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Ophthalmology Nov 2017To discuss the pathology, causes, and ocular surface impact of meibomian gland disease (MGD), as well as its relationship to dry eye. (Review)
Review
TOPIC
To discuss the pathology, causes, and ocular surface impact of meibomian gland disease (MGD), as well as its relationship to dry eye.
CLINICAL RELEVANCE
MGD is a common disorder with various contributing mechanisms and clinical manifestations. Understanding MGD pathophysiology and its relationship to dry eye is important in order to optimize diagnosis and treatment algorithms.
METHODS
A review of current literature was performed to discern MGD in terms of pathophysiology, risk factors, and ocular surface impact, and the relationship to dry eye.
RESULTS
Meibomian gland obstruction and meibocyte depletion are important components of MGD. Many pathologies can disrupt function of meibomian glands, ranging from congenital to acquired causes. Once gland disruption occurs, the quality and quantity of meibum is altered, with a negative impact on the ocular surface. Increased tear evaporation, tear hyperosmolarity, increased ocular surface staining, increased inflammation, symptomatic irritation of the eyelid and globes, as well as decreased visual acuity have all been observed.
CONCLUSION
MGD leads to changes in meibum quality and quantity that can cause evaporative dry eye and ocular surface disruption, leading to dry eye symptoms in some individuals.
Topics: Animals; Dry Eye Syndromes; Eyelid Diseases; Humans; Meibomian Glands
PubMed: 29055358
DOI: 10.1016/j.ophtha.2017.05.031 -
Hong Kong Medical Journal = Xianggang... Feb 2019Dry eye disease is one of the most common ophthalmic complaints; it results from the activity of various pathways and is considered a multifactorial disease. An... (Review)
Review
Dry eye disease is one of the most common ophthalmic complaints; it results from the activity of various pathways and is considered a multifactorial disease. An important factor that contributes to the onset of dry eye disease is meibomian gland dysfunction. Meibomian gland dysfunction causes a disruption in the tear film lipid layer which affects the rate of tear evaporation. This evaporation leads to tear hyperosmolarity, eventually triggering the onset of dry eye disease. Dry eye disease and meibomian gland dysfunction are strongly associated with each other, such that many of their risk factors, signs, and symptoms overlap. This review aimed to provide an update on the association between dry eye disease and meibomian gland dysfunction. A stepwise approach for diagnosis and management is summarised.
Topics: Diagnostic Imaging; Dry Eye Syndromes; Eyelid Diseases; Fluorescent Dyes; Humans; Meibomian Glands; Randomized Controlled Trials as Topic; Risk Factors; Slit Lamp; Staining and Labeling; Tears
PubMed: 30713149
DOI: 10.12809/hkmj187331 -
The Ocular Surface Oct 2020To review the published literature related to application of intense pulsed light (IPL) for treating meibomian gland dysfunction (MGD). (Review)
Review
PURPOSE
To review the published literature related to application of intense pulsed light (IPL) for treating meibomian gland dysfunction (MGD).
METHODS
The literature search included the PubMed database and used the keywords "Intense Pulsed Light and Meibomian Gland Dysfunction".
RESULTS
IPL is a new instrumental treatment modality for MGD. This treatment modality was originally developed for use in dermatology and was later adopted in ophthalmology for treating MGD. IPL therapy for MGD can improve tear film stability, meibomian gland functionality, as well as subjective feeling of ocular dryness. However, in the reviewed literature, there was great variability in patient selection, evaluation criteria, and treatment protocols and durations.
CONCLUSION
Numerous studies report that IPL is effective for treating MGD and a safe procedure. There is great potential for further improvements to the procedure, as large comparative studies employing different treatment modalities are lacking.
Topics: Humans; Intense Pulsed Light Therapy; Meibomian Gland Dysfunction; Meibomian Glands; Ophthalmology; Tears
PubMed: 32629039
DOI: 10.1016/j.jtos.2020.06.002 -
Investigative Ophthalmology & Visual... Jan 2022Patients 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...
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.
Topics: Animals; Blood Glucose; Cytokines; Disease Models, Animal; Hyperglycemia; Male; Meibomian Gland Dysfunction; Meibomian Glands; Oxidative Stress; Rats; Rats, Sprague-Dawley; Signal Transduction
PubMed: 35072689
DOI: 10.1167/iovs.63.1.30 -
Survey of Ophthalmology 2022The human tear film is at the interface between the ocular surface and the external environment. Although investigation has been hindered by its small volume,... (Review)
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.
Topics: Biomarkers; Dry Eye Syndromes; Humans; Lipidomics; Meibomian Glands; Metabolomics; Tears
PubMed: 35093405
DOI: 10.1016/j.survophthal.2022.01.010 -
Clinical & Experimental Optometry Jul 2021Dry eye disease is one of the most common, chief-complaints presenting in clinical practice, with a prevalence of up to 50%. Evaporative dry eye, as a result of...
Dry eye disease is one of the most common, chief-complaints presenting in clinical practice, with a prevalence of up to 50%. Evaporative dry eye, as a result of meibomian gland dysfunction, is thought to be the biggest component factor. Treatments for meibomian gland dysfunction aim to restore tear film homoeostasis and include warm compress therapy, eyelid hygiene, in-office meibomian gland expression and lipid-containing, artificial tears. A recent introduction to the in-office treatments available for meibomian gland dysfunction has been low-level light therapy, also known as photobiomodulation. The technique involves applying red, or near infra-red, radiation using low-power light sources and is suggested to promote tissue repair, decrease inflammation, and relieve pain. This work aims to review the available literature on the efficacy and safety of photobiomodulation in meibomian gland dysfunction and dry eye disease, as well as what is currently known about its mechanism of action.
Topics: Dry Eye Syndromes; Eyelid Diseases; Humans; Low-Level Light Therapy; Meibomian Gland Dysfunction; Meibomian Glands; Tears
PubMed: 33689636
DOI: 10.1080/08164622.2021.1878866 -
International Journal of Molecular... Jun 2017Dry eye can damage the ocular surface and result in mild corneal epithelial defect to blinding corneal pannus formation and squamous metaplasia. Significant progress in... (Review)
Review
Dry eye can damage the ocular surface and result in mild corneal epithelial defect to blinding corneal pannus formation and squamous metaplasia. Significant progress in the treatment of dry eye has been made in the last two decades; progressing from lubricating and hydrating the ocular surface with artificial tear to stimulating tear secretion; anti-inflammation and immune regulation. With the increase in knowledge regarding the pathophysiology of dry eye, we propose in this review the concept of ocular surface microenvironment. Various components of the microenvironment contribute to the homeostasis of ocular surface. Compromise in one or more components can result in homeostasis disruption of ocular surface leading to dry eye disease. Complete evaluation of the microenvironment component changes in dry eye patients will not only lead to appropriate diagnosis, but also guide in timely and effective clinical management. Successful treatment of dry eye should be aimed to restore the homeostasis of the ocular surface microenvironment.
Topics: Cellular Microenvironment; Conjunctiva; Cornea; Dry Eye Syndromes; Eye; Eyelids; Homeostasis; Hormones; Humans; Lacrimal Apparatus; Lubricant Eye Drops; Meibomian Glands; Microbiota; Tears
PubMed: 28661456
DOI: 10.3390/ijms18071398 -
Tidsskrift For Den Norske Laegeforening... Aug 2019Dry eye disease is a frequent reason for patients to seek help. In our experience, it is an underdiagnosed and undertreated condition. (Review)
Review
Dry eye disease is a frequent reason for patients to seek help. In our experience, it is an underdiagnosed and undertreated condition.
Topics: Dry Eye Syndromes; General Practitioners; Humans; Meibomian Glands; Ophthalmologists; Optometrists
PubMed: 31429248
DOI: 10.4045/tidsskr.18.0752 -
Experimental Eye Research Oct 2017Meibum is a lipid-rich secretion that is produced by fully differentiated meibocytes in the holocrine Meibomian glands (MG) of humans and most mammals. The secretion is... (Review)
Review
Meibum is a lipid-rich secretion that is produced by fully differentiated meibocytes in the holocrine Meibomian glands (MG) of humans and most mammals. The secretion is a part of a defense mechanism that protects the ocular surface from hazardous environmental factors, and from desiccation. Meibomian lipids that have been identified in meibum are very diverse and unique in nature. The lipid composition of meibum is different from virtually any other lipid pool found in the human body. In fact, meibum is quite different from sebum, which is the closest secretion that is produced by anatomically, physiologically, and biochemically related sebaceous glands. However, meibum of mice have been shown to closely resemble that of humans, implying similar biosynthetic mechanisms in MG of both species. By analyzing available genomic, immunohistochemical, and lipidomic data, we have envisioned a unifying network of enzymatic reactions that are responsible for biosynthesis of meibum, which we call meibogenesis. Our current theory is based on an assumption that most of the biosynthetic reactions of meibogenesis are catalyzed by known enzymes. However, the main features that make meibum unique - the ratio of identified classes of lipids, the extreme length of its components, extensive ω-hydroxylation of fatty acids and alcohols, iso- and anteiso-branching of meibomian lipids (e.g. waxes), and the presence of rather unique complex lipids with several ester bonds - make it possible that either the activity of known enzymes is altered in MG, or some unknown enzymes contribute to the processes of meibogenesis, or both. Studies are in progress to elucidate meibogenesis on molecular level.
Topics: Bodily Secretions; Humans; Lipid Metabolism; Lipids; Meibomian Glands; Tears
PubMed: 28669846
DOI: 10.1016/j.exer.2017.06.020 -
Indian Journal of Ophthalmology Apr 2023Evaporative dry eye (EDE) due to meibomian gland dysfunction (MGD) is one of the common clinical problems encountered in ophthalmology. It is a major cause of dry eye... (Review)
Review
Evaporative dry eye (EDE) due to meibomian gland dysfunction (MGD) is one of the common clinical problems encountered in ophthalmology. It is a major cause of dry eye disease (DED) and of ocular morbidity. In EDE, inadequate quantity or quality of lipids produced by the meibomian glands leads to faster evaporation of the preocular tear film and symptoms and signs of DED. Although the diagnosis is made using a combination of clinical features and special diagnostic test results, the management of the disease might be challenging as it is often difficult to distinguish EDE from other subtypes of DED. This is critical because the approach to the treatment of DED is guided by identifying the underlying subtype and cause. The traditional treatment of MGD consists of warm compresses, lid massage, and improving lid hygiene, all measures aimed at relieving glandular obstruction and facilitating meibum outflow. In recent years, newer diagnostic imaging modalities and therapies for EDE like vectored thermal pulsation and intense pulsed light therapy have emerged. However, the multitude of management options may confuse the treating ophthalmologist, and a customized rather than a generalized approach is necessary for these patients. This review aims to provide a simplified approach to diagnose EDE due to MGD and to individualize treatment for each patient. The review also emphasizes the role of lifestyle modifications and appropriate counseling so that patients can have realistic expectations and enjoy a better quality of life.
Topics: Humans; Meibomian Gland Dysfunction; Quality of Life; Meibomian Glands; Dry Eye Syndromes; Tears
PubMed: 37026266
DOI: 10.4103/IJO.IJO_2841_22