Meibomian Gland Disease: The Role of Gland Dysfunction in Dry Eye Disease

Assessment of Tear Osmolarity in Smokers Using TearLab and I-Pen Systems

Purpose. Smoking has a negative effect on health and ocular tear film. The purpose of the current study is to investigate the correlation between the TearLab and I-Pen osmolarity scores in smokers and compare them with those of non-smoking healthy males. Methods. Thirty male smokers (25.3 ± 2.2 years) participated in the study. An age-matched (22.9 ± 2.0 years) control group of non-smoking healthy males (N = 30) was also recruited for comparison purposes. The ocular surface disease index (OSDI) was completed first, followed by the TearLab and I-Pen osmolarity measurements. Results. The median TearLab osmolarity score was lower (P < 0.001) than that obtained using the I-Pen in both the study and the control groups. The OSDI scores and osmolality measurements were higher (P < 0.001) in smokers than in the control subjects. In the smoker group, there were moderate correlations between the OSDI scores and the measurements obtained using the TearLab (Spearman’s correlation coefficient, r = 0.463; P = 0.010) and I-Pen (r = 0.449; P = 0.013) systems. In addition, there was a strong correlation between the osmolarity scores obtained from the TearLab and I-Pen systems in smokers (r = 0.911; P < 0.001). Conclusion. The I-Pen scores in smokers were significantly higher than those obtained using TearLab. The TearLab scores showed small variations compared with those obtained using I-Pen. A strong correlation was found between the TearLab and I-Pen scores in smokers. The osmolarity TearLab and I-Pen scores were significantly higher in smokers compared with normal eye subjects.

Case report: Immune-mediated meibomian gland dysfunction following pembrolizumab therapy for advanced urothelial carcinoma

Ocular immune-related adverse events are a relatively rare complication of immune checkpoint inhibitors. Common ocular toxicities range from dry eyes to inflammatory uveitis and ocular myasthenia gravis. Here, we present the case of a 55-year-old woman with recurrent urothelial carcinoma of the ureter after initially being managed with neoadjuvant cisplatin-based chemotherapy and surgical resection. She was treated with pembrolizumab which was complicated by immune-mediated pneumonitis after the eighth cycle, which was managed with a prolonged steroid course. The patient also developed red eyes along with recurrent styes. Eye examination revealed decreased tear breakup time, expression of thick and turbid meibum, and meibomian gland atrophy on infrared meibography. The patient was diagnosed with suspected immune-mediated meibomian gland dysfunction (MGD) as a result of pembrolizumab, a previously unreported complication of immunotherapy. The goal of MGD therapy is to stabilize the tear film and minimize evaporation with lipid-based lubricants and other conservative treatments.

The role of sphingolipids in meibomian gland dysfunction and ocular surface inflammation

Inflammation occurs in response to tissue injury and invasion of microorganisms and is carried out by the innate and adaptive immune systems, which are regulated by numerous chemokines, cytokines, and lipid mediators. There are four major families of bioactive lipid mediators that play an integral role in inflammation - eicosanoids, sphingolipids (SPL), specialized pro-resolving mediators (SPM), and endocannabinoids. SPL have been historically recognized as important structural components of cellular membranes; their roles as bioactive lipids and inflammatory mediators are recent additions. Major SPL metabolites, including sphingomyelin, ceramide, ceramide 1-phosphate (C1P), sphingosine, sphingosine 1-phosphate (S1P), and their respective enzymes have been studied extensively, primarily in cell-culture and animal models, for their roles in cellular signaling and regulating inflammation and apoptosis. Less focus has been given to the involvement of SPL in eye diseases. As such, the aim of this review was to examine relationships between the SPL family and ocular surface diseases, focusing on their role in disease pathophysiology and discussing the potential of therapeutics that disrupt SPL pathways.

Induction of meibocyte differentiation by three-dimensional, matrigel culture of immortalized human meibomian gland epithelial cells to form acinar organoids

PURPOSE

Recent studies have shown that two-dimensional (2D) culture of primary rabbit and immortalized human meibomian gland epithelial cells (iHMGEC) do not recapitulate normal meibocyte differentiation and fail to express critical enzymes necessary for synthesis of meibum lipids. The purpose of this study was to test the hypothesis that 3D-spheroid culture of iHMGEC can facilitate meibocyte differentiation and induce the expression of acyl-CoA wax-alcohol acyltransferase 2 (AWAT2), shown to be required for synthesis of meibum wax esters.

METHODS

iHMGEC were suspended in matrigel/basement membrane matrix and grown in proliferation media to form distinct cell clusters or spheroids. Cells were then treated with serum-free, differentiation media (advanced DMEM/F12) with and without FGF10 and synthetic agonists for the nuclear lipid receptor, peroxisome proliferator activator receptor gamma (PPARγ). Cells were then evaluated for differentiation markers using western blotting, immunocytochemistry (ICC) and real-time PCR. Control cells were grown in standard 2D culture systems.

RESULTS

Under proliferative conditions, 3D culture induced the formation of KRT5+ spheroids that contained a Ki67+/P63+ undifferentiated, basal cell population. When spheroids were switched to differentiation media containing PPARγ agonists, two different organoid populations were detected, a KRT6low population that was AWAT2+/PPARγ+ and a KRT6high population that was AWAT2-/PPARγ-, suggesting that iHMGEC exhibit a dual differentiation potential toward either a ductal or meibocyte organoid phenotype.

CONCLUSION

The 3D culturing of iHMGEC can induce the formation of both meibocyte and ductal organoids and may thus serve as a better in vitro model system for studying the regulatory mechanisms controlling meibomian gland function.

Automatic identification of meibomian gland dysfunction with meibography images using deep learning

BACKGROUND

Artificial intelligence is developing rapidly, bringing increasing numbers of intelligent products into daily life. However, it has little progress in dry eye, which is a common disease and associated with meibomian gland dysfunction (MGD). Noninvasive infrared meibography, known as an effective diagnostic tool of MGD, allows for objective observation of meibomian glands. Thus, we discuss a deep learning method to measure and assess meibomian glands of meibography.

METHODS

We used Mask R-CNN deep learning (DL) framework. A total of 1878 meibography images were collected and manually annotated by two licensed eyelid specialists with two classes: conjunctiva and meibomian glands. The annotated pictures were used to establish a DL model. An independent test dataset that contained 58 images was used to compare the accuracy and efficiency of the deep learning model with specialists.

RESULTS

The DL model calculated the ratio of meibomian gland loss with precise values by achieving high accuracy in the identification of conjunctiva (validation loss < 0.35, mAP > 0.976) and meibomian glands (validation loss < 1.0, mAP > 0.92). The comparison between specialists' annotation and the DL model evaluation showed that there is little difference between the gold standard and the model. Each image takes 480 ms for the model to evaluate, almost 21 times faster than specialists.

CONCLUSIONS

The DL model can improve the accuracy of meibography image evaluation, help specialists to grade the meibomian glands and save their time to some extent.

Observation of Conjunctiva-Associated Lymphoid Tissue With In Vivo Confocal Microscopy in Healthy Patients and Patients With Meibomian Gland Dysfunction

PURPOSE

The purpose of this study was to assess the distribution and morphological variation of conjunctiva-associated lymphoid tissue (CALT) in healthy human subjects and patients with meibomian gland dysfunction (MGD) using laserscanningin vivo confocal microscopy.

METHODS

A total of 34 healthy subjects and 32 patients with MGD were enrolled. All subjects underwent a conventional examination consisting of slitlamp biomicroscopy, tear film break-up time, and the Schirmer test. In vivo microscopy was applied to analyze the morphological changes in the diffuse lymphoid layer and lymphoid follicles in CALT. Conjunctival impression cytology (CIC) of samples of patients' palpebral conjunctiva and immunofluorescence staining of CD4 and CD8 antibodies were also performed to indicate the immune response status of CALT.

RESULTS

In the MGD group, the density of diffuse lymphocytes ( P < 0.001), follicles ( P < 0.001), and perifollicular lymphocytes was higher ( P < 0.001) and the central reflection of the follicles was stronger ( P < 0.001) than in the control group, while there was no difference in the follicle area ( P = 0.758). Besides, diffuse lymphocyte density was correlated with telangiectasia, and follicular center reflection intensity was correlated with plugging. CIC immunofluorescence staining showed a higher percentage of CD4 + ( P < 0.001) and CD8 + ( P < 0.001) cells in the MGD group than in the control group.

CONCLUSIONS

Using laser scanning in vivo confocal microscopy and CIC immunofluorescence staining, we observed the activation of CALT in patients with MGD, and some CALT-related parameters correlated with the lid margin findings of patients with MGD.

Protein and polypeptide mediated delivery to the eye

Hybrid or recombinant protein-polymers, peptide-based biomaterials, and antibody-targeted therapeutics are widely explored for various ocular conditions and vision correction. They have been noted for their potential biocompatibility, potency, adaptability, and opportunities for sustained drug delivery. Unique to peptide and protein therapeutics, their production by cellular translation allows their precise modification through genetic engineering. To a greater extent than drug delivery to other systems, delivery to the eye can benefit from the combination of locally-targeted administration and protein-based specificity. Consequently, a range of delivery platforms and administration methods have been exploited to address the ocular delivery of peptide and protein biomaterials. This review discusses a sample of preclinical and clinical opportunities for peptide-based drug delivery to the eye.

The lack of correlation between symptoms and signs in patients with meibomian gland dysfunction: a secondary analysis of the multicenter, randomized controlled trial

Background

This study was performed to investigate the association between symptoms and signs in patients with meibomian gland dysfunction (MGD).

Methods

Data were obtained from 122 MGD patients who were recruited for intense pulsed light therapy from November 2017 to April 2018 and the severity of their symptoms and signs at baseline were observed and recorded. Spearman correlation analyses were performed to analyze the relationships between SPEED score and signs. Subjects were divided into different subgroups based on possible influencing factors, and the differences in symptoms and signs were compared between different subgroups. Then influencing factors were controlled by regression analysis to explore the relationship between symptoms and signs and the strong factors affecting symptoms and signs.

Results

Analysis of baseline data showed that SPEED scores were not correlated with TBUT, CFSS, MGYSS or any index of eyelid margin abnormality (p > 0.05). In addition, abnormalities of lid margins, including hyperemia, thickening, rounding, hyperkeratinization, and telangiectasia around orifices, were more likely to occur in older patients, menopausal patients, and patients living in northern China. Multiple linear regression analysis indicated that there was still no correlation between symptoms and signs (p > 0.05) after adjusting for influencing factors. Further analysis suggested that each influencing factor has different effects on symptoms and signs, among which menopause affects the SPEED score (R = -4.112, p = 0.025), and age and region have significant effects on eyelid margin abnormalities.

Conclusions

In conclusion, the results demonstrated a poor correlation between symptoms and signs in MGD patients. Age, hormone, and a dry environment may influence the disease, which suggests that the severity of the disease needs to be comprehensively assessed.

Differentiating primary dry eye disease from ocular neuropathic pain: implications for symptom management

CLINICAL RELEVANCE

Eyecare practitioners' management of ocular surface disease is essential in managing increasing dry eye disease (DED) presentations including ocular neuropathic pain (ONP). Topical Proxymetacaine offers a simple, readily available and practical method of detecting ONP in practice and can be used to differentiate ONP from DED by eyecare practitioners, when accompanied with an anterior segment examination.

BACKGROUND

Differentiating DED from ONP presents a significant opportunity to eyecare providers, allowing appropriate treatment choices for more adequate symptom control, greater patient satisfaction, and reduced emergent re-presentations. This study aims to differentiate patients presenting with DED symptoms into DED or ONP using a simple diagnostic tool, which can be used in practice to allocate appropriate treatment options for the patient's respective condition. A comparison of the prevalence of presentations of ONP presenting with DED symptoms in hospital ophthalmology settings and in optometric primary care settings will also be made.

METHODS

Patients with symptoms of DED were opportunistically recruited as they presented to ophthalmology outpatient clinics and primary care optometric services. Patients were then categorised as DED, ONP, or mixed DED/ONP based on their subjective response 30 seconds post-Proxymetacaine Hydrochloride 2% instillation.

RESULTS

Twenty-one patients were recruited, including 12 patients from ophthalmologic outpatient clinics and nine patients from primary care optometric services. Twelve patients were identified to have primary DED, while nine patients were identified to have ONP. 43% of patients presenting with DED symptoms had features of neuropathic pain in ophthalmologic outpatient presentations compared to 44% of patients in primary care optometric services.

CONCLUSION

Categorising DED and ONP patients by their response to Proxymetacaine can be used as a simple diagnostic tool in guiding future patient management and can be indicative of their potential response to topical therapies. The use of topical Proxymetacaine and the resultant change in ocular pain score can facilitate selection of patients who may benefit from centrally acting neuropathic pain agents over topical ocular therapy.

Activation of ADRB2/PKA Signaling Pathway Facilitates Lipid Synthesis in Meibocytes, and Beta-Blocker Glaucoma Drug Impedes PKA-Induced Lipid Synthesis by Inhibiting ADRB2

Meibomian gland dysfunction is one of the main causes of dry eye disease and has limited therapeutic options. In this study, we investigated the biological function of the beta 2-adrenergic receptor (ADRB2)/protein kinase A (PKA) pathway in lipid synthesis and its underlying mechanisms in human meibomian gland epithelial cells (HMGECs). HMGECs were cultured in differentiation media with or without forskolin (an activator of adenylate cyclase), salbutamol (an ADRB2 agonist), or timolol (an ADRB2 antagonist) for up to 4 days. The phosphorylation of the cAMP-response element-binding protein (CREB) and the expression of peroxisome proliferator activator receptor (PPAR)γ and sterol regulatory element-binding protein (SREBP)-1 were measured by immunoblotting and quantitative PCR. Lipid synthesis was examined by LipidTOX immunostaining, AdipoRed assay, and Oil Red O staining. PKA pathway activation enhanced PPARγ expression and lipid synthesis in differentiated HMGECs. When treated with agonists of ADBR2 (upstream of the PKA signaling system), PPARγ expression and lipid synthesis were enhanced in HMGECs. The ADRB2 antagonist timolol showed the opposite effect. The activation of the ADRB2/PKA signaling pathway enhances lipid synthesis in HMGECs. These results provide a potential mechanism and therapeutic target for meibomian gland dysfunction, particularly in cases induced by beta-blocker glaucoma drugs.

Voxel-Mirrored Homotopic Connectivity Is Altered in Meibomian Gland Dysfunction Patients That Are Morbidly Obese

Purpose: To investigate the altered functional connectivity (FC) of the cerebral hemispheres in patients with morbid obesity (MO) with meibomian gland dysfunction (MGD) by voxel-mirrored homotopic connectivity (VMHC). Methods: Patients and matched healthy controls (HCs) were recruited, and all subjects underwent functional resonance magnetic imaging (fMRI), and VMHC results were processed statistically to assess the differences in FC in different brain regions between the two groups. We further used ROC curves to evaluate the diagnostic value of these differences. We also used Pearson’s correlation analysis to explore the relationship between changes in VMHC values in specific brain regions, visual acuity, and Mini-Mental State Examination (MMSE) score. Conclusions: Patients with morbid obesity and MGD had abnormal FC in the cerebral hemispheres in several specific brain areas, which were mainly concentrated in pathways related to vision and perception and may correlate to some extent with the clinical presentations of the patients.

The effect of thermo-mechanical device (Tixel) treatment on evaporative dry eye disease - A pilot prospective clinical trial

PURPOSE

To examine the effects of treatment with a thermomechanical skin device to the eyelid area on the clinical signs and symptoms of patients who suffer from dry eye disease (DED) secondary to meibomian gland dysfunction (MGD).

METHODS

Forty patients aged 45 years or older with DED due to MGD were recruited. Both eyes (n = 80) of each patient received three treatments with the Tixel device (Novoxel®, Israel), with each treatment separated by a 2-week period. Treatment was applied across the upper and lower eyelids, with the same intensity, tip protrusion distance, and contact duration. Two additional follow-up visits were performed at 2-week intervals after treatment cessation. DED status was evaluated during each visit via SPEED II questionnaire, tear break-up time (TBUT), corneal staining score (CSS), MGD score, and frequency of lubricant use. Visual acuity (VA) was recorded during first and last visits.

RESULTS

Mean age was 64.3 ± 12.4 years and 72.5 % (n = 29) were female. 45 % (n = 18) had a history of blepharitis, 12.5 % (n = 5) had chalazia, and 17.5 % (n = 7) suffered from allergic conjunctivitis. Mean follow-up time was 2.1 ± 0.6 months. Comparing the first and last visits, all parameters showed significant improvement after Tixel treatment: mean SPEED II scores (16.5 ± 5.9 to 11.8 ± 6.7, p < 0.001), CSS (2.0 ± 1.3 to 0.5 ± 0.9, p < 0.001), TBUT (2.7 ± 0.8 s to 6.5 ± 2.2 s, p < 0.001), MGD score (2.7 ± 0.5 to 1.2 ± 0.4, p < 0.001), and rate of lubricant use (3.4 ± 2.4 per day to 1.9 ± 2.0, p < 0.001). VA also improved (0.10 ± 0.11 logMAR to 0.08 ± 0.10 logMAR, p < 0.05). No major side effects were observed.

CONCLUSIONS

In this pilot study Tixel treatment induced significant improvement of signs and symptoms among patients with DED due to MGD. Benefits persisted for at least one month. Further randomized controlled double-blinded studies are needed.

Effect of eyeliner and mascara use on tear film and meibomian glands

PURPOSE

This study was conducted to see whether eyeliner, mascara, or combined eyeliner and mascara (EM) use affects tear production, tear film stability, and meibomian gland (MG) loss.

METHODS

Two hundred and twenty healthy women underwent noninvasive tear break-up time (NTBUT) measurement, meibography, and Schirmer testing. Study groups were no makeup (NM) group, eyeliner-only group, mascara-only group, and those who used both EM. The one-way analysis of variance test was used for group comparisons. Chi-square test was used for meiboscale comparison.

RESULTS

NTBUT (seconds) results were 11.5 ± 4.8 (no makeup), 21.3 ± 69 (eyeliner only), 21.8 ± 6.5 (mascara only), and 22.5 ± 7.0 (eyeliner-mascara). The differences between groups were significant (P < 0.0001). All makeup groups (eyeliner only, mascara only, eyeliner-mascara) had significantly diminished values compared with NM group (P < 0.001, P < 0.001 and P = 0.003, respectively). Schirmer test (millimeters) results were 22.7 ± 6.4 (NM group), 21.3 ± 6.9 (eyeliner only), 21.8 ± 6.5 (mascara only), and 22.5 ± 7.0 (eyeliner-mascara) with no significant differences between groups (P = 0.66). Meiboscale grading revealed that NM group had significantly lower values of MG loss compared with eyeliner-only (EO) (P = 0.01), mascara-only (MO) (P = 0.002), and eyeliner-mascara groups (P = 0.007). There were no significant differences between EO and MO (P = 0.31), EO and eyeliner-mascara (P = 0.39), or MO and eyeliner-mascara groups (P = 0.91).

CONCLUSION

None of the makeup groups had changes in Schirmer wetting. All eye cosmetic groups have significant changes of NTBUT and meibography compared with NM subjects, and yet combined use of EM does not affect ocular surface more adversely than their separate use.

The Predictive Potential of Altered Voxel-Based Morphometry in Severely Obese Patients With Meibomian Gland Dysfunction

Objective

To investigate voxel-based morphometry (VBM) by using magnetic resonance imaging (MRI) in meibomian gland dysfunction patients with severe obesity (PATs) and to explore the application of VBM in the early diagnosis, prevention of cognitive impairment and targeted treatment of this disease.

Methods

Sixteen PATs and 12 healthy controls (HCs) were enrolled and underwent MRI. Whole-head images were analyzed using VBM and data were compared between groups using an independent samples t-test. Receiver operating characteristic (ROC) curves were utilized to assess the diagnostic value of this approach. Mini-mental state examination (MMSE) scores were used to assess cognitive impairment and were analyzed using an independent samples t-test.

Results

Compared with HCs, the VBM values in PATs were reduced in the left cerebellum and right thalamus but increased in the right brainstem, right precuneus and right paracentral lobule. The results of ROC curve analysis indicated that VBM may be useful in meibomian gland disease diagnosis. Comparison of MMSE scores between groups showed mild cognitive impairment in PATs.

Conclusion

PATs showed altered VBM values in some brain areas. These findings may provide information about the pathophysiology of meibomian gland dysfunction and may help to explain the underlying mechanisms of clinical manifestations in PATs, such as cognitive impairment. Abnormal VBM values in these brain areas may serve as predictive factors for development of meibomian gland disease in severely obese people and as indicators for individualized treatment.

Relationships between ocular surface sphingomyelinases, Meibum and Tear Sphingolipids, and clinical parameters of meibomian gland dysfunction

PURPOSE

Sphingolipids (SPL) are a class of lipid molecules that play important functional and structural roles in our body and are a component of meibum. Sphingomyelinases (SMases) are key enzymes in sphingolipid metabolism that hydrolyze sphingomyelin (SM) and generate ceramide (Cer). The purpose of this study was to examine relationships between ocular surface SMases, SPL composition, and parameters of Meibomian gland dysfunction (MGD).

METHODS

Individuals were grouped by meibum quality (n = 25 with poor-quality, MGD, and n = 25 with good-quality, control). Meibum and tears were analyzed with LC-MS to quantify SPL classes: Cer, Hexosyl-Ceramide (Hex-Cer), SM, Sphingosine (Sph), and sphingosine 1-phosphate (S1P). SMase activity in tears were quantified using a commercially available 'SMase assay'. Statistical analysis included multiple linear regression analyses to assess the impact of SMase activity on lipid composition, as well as ocular surface symptoms and signs of MGD.

RESULTS

Demographic characteristics were similar between the two groups. nSMase and aSMase levels were lower in the poor vs good quality group. aSMase activity in tears negatively correlated with SM in meibum and tears and positively with Sph in meibum and S1P in tears. Lower SMase activity were associated with signs of MGD, most notably Meibomian gland dropout.

CONCLUSION

This study suggests that individuals with MGD have reduced enzymatic activity of SMases in tears. Specifically, individuals with poor vs good meibum quality were noted to have alterations in SMase activity and SPL composition of meibum and tears which may reflect deviations from normal lipid metabolism in individuals with MGD.

The preoperative management of meibomian gland dysfunction prior to corneal refractive surgery

PURPOSE OF REVIEW

To describe the significance of meibomian gland dysfunction (MGD) in corneal refractive surgery and to describe available approaches to preoperative evaluation and treatment based on current research.

RECENT FINDINGS

There are several methods available for the evaluation and treatment of MGD. These are relevant for refractive surgeons to understand, as the presence of MGD preoperatively plays a role in the severity of MGD after corneal refractive surgery. Refractive surgery itself can exacerbate MGD. Treatment of MGD prior to surgery may have a meaningful impact on postoperative MGD.

SUMMARY

Surgeons should include meibomian gland assessment in the preoperative refractive evaluation and should treat MGD proactively prior to performing refractive surgery. Relevant information in this field is growing; additional prospectively designed studies are needed to further enhance our understanding.

Correlation of meiboscale symptom score and sign score for primary meibomian gland dysfunction in Indian eyes - A cross-sectional study

Purpose:

To evaluate the correlation of Meiboscale with symptom score (Ocular Surface Disease Index [OSDI]) and meibomian gland dysfunction (MGD) sign score.

Methods:

We performed a cross-sectional hospital-based study of 53 patients of primary MGD who filled the OSDI questionnaire form and underwent complete ocular examination. The MGD sign score was calculated in both eyes using the sum of six grading systems proposed by Arita et al. in 2016. The participants underwent imaging of the upper and lower eyelids of both eyes (212 eyelids) by specular microscope. The area of meibomian gland loss (MGL) was visually assessed and scored using the Meiboscale photographic card. Correlation between these three values – OSDI score, sign score, and MGL score based on Meiboscale - was calculated using Spearman’s correlation analysis and Jonckheere–Terpstra (J–T) test. Correlation coefficient r_s > 0.5 was considered clinically significant.

Results:

Associations between MGL score and OSDI score, as well as between OSDI and sign score were statistically significant, but not clinically significant (r_s = 0.3684, P < 0.001 and r_s = 0.41179, P < 0.001, respectively). The association between MGL score and MGD sign score was statistically as well as clinically significant (r_s = 0.8392, P < 0.001). J–T test revealed large effect size (P < 0.001, r-effect = 0.93).

Conclusion:

The Meiboscale card had not been tested for utility in the Indian outpatient setting yet. Meiboscale can be used for reliable assessment and grading of MGD, and has clinical utility similar to the sum of six MGD sign scores. Additionally, assessment of symptoms using OSDI or a similar questionnaire is also recommended.

Latest developments on meibomian gland dysfunction: Diagnosis, treatment and management

Background: Meibomian gland dysfunction (MGD) is one of the leading causes of evaporative dry eye disease and one of the most common ophthalmic conditions found in clinical practice. Meibomian gland dysfunction tends to be overlooked because its signs and symptoms do not cause blindness. Meibomian gland dysfunction is characterised by the obstruction of the meibomian gland terminal ducts resulting in tear film instability.Aim: The purpose of this article was to provide an update on MGD’s diagnosis and treatment.Method: A literature review was conducted using search engines such as Google Scholar, Medline and ScienceDirect databases. Keywords such as MGD diagnosis and management and treatment of MGD were used to search the databases.Results: A total of 44 relevant papers were reviewed. These papers were then curated to include only those concerning diagnosis of meibomian gland dysfunction, treatment of meibomian gland dysfunction and management options of meibomian gland dysfunction. The references of individual papers from the curated results were checked to yield a further 13 papers.Conclusion: Meibomian gland dysfunction is not a single entity but is multifactorial in origin; however, our understanding of the condition is evolving rapidly because of newer imaging technology. There is no gold standard treatment option for MGD, but many options are available that include medications and other procedures. 

Prevalence and Characteristics of Dry Eye Disease After Cataract Surgery: A Systematic Review and Meta-Analysis

Dry eye disease (DED) after cataract surgery is associated with various risk factors, while causing a wide range of heterogeneous symptoms including decreased quality of vision. This systematic review and meta-analysis aimed to determine the prevalence and characteristics of DED after cataract surgery. We searched PubMed and EMBASE and included studies on patients with DED after cataract surgery, between January 2011 and June 2020. Study-specific estimates (DED prevalence rates after cataract surgery in patients without preexisting DED) were combined using one-group meta-analysis in a random-effects model. We included 36 studies published between 2013 and 2020. We included nine of these in the meta-analysis of DED prevalence after cataract surgery. Overall 37.4% (95% CI 22.6-52.3; 206/775) of patients without preexisting DED developed DED after cataract surgery. The risk factors for DED after cataract surgery included age, female sex, systemic diseases, systemic medications, psychiatric conditions, preexisting DED, meibomian gland dysfunction, preservatives in eye drops, surgery techniques, and lifestyle. DED severity peak occurred 1 day postoperatively and persisted for at least 1-12 months following cataract surgery; therefore, consistent follow-up for DED is warranted for at least 1 month after cataract surgery. Topical administration of preservative-free diquafosol tetrasodium solution and preoperative meibomian gland treatment were effective in preventing and treating DED following cataract surgery. As more than one-third of patients develop DED after cataract surgery, careful DED management and treatment is needed after cataract surgery to improve satisfaction and vision quality.

Melatonin Attenuates LPS-Induced Proinflammatory Cytokine Response and Lipogenesis in Human Meibomian Gland Epithelial Cells via MAPK/NF-κB Pathway

Purpose

Inflammation contributes to the development of meibomian gland dysfunction (MGD) under specific disease conditions, but the underlying mechanisms remain elusive. We examined whether lipopolysaccharide (LPS) induced a proinflammatory cytokine response and lipogenesis in human meibomian gland epithelial cells (HMGECs) and whether melatonin (MLT), a powerful anti-inflammatory regent in the eyes, could protect against LPS-induced disorders.

Methods

Human meibomian gland (MG) tissues and immortalized HMGECs were stained to identify Toll-like receptor (TLR) 4 and MLT receptors (MT₁ and MT₂). HMGECs were pretreated with or without MLT and then stimulated with LPS. Then, TLR4 activation, cytokine levels, lipid synthesis, apoptosis, autophagy, and MAPK/NF-κB factor phosphorylation in HMGECs were analyzed.

Results

TLR4, MT₁, and MT₂ were expressed in human MG acini and HMGECs. Pretreatment with MLT inhibited the TLR4/MyD88 signaling and attenuated proinflammatory cytokine response and lipogenesis in LPS-stimulated HMGECs, which manifested as decreased production of cytokines (IL-1β, IL-6, IL-8, and TNF-α), reduced lipid droplet formation, and downregulated expression of meibum lipogenic proteins (ADFP, ELOVL4, and SREBP-1). Phospho-histone H2A.X foci, lysosome accumulation, and cytoplasmic cleaved caspase 3/LC3B-II staining were increased in LPS-stimulated HMGECs, indicating enhanced cell death mediated by apoptosis and autophagy during LPS-induced lipogenesis. MLT downregulated cleaved caspase 3 levels and the Bax/Bcl-2 ratio to alleviate apoptosis and ameliorated the expression of Beclin 1 and LC3B-II to inhibit autophagy. The protective mechanisms of MLT include the inhibition of MAPK and NF-κB phosphorylation.

Conclusions

MLT attenuated lipogenesis, apoptosis, and autophagy in HMGECs induced by proinflammatory stimuli, indicating the protective potential of MLT in MGD.

Evaluation of ocular surface parameters in dogs with and without meibomian gland dysfunction

BACKGROUND

Interest in meibomian gland dysfunction (MGD) is growing in veterinary medicine. However, research on MGD in dogs is lacking. The aims of this study were to compare the interferometry grades, tear meniscus height (TMH) and non-invasive tear break-up time (NIBUT) grades between dogs with and without MGD.

METHODS

Routine ophthalmic examination, interferometry, NIBUT assessment, TMH measurement and meibography were performed. Age and Schirmer tear test-1 (STT-1) results were compared between the control and MGD groups using Student's t-test. Interferometry grades, NIBUT grades and TMH were compared between the two groups using Mann-Whitney U-test.

RESULTS

There was no significant difference in age between the two groups (p = 0.279). STT-1 (p = 0.024), interferometry (p = 0.004) and NIBUT grades (p = 0.012) were significantly lower in the MGD group than in the control group. No significant difference in TMH values (p = 0.587) was observed between the two groups. While the control group included 18 and seven eyes in meiboscore 0 and 1, in MGD group, 12, eight, five and three eyes were included in meiboscore 0, 1, 2 and 3, respectively.

CONCLUSIONS

Low interferometry and NIBUT grades were associated with MGD, suggesting decreased meibum and disrupted tear film quality. TMH did not differ between the two groups. Meibography could aid in the diagnosis of MGD in severe cases, although it could not detect early MGD in the dogs in this study.

Meibomian Glands and Tear Film Findings in Type 2 Diabetic Patients: A Cross-Sectional Study

Background

The characteristics of the meibomian gland and tear film in patients with type 2 diabetes (T2D) with different glycemic control levels and diabetic durations remain largely unexplored. This study aimed to identify the association of dry eye and meibomian gland dysfunction (MGD) in T2D.

Materials and Methods

Ninety-nine patients with type 2 diabetes mellitus (DM group), 33 dry eye patients without diabetes mellitus (DE group), and 40 normal subjects (NC group) were recruited for this study. Participants were evaluated with an Ocular Surface Disease Index (OSDI) questionnaire, tear film breakup time (BUT), the Schirmer I test (SIT), corneal fluorescein staining (FL), lipid layer thickness (LLT), and MGD parameters. Glycosylated hemoglobin (HbA_1c) and duration of diabetes were recorded.

Results

The SIT value in the DM group was higher than that of the DE group (p < 0.05). The BUT and LLT were lower, and MGD parameters were higher in the DM group than those of the DE and NC groups (p < 0.05). In the DM group, 47 patients were diagnosed with dry eye (DM + DE group), whereas 40 patients without dry eye were categorized as the DM − DE group. The SIT, BUT, and LLT values in the DM − DE group were higher (p < 0.01), and MGD parameters were lower (p < 0.01) in the DM − DE group than those of the DM + DE group. The MGD parameters were higher in the DM − DE group than those in the NC group (p < 0.05). The HbA_1c levels were correlated with OSDI, BUT, LLT, FL, and MGD parameters (p < 0.001) in the DM group. However, in patients with low HbA_1c, normal SIT value, and low OSDI, the MGD parameters were higher than those in the NC group (p < 0.05). The duration of diabetes positively correlated with MGD parameters (p < 0.001).

Conclusion

Asymptomatic MGD may be an early sign of dry eye and ocular discomfort in T2D. The MGD parameters were associated with the HbA_1c level and diabetic duration.

A Practical Approach to Severity Classification and Treatment of Dry Eye Disease: A Proposal from the Mexican Dry Eye Disease Expert Panel

Dry eye disease (DED) has a higher prevalence than many important systemic disorders like cardiovascular disease and diabetes mellitus, representing a significant quality of life burden for the affected patients. It is a common reason for consultation in general eye clinics worldwide. Nowadays, the diagnostic and therapeutic approach at the high corneal and ocular surface specialty level should be reserved for cases of severe and chronic dry eye disease associated with systemic autoimmune diseases or complicated corneal and ocular surface pathologies. In such cases, the diagnostic and therapeutic approach is often complex, elaborate, time-consuming, and costly due to the use of extensive dry eye questionnaires, noninvasive electronic diagnostic equipment, and clinical laboratory and ancillary tests. However, other eye care specialists attend a fair amount of DED cases; therefore, its diagnosis, classification, and management should be simple, practical, achievable, and effective. Considering that many patients attending non-specialized dry eye clinics would benefit from better ophthalmological attention, we decided to elaborate a practical DED classification system based on disease severity to help clinicians discriminate cases needing referral to subspecialty clinics from those they could attend. Additionally, we propose a systematic management approach and general management considerations to improve patients' therapeutic outcomes according to disease severity.

In Vivo Confocal Microscopy in Different Types of Dry Eye and Meibomian Gland Dysfunction

In vivo confocal microscopy (IVCM) imaging is increasingly popular in ocular surface disease diagnosis and management. We conducted a systematic review to update the use of IVCM in the diagnosis and treatment of dry eye and meibomian gland dysfunction (MGD). A literature review was conducted on IVCM studies in MGD, dry eye disease, systemic disease causing dry eye, dry eye in glaucoma patients, contact lens-associated ocular conditions, graft-versus-host disease, and Sjogren’s syndrome-related dry eye. The articles were identified through PubMed and a total number of 63 eligible publications were analyzed in detail. All primary research studies on confocal microscopy on dry eye and related conditions from 2017 onwards were included. The reports were reviewed for their contribution to the existing literature as well as potential biases and drawbacks. Despite limitations such as small field of view, lack of population-based norms, and lack of standardization of image acquisition, interpretation, and quantification, IVCM is useful as a complementary technique for clinical diagnosis in various ocular surface disorders related to dry eye. With advances in hardware and software in the near future, it has the potential for further practical impact.

Efficacy of the Systane iLux Thermal Pulsation System for the Treatment of Meibomian Gland Dysfunction After 1 Week and 1 Month: A Prospective Study

OBJECTIVES

To assess 1-week and 1-month efficacy of Systane iLux thermal pulsation treatment for meibomian gland dysfunction (MGD).

METHODS

This prospective, nonrandomized, open-label, multicenter study enrolled 30 adult patients (60 eyes) who had a Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire score greater than 6 and total meibomian gland secretion (MGS) score equal to or less than 12 in each eye. All participants received thermal pulsation treatment bilaterally. Primary efficacy measures included MGS score (sum of grades for 15 glands graded on a scale of 0-3; 0 [no secretion], 1 [inspissated], 2 [cloudy], and 3 [clear liquid]) and tear breakup time (TBUT). Secondary efficacy measures were SPEED and Ocular Surface Disease Index (OSDI) scores.

RESULTS

The mean age of patients was 52.9±11.9 years. After 1 week, the mean MGS score improved significantly from 4.1±3.1 to 15.8±7.1 (right eye, OD) and 3.7±3.1 to 16.7±7.6 (left eye, OS); mean TBUT improved significantly from 4.9±4.1 to 8.4±3.6 (OD) and 5.2±4.2 to 8.9±3.9 (OS); and mean SPEED and OSDI scores improved significantly from 16.1±5.3 to 7.2±6.1 and 45.2±21.3 to 19.0±16.8, respectively (all P<0.001). After 1 month, the mean MGS score improved to 18.3±8.2 (OD) and 18.6±7.3 (OS); mean TBUT improved to 9.7±3.8 (OD) and 9.6±3.5 (OS); and mean SPEED and OSDI scores improved to 7.0±5.6 and 16.7±14.5, respectively (all P<0.001). No adverse events were reported.

CONCLUSIONS

Systane iLux thermal pulsation treatment for MGD resulted in a statistically significant increase in meibomian gland secretion, improvement in tear film stability, and reduction in dry eye symptoms as early as both 1 week and 1 month.

Comparison Between Heated Eye Mask and Intense Pulsed Light Treatment for Contact Lens-Related Dry Eye

Background: Contact lens-related dry eye (CLDE) is common in contact lens (CL) wearers and can lead to ocular pain, decreased visual quality, and reduced quality of life. Objective: The purpose of this prospective, randomized, examiner masked study was to compare the effectiveness of intense pulsed light (IPL) and heated eye mask (HEM) for relieving CLDE. Methods: The final analysis included 60 patients (30 in the IPL group and 30 in the HEM group) who were using CL and had been suffering contact lens discomfort for more than a year. The IPL treatment group had two IPL treatments spaced 3 weeks apart, whereas the HEM group received HEM daily for 6 weeks (42 days). Non-invasive tear break-up time (NITBUT), tear-film lipid layer (TFLL), conjunctival fluorescein staining, meibum gland quality and expression, conjunctival redness score, ocular surface disease index (OSDI), best-corrected visual acuity, endothelial cell count, and intraocular pressure were assessed at baseline: first visit (V1), second visit (V2), and third visit (V3). Results: The mean age of the IPL group was 28.6 ± 4.3 years (16 females, 53%) and that of the HEM group was 28.6 ± 4.2 years (16 females, 53%). Mean NITBUT for the IPL group at V2 was 5.53 ± 0.77 sec (p < 0.001) and at V3 was 7.72 ± 0.88 sec (p < 0.001); the IPL group demonstrated a clinically and statistically significant improvement in mean NITBUT. In addition, the HEM group showed a clinically and statistically significant improvement in mean NITBUT at V3 (5.86 ± 0.76 sec, p < 0.001). At V3, the C-OSDI, TFLL score, and meibum gland quality and expressibility all increased considerably (p < 0.05) in both groups. Conclusions: Our results imply that IPL or HEM treatment of CLDE can be safely used to relieve symptoms of CLDE. In addition, IPL treatment is more effective in improving the general stability of the tear-film and decreasing the need for artificial tears in CLDE.

Demodex folliculorum Infestation in Meibomian Gland Dysfunction Related Dry Eye Patients

Objective

To report the influence of Demodex folliculorum (D. folliculorum) infestation in patients with meibomian gland dysfunction (MGD) related dry eye and the associations of the infestation with MGD related dry eye.

Methods

Eyelashes (three from the upper eyelid and three from the lower eyelid) from 119 eyes of 119 patients diagnosed with MGD related dry eye were examined under a light microscope. There were 68 eyes of 68 patients with MGD related dry eye and D. folliculorum infestation (Demodex positive group) and 51 eyes of 51 patients without infestation (Demodex negative group). All patients completed an Ocular Surface Disease Index (OSDI) questionnaire and underwent tests for dry eye and MGD. The tests included fluorescein tear breakup time (TBUT), corneal fluorescein staining, Schirmer I test (SIT), lid margin abnormalities, meibum expression assessment, and meibomian gland dropout.

Results

The scores for OSDI, corneal fluorescein staining, lid margin abnormalities, meibum expression, and meibomian gland dropout were significantly higher (all P &lt; 0.05), while TBUT was significantly shorter in the Demodex positive group compared to the Demodex negative group (P = 0.020). The SIT values did not significantly differ between groups. Chalazion was significantly more prevalent in the Demodex positive group. The number of D. folliculorum was positively correlated with all three MGD parameters (P ≤ 0.035), OSDI; corneal fluorescein scores, and it was inversely correlated with BUT. The correlation for SIT was R2 = 0.075 (P = 0.064).

Conclusion

Demodex folliculorum infestation is possibly one of the key contributors in the pathogenesis of MGD related dry eye, and a higher prevalence of chalazion was found in D. folliculorum infected patients. The possible causal role of D. folliculorum infestation needs to be further studied.

Measurements of Tear Evaporation Rate in Subjects with Refractive Errors Using a Portable Evaporimeter

Dry eye symptoms are associated with refractive errors. We aimed to measure the tear evaporation rate (TER) in subjects with refractive errors (RE) using a portable evaporimeter. This nonrandomized, case–control, and observational study included 75 subjects, including 25 subjects aged 18–38 years (28.8 ± 6.8 years) with myopia (−0.75 to −3.75 D) and 25 subjects aged 18–39 years (27.7 ± 5.5 years) with hyperopia (+0.50 to +3.75 D). In addition, a control group of 25 subjects with emmetropic eyes aged 20–30 years (23.6 ± 2.6 years) was recruited. The ocular surface disease index (OSDI) was completed, followed by the TER measurements using a portable evaporimeter. The OSDI score and TER measurements showed dry eye symptoms in 36% and 48% of myopic subjects, respectively. For hyperopic participants, dry eye was observed in 24% and 56% of the subjects based on the OSDI and TER scores, respectively. Significant differences (Mann-Whitney U test; p < 0.001) were found among the OSDI and TER scores recorded within the study (myopic and hyperopic subjects) and control groups. Significant strong positive correlations were detected between the OSDI and TER scores in both myopic (p = 0.004; r = 0.559) and hyperopic (p = 0.001; r = 0.619) subjects. The TER scores were significantly higher in subjects with RE (myopic and hyperopic) as compared with individuals with normal eyes.

Application of Animal Models in Interpreting Dry Eye Disease

Different pathophysiologic mechanisms are involved in the initiation, development, and outcome of dry eye disease (DED). Animal models have proven valuable and efficient in establishing ocular surface microenvironments that mimic humans, thus enabling better understanding of the pathogenesis. Several dry eye animal models, including lacrimal secretion insufficiency, evaporation, neuronal dysfunction, and environmental stress models, are related to different etiological factors. Other models may be categorized as having a multifactorial DED. In addition, there are variations in the methodological classification, including surgical lacrimal gland removal, drug-induced models, irradiation impairment, autoimmune antibody-induced models, and transgenic animals. The aforementioned models may manifest varying degrees of severity or specific pathophysiological mechanisms that contribute to the complexity of DED. This review aimed to summarize various dry eye animal models and evaluate their respective characteristics to improve our understanding of the underlying mechanism and identify therapeutic prospects for clinical purposes.

Sleep Quality Is Associated With Severe Meibomian Gland Disruption in Dry Eye

Purpose

To investigate the association between sleep quality and meibomian gland dropout characteristics in dry eye patients.

Methods

This cross-sectional study involved 172 dry eye patients with no history of conditions or factors that could confound dry eye disease (DED) and/or meibomian gland dropout. Participants underwent a comprehensive anterior eye assessment. The validated Athens Insomnia Scale (AIS) and Pittsburgh Sleep Quality Index (PSQI) were used to assess sleep quality. The measured outcomes were dry eye symptoms via the Ocular Surface Disease Index (OSDI), tear breakup time (TBUT), corneal fluorescein staining, meibomian gland function, and extent of meibomian gland dropout.

Results

Of the dry eye participants, 34.9% had severe meibomian gland dropout (SMD) and 41.3% of the subjects had poor sleep quality. Patients with poor sleep quality had greater Meibomian gland dropout while the sleep AIS and PSQI scores were significantly correlated with Meibomian gland dropout (r = 0.495, p &lt; 0.001; r = 0.24, p = 0.002; respectively). SMD patients had worse scores on all components of the PSQI (all p &lt; 0.001, corrected for age and sex). Use of sleep medication, poor habitual sleep efficiency, and sleep disturbance were particularly prevalent in SMD patients as compared to Non-severe meibomian gland dropout (NSMD) patients. Multivariate logistic regression analysis revealed that sleep quality was eventually associated with female gender (p = 0.042), OSDI (p = 0.004), TBUT (p = 0.036), and Meibomian gland dropout score (p &lt; 0.001).

Conclusion

It was found that greater meibomian gland dropout in poor sleep quality individuals is especially related to use of sleep medication, poor habitual sleep efficiency, and sleep disturbance. This finding suggests a need for long-term studies of anterior eye health in people with poor sleep quality.

Sodium hyaluronate combined with rhEGF contributes to alleviate clinical symptoms and Inflammation in patients with Xerophthalmia after cataract surgery

Background

To determine the effect of sodium hyaluronate combined with recombinant human epidermal growth factor (rhEGF) on clinical symptoms and inflammation in patients with newly diagnosed xerophthalmia after cataract surgery.

Methods

A total of 106 patients who underwent cataract surgery and were newly diagnosed with xerophthalmia in our hospital between June 2018 and August 2019 were enrolled. Of these, 50 patients who were treated with sodium hyaluronate (0.1%) were assigned to the monotherapy group (MG) and the remaining 56 patients who were treated with sodium hyaluronate (0.1%) combined with rhEGF (20 μg/ml) were assigned to the combination group (CG). The 2 groups were compared based on ocular surface disease index (OSDI) score, break-up time (BUT), fluorescein corneal staining level, Schirmer I test (SI) level, clinical efficacy (disappearance of typical symptoms, including eyes drying, burning sensation, foreign body sensation, etc), and interleukin (IL)-1, IL-6, and tumor necrosis factor-α (TNF-α) levels. Spearman correlation analysis was conducted to analyze the relationship between IL-1, IL-6, TNF-α and clinical efficacy. In addition, receiver operating characteristic curves were drawn to analyze the predictive value of IL-1, IL-6, and TNF-α in efficacy on xerophthalmia. Results: After treatment, the CG showed reduced OSDI score compared with the MG. The CG showed increased BUT (s) and SI (mm) levels compared with MG. After treatment, the CG exhibited decreased levels of IL-1(ng/mL), IL-6 (ng/mL), and TNF-α (ng/mL) compared with the MG. Spearman correlation analysis revealed that IL-1, IL-6, and TNF-α were negatively correlated with clinical efficacy. The areas under the curves of IL-1, IL-6, and TNF-α were 0.801, 0.800, and 0.736 respectively.

Conclusions

Sodium hyaluronate combined with rhEGF is helpful to alleviate clinical symptoms and inflammation in patients with xerophthalmia undergoing cataract surgery.

Metabolomics and lipidomics approaches in human tears: A systematic review

The human tear film is at the interface between the ocular surface and the external environment. Although investigation has been hindered by its small volume, improvements in preanalytical and analytical methods have allowed the omics approach to represent an innovative biomarker search strategy. There is still a significant lack of standardization, representing a barrier for performing between-studies comparisons and transferring experimental findings into clinical use and trials. We summarize the preanalytical and analytical procedures, describe the biomarkers that can be found using the metabo-lipidomics approach, and provide our expert opinion for omics investigations in human tears. For this systematic review of 38 studies, we searched PubMed by combining Boolean operators with the following keywords: tear, metabolomic, lipidomic, -omics. The human tear metabo-lipidome has been well-characterized in normal individuals using high-resolution liquid chromatography coupled with mass spectrometry. Lipid and metabolite profiles were influenced by ocular (e.g. dry eye disorders; Meibomian gland dysfunction; contact lens wear; glaucoma; keratoconus; pterygium) and systemic conditions (e.g. multiple sclerosis). Investigating the tear metabo-lipidome could improve our understanding of the pathogenesis of both ocular and systemic diseases, but also provide diagnostic as well as prognostic biomarkers.

Evaluation of Meibomian Gland Function after Therapy of Eyelid Tumors at Palpebral Margin with Super Pulse CO2 Laser

Purpose

To investigate the effect on meibomian gland function of super pulse carbon dioxide (CO₂) laser excision in the treatment of eyelid tumors at palpebral margin.

Methods

36 patients with 36 eyelid tumor size ≤ 1 cm and within 1 mm to palpebral margin were recruited in this study. Of which, 16 cases with tumors in the upper eyelid and 20 cases in the lower eyelid were involved. The eyelid tumors of all the patients were treated by super pulse CO₂ laser with its power density varied between 0.6 and 21.1 W/mm² and in repeat mode. The laser spot size ranged from 120 to 200 μm. Ocular surface parameters including tear film break-up time (BUT) and meibograde, meibum expressibility, and meibum quality were evaluated at pretherapy, 1 week, 1 month, and 3 months posttherapy in all 36 patients.

Result

All the patients were satisfied with the therapy. No infective complications and recurrence occurred in any of the 36 patients at the following period. The eyelid wound recovered well with nearly normal appearing after 2 to 3 weeks. The morphology of limbi palpebralis, BUT, meibograde, meibum expressibility, and meibum quality of all the 36 patients showed no significant difference before and after the therapy.

Conclusions

Super pulse CO₂ laser had no effect on meibomian gland function and morphology in the excision of tumors at palpebral margins, which was an efficacy and well-tolerated therapy with lower complications and recurrence.

Hyperglycemia Induces Meibomian Gland Dysfunction

Purpose

Patients diagnosed with diabetes are inclined to have abnormalities on stability of tear film and disorder of meibomian gland (MG). This study aims to explore the pathological change of MG induced by diabetes in a rat model.

Methods

Sprague-Dawley (SD) rats were intraperitoneally injected with streptozotocin (STZ) to establish a diabetic animal model. Lipid accumulation in MG was detected by Oil Red O staining and LipidTox staining. Cell proliferation status was determined by Ki67 and P63 immunostaining, whereas cell apoptosis was confirmed by TUNEL assay. Gene expression of inflammatory cytokines and adhesion molecules IL-1α, IL-1β, ELAM1, ICAM1, and VCAM1 were detected by RT-PCR. Activation of ERK, NF-κB, and AMPK signaling pathways was determined by Western Blot analysis. Oxidative stress-related factors NOX4, 4HNE, Nrf2, HO-1, and SOD2 were detected by immunostaining or Western Blot analysis. Tom20 and Tim23 immunostaining and transmission electron microscopy were performed to evaluate the mitochondria functional and structure change.

Results

Four months after STZ injection, there was acini dropout in MG of diabetic rats. Evident infiltration of inflammatory cells, increased expression of inflammatory factors, and adhesion molecules, as well as activated ERK and NF-κB signaling pathways were identified. Oxidative stress of MG was evident in 4-month diabetic rats. Phospho-AMPK was downregulated in MG of 2-month diabetic rats and more prominent in 4-month rats. After metformin treatment, phospho-AMPK was upregulated and the morphology of MG was well maintained. Moreover, inflammation and oxidative stress of MG were alleviated after metformin intervention.

Conclusions

Long-term diabetes may lead to Meibomian gland dysfunction (MGD). AMPK may be a therapeutic target of MGD induced by diabetes.

Mechanistic investigations of diabetic ocular surface diseases

With the global prevalence of diabetes mellitus over recent decades, more patients suffered from various diabetic complications, including diabetic ocular surface diseases that may seriously affect the quality of life and even vision sight. The major diabetic ocular surface diseases include diabetic keratopathy and dry eye. Diabetic keratopathy is characterized with the delayed corneal epithelial wound healing, reduced corneal nerve density, decreased corneal sensation and feeling of burning or dryness. Diabetic dry eye is manifested as the reduction of tear secretion accompanied with the ocular discomfort. The early clinical symptoms include dry eye and corneal nerve degeneration, suggesting the early diagnosis should be focused on the examination of confocal microscopy and dry eye symptoms. The pathogenesis of diabetic keratopathy involves the accumulation of advanced glycation end-products, impaired neurotrophic innervations and limbal stem cell function, and dysregulated growth factor signaling, and inflammation alterations. Diabetic dry eye may be associated with the abnormal mitochondrial metabolism of lacrimal gland caused by the overactivation of sympathetic nervous system. Considering the important roles of the dense innervations in the homeostatic maintenance of cornea and lacrimal gland, further studies on the neuroepithelial and neuroimmune interactions will reveal the predominant pathogenic mechanisms and develop the targeting intervention strategies of diabetic ocular surface complications.

Ocular Side Effects of Aromatase Inhibitor Endocrine Therapy in Breast Cancer - A Review

BACKGROUND

Aromatase inhibitor therapy is currently the preferred choice in postmenopausal women with estrogen receptor positive breast cancer. This article reviews the ocular side effects of treatment with aromatase inhibitors (AIs) in patients with breast cancer.

MATERIALS AND METHODS

A comprehensive search was performed on PubMed, Web of Science and Google scholar.

RESULTS

After duplication removal, 14 clinical studies and 5 case reports, published between 2008 and 2021, were identified. Most frequently, AI treatment resulted in minor to moderate dry eye symptoms. "De novo" onset of Sjogren syndrome during AI therapy was also reported. Retinal and optic nerve side effects varied from mild, subclinical anatomic and functional impairment to severe decreased vision, secondary to hemi-central retinal artery occlusion, bilateral optic neuritis or uveitis with bilateral macular edema.

CONCLUSION

Visual disturbances encountered during AI treatment may be underestimated. Ophthalmic screening is important for early detection and appropriate treatment.

Meibum sphingolipid composition is altered in individuals with meibomian gland dysfunction-a side by side comparison of Meibum and Tear Sphingolipids

PURPOSE

Sphingolipids (SPL) play a role in cell signaling, inflammation, and apoptosis. The purpose of this study was to examine meibum and tear SPL composition in individuals with poor versus good meibum quality.

METHODS

Individuals were grouped by meibum quality (n = 25 with poor quality, case group and n = 25 with good quality, control group). Meibum and tears were analyzed with liquid chromatography-mass spectrometry (LC-MS) to quantify SPL classes. Semiquantitative and relative composition (mole percent) of SPL and major classes, Ceramide (Cer), Hexosyl-Ceramide (Hex-Cer), Sphingomyelin (SM), Sphingosine (Sph), and sphingosine 1-phosphate (S1P) were compared between groups.

RESULTS

Demographic characteristics were similar between the two groups. Overall, individuals with poor meibum quality had more SPL pmole in meibum and tears than controls. Relative composition analysis revealed that individuals with poor meibum quality had SPL composed of less Cer, Hex-Cer, and Sph and more SM compared to individuals with good quality meibum. This pattern was not reproduced in tears as individuals with poor meibum quality had SPL composed of a similar amount of Cer, but more Hex-Cer, Sph and SM compared to controls. In meibum, SPL pmole and relative composition most strongly correlated with MG metrics while in tears, SPL pmole and relative composition most strongly correlated with tear production. SPL in both compartments, specifically Cer pmole in meibum and S1P% in tears, correlated with DE symptoms.

CONCLUSION

SPL composition differs in meibum and tears in patients with poor vs good meibum quality. These findings may be translated into therapeutic targets for disease.

MicroRNA Therapy for Dry Eye Disease

Purpose: We tested the role of microRNA-328 in dry eye disease (DED). Benzalkonium chloride (BAC) has been used to induce DED in animal models. We first demonstrated that both BAC and hyperosmotic stress induced overexpression of miR-328 in corneal cells and then tested whether anti-miR-328 could be a new therapy. Methods: BAC was instilled to both eyes of 41 rabbits and 19 mice from day 0 to 21 to induce DED. Animals of each species were divided to receive topical instillation of saline or anti-miR-328 eye drops between day 8 and 21. The DED signs were assessed by corneal fluorescein staining, histological examination, apoptosis of corneal cells, and inflammatory cytokines in rabbit eyes. For mice, only corneal fluorescein staining was assessed for the therapeutic effects. The corneal fluorescein staining scores ranged from 0 of no staining to 4 of coalescent. Results: For the rabbits, the staining score was significantly reduced (P = 0.038) after the 14-day anti-miR-328 treatment (n = 42 eyes), but the score was not improved by saline treatment (n = 40 eyes). Furthermore, rabbit eyes treated with anti-miR-328 had thicker corneal epithelium (P = 9.4 × 10^-5), fewer apoptotic cells in corneal epithelium (P = 0.002), and stroma (P = 0.029) compared with the saline-treated eyes. Anti-miR-328 was more effective than saline to reduce the block of orifices of Meibomian glands, although such an effect was only marginally significant (P = 0.059). Similarly, anti-miR-328 was more effective than saline in reducing corneal staining in mouse eyes (P = 0.005). Conclusion: Overexpression of miR-328 may contribute to DED. Anti-miR-328 protects corneal cells and promotes re-epithelialization for DED treatment.

Effect of ocular demodicosis on the stability of the tear film and the tear break up time

The aim of the study was to analyze the correlation between the presence of Demodex mites in the hair follicles of patients' eyelashes and the stability and break up time of the tear film assessed with the Non-Invasive Tear Break Up Times (NIBUT) method. 319 patients were included in the study (195 women, 124 men). The patients were divided into two groups: those with Demodex infestation and without visible symptoms of eyelid or eye surface diseases, and asymptomatic non-infested patients. The NIBUT analysis was performed with a 5 M keratograph (oculus). Non-invasive tests were performed to identify the first and mean values of the tear break up time. The first and mean tear break up time in the Demodex-infested group was lower than in the non-infested subjects. The difference was a highly statistically significant. There was a significant correlation with the age of the patients for the first break up time. The first break up time in both eyes decreased with the age of the Demodex-infested and non-infested patients. The NIBUT analyses indicate the impact of Demodex mites on the tear film stability. This may suggest possible association of demodicosis with dry eye syndrome.

Assessment of Tear Film Anomalies in Childhood Obesity

PURPOSE

To determine if childhood obesity has an effect on the ocular surface and tear film of children who are afflicted.

METHODS

Patients who had childhood obesity, 85 eyes, and patients who were healthy, 75 eyes, were enrolled in this prospective and comparative study. The tear film breakup time (TF-BUT), tear meniscus area and height (TMA and TMH) values, Schirmer test scores, and ocular surface disease index (OSDI) scores were obtained for all participants.

RESULTS

The TMH, TMA, TF-BUT, and Schirmer test results were statistically significantly lower in the obesity group (p < 0.001 for all). The children with obesity and insulin resistance had lower TMH, TMA, TF-BUT, and Schirmer test results when compared to the children without insulin resistance (p < 0.05 for all). The body mass index was found to be correlated with the TMH, TMA, TF-BUT, and Schirmer test results (p < 0.001 for all).

CONCLUSION

Children with obesity had lower TMA, TMH, TF-BUT, and Schirmer test results than healthy subjects. When insulin resistance was added to obesity, these values were even lower.

Video display terminal use and other risk factors for abnormal blinking in children: gender differences

OBJECTIVE

To explore the risk factors for abnormal blinking in children and compare these between boys and girls.

METHODS

Children attending the Children's Optometry Clinic between June 2019 and June 2020 were recruited for the study. The time they had spent viewing video displays (VDTt) over the past 6 months was recorded. Incomplete blinking (IB) and blinking rate were measured and all participants were allocated to groups based on their blink rate (<20 times/min = normal blinking group, NBG; ≥20 times/min = abnormal blinking group, ABG). Tear film (TF) stability was also evaluated. The corresponding statistical methods are used to analyze the data.

RESULTS

A total of 87 boys and 80 girls were enrolled in the study. No significant difference in age was found between the 2 groups. There was a significant difference in TF stability between the two groups (P<0.05). According to binary logistic analysis, VDTt and ocular protection index (OPI) are important risk factors for abnormal blinking, with cut-off values of 1.75 hours and 1.014 respectively in boys; and 1.25 hours and 1.770 respectively in girls. The average of lipid layer thickness was an important protective factor for children using VDT for long periods, with a cut-off value of 58.5 nm in boys and 53.5nm in girls.

CONCLUSION

Risk factors for abnormal blinking in both boys and girls include VDTt and OPI.

Meibomian gland dysfunction is highly prevalent among first-time visitors at a Norwegian dry eye specialist clinic

To investigate the prevalence of meibomian gland dysfunction (MGD) in patients presenting with subjective dry eye-related symptoms at their first-time consultation in a Norwegian specialized ocular surface clinic. Additionally, to explore the accuracy of the ocular surface disease index score (OSDI) as an extensively applied tool to assess the severity of dry eye symptoms and MGD diagnosis. Patients with subjective dry eye-related complaints (n = 900) attending the clinic for the first time, from 2012 to 2016, were included in the study. At the baseline, patients completed the OSDI questionnaire. Subsequently, objective clinical tests, including fluorescein break-up time (FBUT), Schirmer-I test, ocular surface staining (OSS), and meibomian gland function assessment using gland expressibility and meibum quality were performed. The association between MGD and its severity in relation to symptom severity defined by OSDI-score was examined. MGD was found in 93.8% of the study group. MGD prevalence was not significantly different between groups based on age (p = 0.302) or sex (p = 0.079). There was a significant association between severity of MGD and dry eye-related symptoms (p = 0.014). OSS was significantly higher in patients with severe symptoms (p = 0.031). Sensitivity and specificity of positive symptom-score (OSDI ≥ 13) for disclosing MGD were 85.5% and 30.4%, respectively. MGD was highly prevalent, not associated with age and sex. OSDI ≥ 13 had high sensitivity and high positive predictive value (PPV), but low specificity and negative predictive value (NPV) for disclosing MGD. This underscores the importance of meibomian gland assessment in patients with dry eye-related symptoms.

Effects of Vectored Thermal Pulsation on Objective Tear Film Measures

PURPOSE

To assess the effect of vectored thermal pulsation treatment for meibomian gland dysfunction on objective measures of lipid layer thickness (LLT) and tear osmolarity.

METHODS

One hundred patients with meibomian gland dysfunction diagnosis were recruited to participate. At their initial visit, baseline study parameters were recorded, and vectored thermal pulsation treatment was administered. At the 2- to 3-month follow-up visit, the study parameters were reevaluated. Subjective symptoms were evaluated using the Ocular Surface Disease Index questionnaire. LLT was measured using an ocular surface interferometer. Tear osmolarity was calculated using impedance measurement of tear fluid collected from the eyelid margin.

RESULTS

Ninety-six patients (192 eyes) completed the follow-up. Mean improvement in Ocular Surface Disease Index was 5.6 points (95% confidence interval [CI], -9.0 to -2.1, P = 0.002). There was no significant change in tear osmolarity (mean change -1.6 mOsm/L, 95% CI, -4.7 to +1.3 mOsm/L, P = 0.3). There was no significant change in LLT (mean change -4.3 nm, 95% CI, -9.1 to +0.5 nm, P = 0.08).

CONCLUSIONS

The hypothesis that vectored thermal pulsation treatment would decrease tear osmolarity and increase LLT was not substantiated. Although we detected significant improvement in subjective symptoms, the improvement was smaller than the improvements reported in previous studies. Our results suggest that the current understanding of the effects of vectored thermal pulsation treatment is incomplete.

Evaluation of ocular psoriasis with meibography

Background

Previous studies has shown that dry eye test abnormalities, meibomian gland dysfunction (MGD), may occur in psoriasis.

Objectives

The authors aimed to evaluate the dry eye disease (DED), MGD, in psoriasis patients with meibography which is a current, objective, noninvasive method for patients with meibomian gland diseases, to investigate the relationship between disease severity and ocular involvement.

Methods

This study included 50 participants with psoriasis and 50 healthy individuals. All subjects were examined by the same dermatologist and referred for ophthalmological examination including meibomian gland obstruction, lid margin alterations assessment, ocular surface disease index assessment, tear film break-up time test, Schirmer test, corneal conjunctival fluorescein staining assessment. Additionally, upper and lower lids were evaluated for meibomian gland loss with meibography.

Results

MGD (28%), meibomian gland loss (MGL) (29.5%), upper meiboscore (0.61 ± 0.81), lower meiboscore (0.46 ± 0.61), DED (22%) were significantly higher in the psoriasis group compared with the control group (p = 0.008, p < 0.001, p = 0.027, p = 0.041, p = 0.044, respectively). There was a significant relationship between MGD and psoriasis area severity index (PASI) (p = 0.015, Odds Ratio = 1.211). There was a significant positive relationship between MGL with PASI (p < 0.001, r = 608) and psoriasis duration (p < 0.001, r = 0.547).

Study limitations

Smaller study group and inability to detect quality changes of meibum with meibography were limitations of the study.

Conclusions

Psoriasis may affect the meibomian gland morphology, may cause structural changes in meibomian glands, and as a result of these may cause MGD and DED. Therefore, ophthalmologists and dermatologists should be aware of this situation and co-evaluate the patients in this respect.

The Correlation Between Non-Invasive Ventilation Use and the Development of Dry Eye Disease

The use of non-invasive ventilation (NIV) devices such as continuous positive airway pressure and bi-level positive airway pressure machines have been associated with an increased incidence of dry eye disease (DED). To understand how the use of these ventilation masks impacts the eyes, a review of the pathophysiology of DED and an evaluation of recent studies investigating the effects of NIV use on the severity and incidence of this condition were performed. It was found that the use of face masks associated with the ventilation devices exhibited a positive correlation to the incidence and severity of numerous ocular pathologies. However, the benefits of non-invasive mechanical ventilation are undeniable in treating conditions such as obstructive sleep apnea, chronic obstructive pulmonary disease, and respiratory failure; therefore, proper education, behavioral modifications, and treatment can help reduce or prevent the adverse effects that NIV have on the eyes.

The Effect and the Mechanism of Comprehensive Treatment on the Ocular Surface and the Visual Quality of Online Teachers with a Mild-to-Moderate Dry Eye Condition During the Early Phase of Coronavirus Disease 2019

Objective

To investigate the effect of comprehensive treatment on ocular surface function and the visual quality of online teachers with a mild-to-moderate dry eye condition during the early phase of coronavirus disease 2019 (COVID-19).

Methods

Secondary school online teachers diagnosed with a mild-to-moderate dry eye disease in our outpatient clinic from February to May 2020 were enrolled in this retrospective cross-section study, and all patients received dry eye comprehensive treatment. A questionnaire survey on eye-use habits, visual quality and dry eye-related indicators was collected before and after treatment (2 and 4 weeks). The changes and the correlations between indicators before and after treatment were compared.

Results

A total of 30 patients (15 females and 15 males) were included. After comprehensive treatment, patients had significantly higher central tear meniscus height (TMH), non-invasive first tear film breakup time (NIBUTf) and non-invasive average tear film breakup time (NIBUTav) than those before with statistical significance (P < 0.05). Lower ocular surface disease index (OSDI) and Meibomian gland scores were observed after treatment with statistical significance (P < 0.05). Objective scatter index (OSI), modulation transfer function (MTF) cutoff, strehl ratio (SR), and tear film objective scatter index (TF-OSI) were significantly improved after treatment (P < 0.05). Besides, TF-OSI was positively correlated with the changes in OSDI, Meibomian gland score, eye-use duration and OSI with statistical significance (P < 0.05), while it was negatively correlated with NIBUTf, NIBUTav, the TMH of the central lower eyelid, SR, sleep duration, conjunctival congestion and the MTF cutoff (P < 0.05), respectively. No correlation between TF-OSI and ciliary congestion was found (P > 0.05).

Conclusion

Comprehensive treatment could effectively improve the symptoms and visual quality of online teachers with a mild-to-moderate dry eye condition during the early stage of COVID-19 pandemic.

Epithelial stem cell homeostasis in Meibomian gland development, dysfunction, and dry eye disease

Dry eye disease affects over 16 million adults in the US, and the majority of cases are due to Meibomian gland dysfunction. Unfortunately, the identity of the stem cells involved in Meibomian gland development and homeostasis is not well elucidated. Here, we report that loss of Krox20, a zinc finger transcription factor involved in the development of ectoderm-derived tissues, or deletion of KROX20-expressing epithelial cells disrupted Meibomian gland formation and homeostasis, leading to dry eye disease secondary to Meibomian gland dysfunction. Ablation of Krox20-lineage cells in adult mice also resulted in dry eye disease, implicating Krox20 in homeostasis of the mature Meibomian gland. Lineage-tracing and expression analyses revealed a restricted KROX20 expression pattern in the ductal areas of the Meibomian gland, although Krox20-lineage cells generate the full, mature Meibomian gland. This suggests that KROX20 marks a stem/progenitor cell population that differentiates to generate the entire Meibomian gland. Our Krox20 mouse models provide a powerful system that delineated the identity of stem cells required for Meibomian gland development and homeostasis and can be used to investigate the factors underlying these processes. They are also robust models of Meibomian gland dysfunction-related dry eye disease, with a potential for use in preclinical therapeutic screening.

Focused ultrasound stimulation on meibomian glands for the treatment of evaporative dry eye

Current treatments for meibomian gland dysfunction have several limitations, creating a necessity for other advanced treatment options. The purpose of this study is to determine the effectiveness of focused ultrasound stimulation for the treatment of dry eye disease caused by meibomian gland dysfunction. An in vivo study of nine Dutch Belted rabbits was conducted with focused ultrasound stimulation of the meibomian glands. A customized line-focused ultrasonic transducer was designed for treatment. Fluorescein imaging, Schirmer's test, and Lipiview II ocular interferometer were used to quantify outcomes from three aspects: safety, tear production, and lipid layer thickness. Both tear secretion and lipid layer thickness improved following ultrasound treatment. Five to 10 min after the ultrasound treatment, the mean values of lipid layer thickness increased from 55.33 ± 11.15 nm to 95.67 ± 22.77 nm (p < 0.05), while the mean values measured with the Schirmer's test increased from 2.0 ± 2.3 to 7.2 ± 4.3 (p < 0.05). Positive effects lasted more than three weeks. Adverse events such as redness, swelling, and mild burn, occurred in two rabbits in preliminary experiments when the eyelids sustained a temperature higher than 42°C. No serious adverse events were found. The results suggest that ultrasound stimulation of meibomian glands can improve both tear production and lipid secretion. Ultimately, ultrasound stimulation has the potential to be an option for the treatment of evaporative dry eye disease caused by meibomian gland dysfunction.