid layer patterns and MG status. The study utilizes a lipidomic approach to identify and quantify lipids in meibum samples using an Elute UHPLC system. This system considered all four dimensions (mass/charge, retention time, ion mobility and intensity) to provide the accurate identification of lipid species. Samples were categorized as healthy or low/no signs of alteration (group 1) or severe signs of alteration or EDE/MGD (group 2). The current investigation found differences in Variable Importance in Projection lipid abundance between both groups for the MGD signs studied. Changes in meibum composition occur and are related to higher scores in eyelid margin hyperaemia, eyelid margin irregularity, MG orifice plugging, MG loss and lipid layer pattern.

Ocular complications in adults with psoriasis: a cross-sectional study in a referral center in Brazil.

PURPOSE: There is limited literature on the ocular manifestations in patients with psoriasis. Therefore, this study aimed to identify the prevalence of and factors associated with ocular manifestations in adults with psoriasis. METHODS: This cross-sectional study included Brazilian adults with psoriasis. The dermatological evaluation included diagnosis, clinical form, Psoriasis Area and Severity Index (PASI) measurement, and location of the lesions. Patients underwent a full ophthalmological examination, including the Schirmer I test, Rose Bengala staining, and tear breakup time tests. The results were analyzed using chi-square and Pearson's linear correlation tests. RESULTS: Of the 130 patients assessed, 118 (90.8%) exhibited ocular abnormalities, with meibomian gland dysfunction (MGD) being the most prevalent (59.2%), followed by dry eye disease (DED) (56.2%). A significant correlation was observed between MGD and PASI (p = 0.05), and between MGD and certain treatment modalities. DED was significantly associated with PASI (p < 0.05). Concurrent use of acitretin was identified as an independent predictor of MGD (odds ratio [OR] = 3.5, p < 0.05), whereas PASI was a protective factor against DED (OR = 0.39, p < 0.01). CONCLUSION: Given the high prevalence of eye disease among individuals with psoriasis, routine ophthalmological assessments are recommended to prevent possible ocular complications.

Intense pulsed light therapy for ocular surface diseases.

Intense pulsed light (IPL) is a non-laser, high-intensity light source that has been shown to play a valuable role in dermatology and has been adopted in ophthalmology for treating meibomian gland dysfunction (MGD). In this review, we discuss the mechanism of action of IPL, including its benefits in ophthalmology. IPL therapy has been shown to improve tear film stability, meibomian gland (MG) function, and subjective symptoms of ocular dryness in MGD patients. Moreover, emerging evidence suggests that IPL therapy is beneficial for other ocular surface diseases, such as blepharitis and chalazia. Hence, it can be inferred that IPL has potential as a therapeutic modality in future applications. Large clinical and experimental trials are needed to exploit the full potential of IPL as a treatment for recurrent chalazia, Sjögren's syndrome, and other causes of dry eye disease (DED). This paper reviews the published literature related to the application of IPL for treating ocular surface diseases.

Thermosensitive TRP Channels Are Functionally Expressed and Influence the Lipogenesis in Human Meibomian Gland Cells.

While the involvement of thermosensitive transient receptor potential channels (TRPs) in dry eye disease (DED) has been known for years, their expression in the meibomian gland (MG) has never been investigated. This study aims to show their expression and involvement in the lipogenesis of the MG, providing a possible new drug target in the treatment of DED. Our RT-PCR, Western blot and immunofluorescence analysis showed the expression of TRPV1, TRPV3, TRPV4 and TRPM8 in the MG at the gene and the protein level. RT-PCR also showed gene expression of TRPV2 but not TRPA1. Calcium imaging and planar patch-clamping performed on an immortalized human meibomian gland epithelial cell line (hMGECs) demonstrated increasing whole-cell currents after the application of capsaicin (TRPV1) or icilin (TRPM8). Decreasing whole-cell currents could be registered after the application of AMG9810 (TRPV1) or AMTB (TRPM8). Oil red O staining on hMGECs showed an increase in lipid expression after TRPV1 activation and a decrease after TRPM8 activation. We conclude that thermo-TRPs are expressed at the gene and the protein level in MGs. Moreover, TRPV1 and TRPM8's functional expression and their contribution to their lipid expression could be demonstrated. Therefore, TRPs are potential drug targets and their clinical relevance in the therapy of meibomian gland dysfunction requires further investigation.

Red filter meibography by smartphones in patients with meibomian gland dysfunction: a validity and reliability study.

OBJECTIVE: The objective of this study is to determine the validity and reliability of the red filter meibography by smartphone compared with infrared in assessing meibomian gland drop-out. METHODS AND ANALYSIS: An analytical cross-sectional study was done with a total of 35 subjects (68 eyes) with suspected MGD based on symptoms and lid morphological abnormalities. Meibomian glands were photographed using two smartphones (Samsung S9 and iPhone XR) on a slit-lamp with added red filter. Images were assessed subjectively using meiboscore by the two raters and drop-out percentages were assessed by ImageJ. RESULTS: There was no agreement in meiboscore and a minimal level of agreement in drop-out percentages between red filter meibography and infrared. Inter-rater reliability showed no agreement between two raters. Intra-rater reliability demonstrated weak agreement in rater 1 and no agreement in rater 2. CONCLUSION: Validity of the red filter meibography technique by smartphones is not yet satisfactory in evaluating drop-out. Further improvement on qualities of images must be done and research on subjective assessment was deemed necessary due to poor results of intrarater and inter-rater reliability.

Models for Meibomian gland dysfunction: In vivo and in vitro.

Meibomian gland dysfunction (MGD) is a chronic abnormality of the Meibomian glands (MGs) that is recognized as the leading cause of evaporative dry eye worldwide. Despite its prevalence, however, the pathophysiology of MGD remains elusive, and effective disease management continues to be a challenge. In the past 50 years, different models have been developed to illustrate the pathophysiological nature of MGD and the underlying disease mechanisms. An understanding of these models is crucial if researchers are to select an appropriate model to address specific questions related to MGD and to develop new treatments. Here, we summarize the various models of MGD, discuss their applications and limitations, and provide perspectives for future studies in the field.

Cellular senescence promotes meibomian gland dysfunction in a chronic graft-versus-host disease mouse model.

PURPOSE: Aging is a well-established risk factor for meibomian gland dysfunction (MGD). We previously reported an accelerated cellular senescence phenomenon in the lacrimal glands of a murine model of chronic graft-versus-host disease (cGVHD). Herein, we aimed to elucidate the relationship between cellular senescence and MGD in cGVHD mice, utilizing the senolytic agent ABT-263. METHODS: A cGVHD mouse model was established through allogeneic bone marrow transplantation (BMT) from B10.D2 to BALB/c mice. Subsequently, cGVHD mice were treated with either ABT-263 or vehicle. The eyelids of recipients were analyzed at 4-week intervals post-BMT in both groups. RESULTS: Meibomian gland (MG) area was significantly smaller in cGVHD mice than in syngeneic control mice. ABT-263-treated mice retained a significantly larger MG area than their vehicle-treated counterparts. Pathological and immunohistochemical examinations revealed significant reductions in eyelid tissue inflammation and pathological fibrosis in the ABT-263 group compared to that in the vehicle-treated group. Additionally, expression of DNA damage markers, senescent cell markers, and senescence-associated secretory phenotype (SASP) factors was elevated in the eyelids of cGVHD mice compared with that in syngeneic mice. The expression of these cellular senescence-associated molecules was considerably suppressed in ABT-263-treated eyelids compared to that in vehicle-treated ones. CONCLUSIONS: Cellular senescence, along with expression of SASP factors, exhibited increased activity in the eyelids, particularly in the MGs of cGVHD mice. ABT-263 mitigated the severity of MGD. These findings highlight the potential of targeting cellular senescence as an effective approach for MGD treatment in cGVHD.

Is there a relationship between the severity of disease in major depressive disorder patients and dry eye disease?

PURPOSE: To investigate dry eye disease (DED) in newly diagnosed patients with depressive disorder (MDD). METHOD: This observational study included 48 MDD patients in Group 1 and 20 healthy controls in Group 2. Psychiatric and ophthalmic examinations, Beck Depression Inventory (BDI), Ocular Surface Disease Index (OSDI), Schirmer's test, tear breakup time (TBUT), Meibomian gland dysfunction (MGD), and ocular staining were conducted. The results were statistically compared. RESULTS: The participants, comprising 32 men and 36 women, had a mean age of 31.08 ± 11.7 years (18-64 years). Group 1 had a mean BDI score of 30.87 ± 8.56, while Group 2 had a score of 1.3 ± 1.3 (p < 0.001). In Group 1, 28 patients were diagnosed with DED, whereas in Group 2, six subjects were diagnosed with DED. The mean Schirmer's results in Group 1 and Group 2 were (mm/5 min) 10.87 ± 2.44 and 12.70 ± 2.3, respectively, and were significantly lower in Group 1 (p < 0.001). The mean OSDI scores in Group 1 (34.95 ± 15.8) were significantly higher compared to Group 2 (3.2 ± 3.1) (p < 0.001). There was no significant difference in mean TBUT between Group 1 (9.41 ± 2.6 s) and Group 2 (9.8 ± 0.61 s) (p > 0.05). Significant correlations were found between BDI scores and Schirmer's results as well as OSDI scores (p < 0.05, p = 0.02, respectively). No statistically significant correlations were found between BDI scores and TBUT or MGD (p > 0.05). CONCLUSION: DED was found to be more prevalent in the MDD group. The severity of MDD and DED, as indicated by BDI, OSDI, and Schirmer's results, was found to be correlated. It was observed that patients with higher depression scores had more severe dry eye. As a result, we recommend performing ophthalmic examinations in newly diagnosed MDD patients.

Evaluation of Meibomian gland dysfunction using meibography in patients with xeroderma pigmentosum.

PURPOSE: To assess Meibomian gland dysfunction using meibography in patients with xeroderma pigmentosum and correlate with ocular surface changes. METHODS: This cross-sectional study evaluated patients with xeroderma pigmentosum. All patients underwent a comprehensive and standardized interview. The best-corrected visual acuity of each eye was determined. Detailed ophthalmic examination was conducted, including biomicroscopy examination of the ocular surface, Schirmer test type I, and meibography, and fundus examination was also performed when possible. Meibomian gland dysfunction was assessed by non-contact meibography using Oculus Keratograph® 5M (OCULUS Inc., Arlington, WA, USA). Saliva samples were collected using the Oragene DNA Self-collection kit (DNA Genotek Inc., Ottawa, Canada), and DNA was extracted as recommended by the manufacturer. Factors associated with abnormal meiboscores were assessed using generalized estimating equation models. RESULTS: A total of 42 participants were enrolled, and 27 patients underwent meibography. The meiboscore was abnormal in the upper eyelid in 8 (29.6%) patients and in the lower eyelid in 17 (62.9%). The likelihood of having abnormal meiboscores in the lower eyelid was 16.3 times greater than that in the upper eyelid. In the final multivariate model, age (p=0.001), mutation profile (p=0.006), and presence of ocular surface malignant tumor (OSMT) (p=0.014) remained significant for abnormal meiboscores. For a 1-year increase in age, the likelihood of abnormal meiboscores increased by 12%. Eyes with OSMT were 58.8 times more likely to have abnormal meiboscores than eyes without ocular surface malignant tumor. CONCLUSION: In the final model, age, xeroderma pigmentosum profile, previous cancer, and clinical alterations on the eyelid correlated with a meiboscore of ≥2. Meibomian gland dysfunction was common in patients with xeroderma pigmentosum, mainly in the lower eyelid. The severity of Meibomian gland dysfunction increases with age and is associated with severe eyelid changes.

First-in-human Clinical Trial of a Novel Eyelid warming Device in Meibomian Gland Dysfunction.

BACKGROUND: Meibomian gland dysfunction (MGD) causes significant patient morbidity as well as economic burden. OBJECTIVES: To evaluate a novel eyelid warming and a neuro-stimulating device that delivers heat via low-level infrared radiation to the eyelids of patients with MGD. METHODS: In this prospective interventional study, patients with MGD were recruited at a single medical center. The main outcome measures included changes in tear break-up time (TBUT), Schirmer's test, and Ocular Surface Disease Index (OSDI), overall satisfaction, and corneal signs of dry eye. Patients were instructed to use the device twice daily for 5 minutes on each eye for a total of 14 days. Follow-up assessments were performed after the 2-week treatment. RESULTS: A total of 10 patients were included; mean age was 67 ± 16 years; six males (60%). Changes in pre- vs. post-treatment TBUT (5.0-6.11), OSDI (28.1-23.9), and Schirmer score (8.67-7.11) were not statistically significant. Over a course of 243 treatments, 131 (54%) demonstrated improvement in symptoms, 40% found no change, and 6% experienced worsening of symptoms. General satisfaction was observed overall in 80% of the patients. No adverse events were observed. CONCLUSIONS: In this first study of a novel eyelid warming device, overall subjective satisfaction was reported in 80% of patients. Potential advantages of this user-friendly device include its ability to improve MGD and tear film stability, as well as symptomatic relief, while allowing the user to continue with normal daily functioning while undergoing treatment.

LipiFlow for the treatment of dry eye disease.

BACKGROUND: Meibomian gland dysfunction (MGD) is the most common underlying cause of dry eye disease (DED). MGD leads to pathological alteration of the composition or quantity of meibum, or both, which subsequently results in tear evaporation and the typical signs and symptoms associated with DED. The LipiFlow Thermal Pulsation System (LipiFlow) is a medical device used to treat MGD in office; however, it is unclear if LipiFlow can outperform other DED treatments. OBJECTIVES: To evaluate the effectiveness of LipiFlow for treating DED signs and symptoms and the safety of LipiFlow compared with sham or other available treatments for MGD in adults. SEARCH METHODS: The Cochrane Eyes and Vision Information Specialist searched the electronic databases for randomized controlled trials. There were no restrictions on language or date of publication. We searched the Cochrane Central Register of Controlled Trials (CENTRAL, including the Cochrane Eyes and Vision Trials Register; 2022, Issue 6), MEDLINE Ovid, Embase.com, PubMed, LILACS (Latin American and Caribbean Health Science Information database), ClinicalTrials.gov, and World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) electronic databases. We also examined the reference lists of identified trials, review articles, and guidelines for information about relevant trials that may not have been identified by our search strategy. We contacted investigators regarding ongoing trials. The last database search was performed on 24 October 2022. SELECTION CRITERIA: We included studies conducted in adults (over 18 years of age) with DED or MGD as defined by the primary trial investigators. We imposed no restrictions on race, ethnicity, or sex. We considered trials involving contact lens wearers if they were equally represented between groups. DATA COLLECTION AND ANALYSIS: We applied standard Cochrane methodology. MAIN RESULTS: We included 13 trials that randomized a total of 1155 participants (28 to 236 participants randomized per study). Six trials were conducted in the USA, three in China, two in Thailand, one in France, and one in Italy. Eight trials were of single-center design, while four trials were of multicenter design; one trial did not report the number of participating centers. Study characteristics The study population of the included trials was 66% female (range 48% to 80%), with an age range of 19 to 86 years. LipiFlow, used as a stand-alone intervention, was compared with basic warm compresses in five studies, thermostatic device in five studies, oral intervention in one trial, and topical dry eye medications in one trial. LipiFlow was also evaluated together with eyelid hygiene product versus eyelid hygiene products alone in one trial. Findings Five trials compared LipiFlow with a basic warm compress applied for varying durations and frequencies during the trial period; only one of these trials combined a warm compress with eyelid massage. Analyzing symptom scores by different questionnaires (Ocular Surface Disease Index [OSDI] and Standard Patient Evaluation of Eye Dryness [SPEED]) yielded conflicting evidence of a difference in symptoms between LipiFlow and basic warm compresses after four weeks. There was no evidence of a difference in meibomian gland expression, meibum quality, or tear breakup time when comparing LipiFlow with basic warm compresses. Another five trials compared LipiFlow with thermostatic devices. Analysis of symptom scores at four weeks showed that thermostatic devices had reduced OSDI scores by a mean difference (MD) of 4.59 (95% confidence interval [CI] 1.23 to 7.95; I2 = 0, P = 0.007; 553 participants; very low certainty evidence) as compared with LipiFlow. When we compared LipiFlow plus eyelid hygiene with eyelid hygiene alone, there was no evidence of difference in signs or symptoms at any time point evaluated. Only one trial compared LipiFlow with a topical DED medication (lifitegrast 5%). The single-trial estimate suggested that 5% lifitegrast may increase meibomian gland expression scores compared with LipiFlow at day 42 (MD -1.21, 95% CI -2.37 to -0.05; 50 participants; low certainty evidence) by using a meibomian gland expression scale of 0 to 8. One trial compared LipiFlow with an oral intervention (doxycycline), finding that LipiFlow may result in significantly better SPEED scores than doxycycline at three months (MD -4.00, 95% CI -7.33 to -0.67; 24 participants; very low certainty evidence). No other significant differences in signs or symptoms were found between LipiFlow and doxycycline at three months. We did not find any other statistically significant differences in symptoms or signs for any other analysis performed in this review at the one- to four-week time point. Adverse events No trial reported any intervention-related, vision-threatening adverse events. AUTHORS' CONCLUSIONS: LipiFlow performs similarly to other commonly used DED treatments with regard to DED signs and symptoms. The best available evidence was deemed to have a high level of bias, leading to low or very low certainty evidence. Additional research with adequate masking, a standardized testing methodology, and a sample representative of the MGD population is therefore needed before any firm conclusions can be drawn regarding comparative benefits and harms.

Higher incidence of meibomian gland dysfunction in postmenopausal women with primary acquired nasolacrimal duct obstruction.

PURPOSE: This study aimed to investigate the incidence of meibomian gland dysfunction (MGD) in postmenopausal women with primary acquired nasolacrimal duct obstruction (PANDO) and enables ophthalmologists to pay attention to ocular surface damage before surgery. METHODS: 165 postmenopausal women with PANDO and 115 postmenopausal women with a normal lacrimal drainage system were enrolled in this prospective study. Based on the results of lacrimal duct irrigation and age, the participants were further subdivided. The incidence of different severities of MGD in different groups was calculated and analyzed by the chi-squared test. RESULTS: The incidence of MGD in the PANDO group was 81.21%, and in the control group, it was 46.96%, which was significantly higher in the presence of PANDO (p < 0.001). The incidence of severe MGD in the complete and incomplete PANDO groups was higher than that in the control group (all p < 0.05), and no significant differences were observed between the complete and incomplete PANDO groups. The incidence of moderate MGD was significantly higher in the complete PANDO group than in the control group (p < 0.001). When age was considered an independent variable, the results revealed a significant value for patients aged < 70 years (p < 0.001). CONCLUSIONS: Our study revealed a prodominantly high incidence of MGD in postmenopausal women with PANDO, especially in a complete PANDO or aged < 70 years. Ophthalmologists need to pay close attention to MGD in postmenopausal women with PANDO.

Urban Particulate Matter Triggers Meibomian Gland Dysfunction.

Purpose: The meibomian gland (MG), as the largest modified sebaceous gland, is potentially damaged by urban particulate matter (UPM) based on epidemiological evidence, but the specific experimental mechanisms remain unknown. This study investigated the effects of UPM on MG dysfunction (MGD) in rodent models. Methods: Female C57BL/6J mice received eye drops containing UPM suspension or PBS for 14 days. The proliferative capacity and progenitor of MG were evaluated by immunofluorescence. Cell apoptosis was confirmed by TUNEL assay, along with the analysis of caspase family expression. Lipid accumulation was visualized by Oil Red O staining and LipidTox staining. Ductal hyperkeratinization, neutrophil infiltration, and pyroptosis activation were detected through immunostaining. The relative gene expression and signaling pathway activation were determined by Western blot analysis. Results: Administration of UPM caused MGD-like clinical signs, manifested as distinct corneal epithelial erosion, increased MG orifice occlusion, and glandular dropout. UPM exposure significantly induced progenitor loss, cellular apoptosis, and lipogenic disorder in MG, by reducing P63/Lrig1 expression and increasing cleaved caspase-8, -9, and -3 and meibum lipogenic protein (HMGCR/SREBP-1) expression. UPM-treated mice exhibited ductal hyperkeratinization and neutrophil recruitment. Simultaneously, pyroptosis was motivated, as indicated by the heightened expression of NLRP3 and the cleavage of caspase-1 and -4 and gasdermin D, as well as the increase in IL-1ß and IL-18 downstream. The underlying pathological mechanisms of UPM involve the phosphorylation of mitogen-activated protein kinase and nuclear factor-κB. Conclusions: These results provided direct evidence for the toxicity of UPM in MG. UPM-induced activation of pyroptosis and mitogen-activated protein kinase/nuclear factor-κB signaling pathway might account for the inflammatory MGD.

New advances in medical management of dry eye: optimizing treatment strategies for enhanced relief.

PURPOSE: Dry eye disease (DED) is a prevalent ocular surface disease that is conventionally characterized by tear film hyperosmolarity and instability. This review presents a summarized classification of DED, followed by a comprehensive discussion of the most recent topical and systemic medications and clinical recommendations for selecting the most appropriate option for each patient. METHODS: An extensive literature search was conducted on electronic databases, such as PubMed, Scopus, and Web of Science, using keywords including "dry eye syndrome," "ocular surface disease," "medical management," "artificial tears," "topical immunomodulators," and "meibomian gland dysfunction." RESULTS: The underlying reasons for DED can range from insufficient aqueous tear production to increased tear evaporation. Recent literature has provided a more in-depth understanding of the pathophysiology of DED by examining the tear film's lipid, aqueous, and mucin layers. However, despite these advancements, medical management of patients with symptomatic DED has not fully reflected this modernized knowledge of its pathophysiology. CONCLUSION: To develop a rationalized strategy for treating DED, it is crucial to have updated knowledge of therapeutic options, their mechanisms of actions, and indications based on the DED type and underlying causes.

Need to Increase the Number of Intense Pulsed Light (IPL) Treatment Sessions for Patients with Moderate to Severe Meibomian Gland Dysfunction (MGD) Patients.

PURPOSE: To evaluate whether patients with moderate-to-severe meibomian gland dysfunction (MGD) will benefit from increasing the number of intense pulsed light (IPL) treatment sessions. METHODS: Ninety Asian adult with MGD (stages 3-4) were enrolled in this retrospective study. In Group1, 30 patients completed the five-session IPL treatment, 63.33% of which also received meibomian gland expression (MGX). In Group 2, 60 patients received three-session IPL treatment, 60.0% of which also accepted MGX. Both intragroup and intergroup analyses were conducted. RESULTS: The population characteristics, clinical baseline characteristics and therapeutic regimen were comparable between Group1 and Group2. The symptoms and most clinical indices improved after IPL treatment finished in both two groups. No statistical difference was found in any improvement level of all symptomatic and physical indices, including the Ocular surface disease index, tear break-up time, Demodex, corneal staining, meibum quality, meibomian gland expressibility, and MGD stage (all p ≥ 0.05) between the two groups at any time, not only month by month, but also at the terminal visit. However, the response rate of Group1 after the five-session treatment (70.00%) was increased compared to that of Group2 after the three-session treatment (63.33%). CONCLUSIONS: Increasing the number of IPL sessions is beneficial for patients with moderate to severe MGD to increase the response rate of treatment, rather than the improvement level. However, there is no need for patients who respond well to a routine number of IPL treatments to undergo additional IPL sessions.

The Yin and Yang of non-immune and immune responses in meibomian gland dysfunction.

Meibomian gland dysfunction (MGD) is a leading cause of dry eye disease and one of the most common ophthalmic conditions encountered in eye clinics worldwide. These holocrine glands are situated in the eyelid, where they produce specialized lipids, or meibum, needed to lubricate the eye surface and slow tear film evaporation - functions which are critical to preserving high-resolution vision. MGD results in tear instability, rapid tear evaporation, changes in local microflora, and dry eye disease, amongst other pathological entities. While studies identifying the mechanisms of MGD have generally focused on gland obstruction, we now know that age is a major risk factor for MGD that is associated with abnormal cell differentiation and renewal. It is also now appreciated that immune-inflammatory disorders, such as certain autoimmune diseases and atopy, may trigger MGD, as demonstrated through a T cell-driven neutrophil response. Here, we independently discuss the underlying roles of gland and immune related factors in MGD, as well as the integration of these two distinct mechanisms into a unified perspective that may aid future studies. From this unique standpoint, we propose a revised model in which glandular dysfunction and immunopathogenic pathways are not primary versus secondary contributors in MGD, but are fluid, interactive, and dynamic, which we likened to the Yin and Yang of MGD.

Sex Differences in the Prevalence of Meibomian Gland Dysfunction: A Mini Review.

PURPOSE: In this review, we aimed to investigate the literature on sex-specific prevalence of meibomian gland dysfunction (MGD) and to determine whether women or men are more at risk for MGD. METHODS: A search was conducted on PubMed using the terms: (Sex OR Gender OR prevalence) AND (Meibomian gland). RESULTS: Twenty-four relevant studies on MGD prevalence were identified, including 10 population-based and 14 hospital-based studies. Among the population-based studies, five studies reported higher rates among men, three studies found no differences, and one study observed higher rates among women. In the hospital-based studies, 10 studies reported no difference, two found higher rates among men, and one found higher among women. In the reviewed literature, there was a considerable variation between studies in terms of quality, sample size, age ranges, diagnostic criteria. CONCLUSIONS: While most of the population-based studies suggest a higher prevalence among men, the majority of clinic-based studies show no significant difference. Further research with larger samples and standardized criteria is needed to determine whether men are indeed more susceptible to MGD.

How does ocular graft-versus-host disease fit under the dry eye umbrella? A review.

Graft-versus-host disease (GVHD) is a systemic disease that can affect multiple organs as a consequence of an allogeneic haematopoietic stem cell transplant. One organ system that is often affected in GVHD is the eyes. Ocular GVHD (oGVHD) may involve various structures within the eye including the lacrimal glands, eyelids, conjunctiva, cornea, and nasolacrimal ducts, and is a source of morbidity in patients with GVHD. Common presenting features of GVHD overlap with dry eye disease (DED), including decreased tear production, epithelial disruption, and Meibomian gland dysfunction (MGD). In this review, we aim to compare oGVHD and DED to better understand the similarities and differences between the conditions, with a focus on pathophysiology, risk factors, clinical features, and treatments.

Complement activation products in tears of dry eye and meibomian gland dysfunction.

Sixty-seven patients (38 woman; median age, 69 years) were enrolled to assess complement activation products (CAPs) in tear fluid with/without dry eye (DE) and with/without meibomian gland dysfunction (MGD). Patients were divided into four groups based on the presence/absence of DE and MGD: group DM had both DE and MGD, group DN had DE without MGD, group NM had MGD without DE, and group NN had neither DE nor MGD. The levels of C3a and C5a in the collected tears were analyzed using a cytometric bead array. The C3a concentrations in the DM, DN, NM, and NN groups were 2326 pg/ml, 1411 pg/ml, 1821 pg/ml, and 978 pg/ml, respectively. The C5a concentrations in the DM, DN, NM, and NN groups were 24.7 pg/ml, 15.3 pg/ml, 24.1 pg/ml, and 12.9 pg/ml, respectively. The concentrations of C3a and C5a in the DM and NM groups were significantly higher than in the NN group (P < 0.05 for both comparisons). The CAPs in the tear fluid in MGD and DE increased. Local dysregulation of the innate immune system can be associated with the development of MGD and DE in elderly patients.