Ocular Evaporation in Meibomian Gland Dysfunction and Dry Eye
Background: Secretions from the meibomian gland are believed to be important in reducing ocular surface water evaporation and preventing dry eye. Patients with blepharitis frequently have meibomian gland dysfunction with loss of meibomian glands (drop out). The authors hypothesized that dry eye that often occurs in patients with chronic blepharitis is secondary to increased evaporation associated with gland loss.
Methods: The authors measured the ocular surface water evaporation and tear osmolarity of patients with meibomian gland drop out and patients with gland drop out with a low Schirmer test. These findings were compared with those of a control group.
Results: The authors found that eyes with meibomian gland drop out and those with drop out and a low Schirmer test had a significantly higher evaporative rate at 30% relative humidity (average, 49.9 ± 21 × 10-7 g/cm2/second, or 0.49 ± 0.29 μl/minute evaporative loss per eye, and 59.1 ± 28 × 10-7 g/cm2/second, or 0.58 ± 0.23 μl/minute, respectively) when compared with those in the control group (average, 14.8 + 6 × 10-7 g/cm2/second, or 0.15 ± 0.07 μl/minute [P Ã 0.05]). There was a significant correlation between evaporative rate and gland drop out (r = 0.522).
Conclusion: Patients with meibomian gland drop out, and especially those with low tear production by Schirmer test, have an increased risk of dry eye developing through increased evaporation.
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Cited by (280)
The Yin and Yang of non-immune and immune responses in meibomian gland dysfunction
2024, Ocular SurfaceMeibomian gland dysfunction (MGD) is a leading cause of dry eye disease and one of the most common ophthalmic conditions encountered in eye clinics worldwide. These holocrine glands are situated in the eyelid, where they produce specialized lipids, or meibum, needed to lubricate the eye surface and slow tear film evaporation – functions which are critical to preserving high-resolution vision. MGD results in tear instability, rapid tear evaporation, changes in local microflora, and dry eye disease, amongst other pathological entities. While studies identifying the mechanisms of MGD have generally focused on gland obstruction, we now know that age is a major risk factor for MGD that is associated with abnormal cell differentiation and renewal. It is also now appreciated that immune-inflammatory disorders, such as certain autoimmune diseases and atopy, may trigger MGD, as demonstrated through a T cell-driven neutrophil response. Here, we independently discuss the underlying roles of gland and immune related factors in MGD, as well as the integration of these two distinct mechanisms into a unified perspective that may aid future studies. From this unique standpoint, we propose a revised model in which glandular dysfunction and immunopathogenic pathways are not primary versus secondary contributors in MGD, but are fluid, interactive, and dynamic, which we likened to the Yin and Yang of MGD.
Tear-film evaporation flux and its relationship to tear properties in symptomatic and asymptomatic soft-contact-lens wearers
2023, Contact Lens and Anterior EyeWith soft-contact-lens wear, evaporation of the pre-lens tear film affects the osmolarity of the post-lens tear film and this can introduce a hyperosmotic environment at the corneal epithelium, leading to discomfort. The purposes of the study are to ascertain whether there are differences in evaporation flux (i.e., the evaporation rate per unit area) between symptomatic and asymptomatic soft-contact-lens wearers, to assess the repeatability of a flow evaporimeter, and to assess the relationship between evaporation fluxes, tear properties, and environmental conditions.
Closed-chamber evaporimeters commonly used in ocular-surface research do not control relative humidity and airflow, and, therefore, misestimate the actual tear-evaporation flux. A recently developed flow evaporimeter overcomes these limitations and was used to measure accurate in-vivo tear-evaporation fluxes with and without soft-contact-lens wear for symptomatic and asymptomatic habitual contact-lens wearers. Concomitantly, lipid-layer thickness, ocular-surface-temperature decline rate (i.e., °C/s), non-invasive tear break-up time, tear-meniscus height, Schirmer tear test, and environmental conditions were measured in a 5 visit study.
Twenty-one symptomatic and 21 asymptomatic soft-contact-lens wearers completed the study. A thicker lipid layer was associated with slower evaporation flux (p < 0.001); higher evaporation flux was associated with faster tear breakup irrespective of lens wear (p = 0.006). Higher evaporation flux was also associated with faster ocular-surface-temperature decline rate (p < 0.001). Symptomatic lens wearers exhibited higher evaporation flux than did asymptomatic lens wearers, however, the results did not reach statistical significance (p = 0.053). Evaporation flux with lens wear was higher than without lens wear but was also not statistically significant (p = 0.110).
The repeatability of the Berkeley flow evaporimeter, associations between tear characteristics and evaporation flux, sample-size estimates, and near statistical significance in tear-evaporation flux between symptomatic and asymptomatic lens wearers all suggest that with sufficient sample sizes, the flow evaporimeter is a viable research tool to understand soft-contact-lens wear comfort.
Meibomian gland stem/progenitor cells: The hunt for gland renewal
2023, Ocular SurfaceMeibomian glands (MGs) secrete lipid (meibum) onto the ocular surface to form the outermost layer of the tear film. Proper meibum secretion is essential for stabilizing the tear film, reducing aqueous tear evaporation, and maintaining the homeostasis of the ocular surface. Atrophy of MG as occurs with aging, leads to reduction of meibum secretion, loss of ocular surface homeostasis and evaporative dry eye disease (EDED). Since MGs are holocrine glands, secretion of meibum requires continuous self-renewal of lipid-secreting acinar meibocytes by stem/progenitor cells, whose proliferative potential is dramatically reduced with age leading to MG atrophy and an age-related meibomian gland dysfunction (ARMGD). Understanding the cellular and molecular mechanisms regulating meibocyte stem/progenitor cell maintenance and renewal may provide novel approaches to regenerating MG and treating EDED. Towards that end, recent label retaining cell and lineage-tracing experiments as well as knock-out transgenic mouse studies have begun to identify the location and identities of meibocyte progenitor cells and potential growth and transcription factors that may regulate meibocyte renewal. In addition, recent reports have shown that ARMGD may be reversed by novel therapeutics in mice. Herein, we discuss our current understanding of meibocyte stem/progenitor cells and the hunt for gland renewal.
Anterior blepharitis is associated with elevated plectin levels consistent with a pronounced intracellular response
2023, Ocular SurfaceAnterior blepharitis is a frequent ocular condition which may result in severe ocular surface disease. In this study, advanced proteome analysis was performed to elucidate biological mechanisms underlying anterior blepharitis.
All patients underwent full ophthalmological examination including Ocular Surface Disease Index score (OSDI). Measurement of non-invasive break-up time (NBUT), Oxford score, and meibography were performed. Tear film samples from treatment naïve patients with anterior blepharitis (n = 15) and age-matched controls (n = 11) were collected with Schirmer filtration paper. The samples were analyzed with label-free quantification nano liquid chromatography - tandem mass spectrometry (LFQ nLC-MS/MS). Significantly regulated proteins were identified with a permutation-based calculation with a false discovery rate at 0.05.
Among the 927 proteins detected, a total of 162 proteins were significantly changed. Regulated proteins were involved in cytoplasmic translation, positive regulation of B cell activation, complement activation and phagocytosis. High levels of plakin proteins, a group of proteins involved in cytoskeleton organization, were observed in anterior blepharitis, including plectin, desmoplakin, envoplakin, epiplakin, periplakin, and vimentin. The upregulation of plectin was confirmed with single reaction monitoring. Patients with anterior blepharitis had lower levels of immunoglobulin chains, VEGF coregulated chemokine 1 (CXCL17), and platelet-derived growth factor C.
Anterior blepharitis was associated with a high level of plectin indicating a pronounced intracellular response with cytoskeletal reorganization. Our data suggest a lack of immunoglobulin chains and CXCL17 in anterior blepharitis with potential alterations in the ocular surface immune response.
The lowly chalazion
2023, Survey of OphthalmologyChalazia are localized cysts of chronic lipogranulomatous inflammation arising from the obstruction of sebaceous glands of the eyelid tarsal plate, including the Meibomian gland (deep chalazion) or Zeis gland (superficial chalazion). This disease entity is differentiated from the hordeolum (stye), an acute purulent localized swelling of the eyelid often associated with an eyelash follicle, Zeis gland, or Moll gland obstruction and infection. Ambiguously, the chalazion, hordeolum, and blepharitis are commonly categorized and described on a continuum in the literature. While it is one of the most common eyelid disorders across all age demographics, the chalazion remains largely understudied and pathophysiological, epidemiological, and therapeutic findings exist fragmented in the literature. We discuss current understandings of the chalazion and provide current best practice guidelines supported by clinical anecdotal evidence.
Optimized combined low level light therapy and intense pulsed light therapy for the treatment of dry eye syndrome caused by Meibomian glands dysfunction
2022, Journal Francais d'OphtalmologieDry eye syndrome (DES) is a common disease that can lead to ocular discomfort, reduced visual acuity and reduced quality of life. Meibomian Gland dysfunction plays an important role in most cases. To evaluate the effects of “EyeLight”, a novel device delivering combined intense pulsed light (IPL) and low-level light therapy (LLLT), we conducted a retrospective chart review of patients refractory to conventional medical treatment who were treated with “EyeLight” therapy at Laser Vision, Lebanon. Each patient received between 2 to 5 treatment sessions. Clinical measurements were obtained before and after each session, including tear film breakup time (TBUT), ME-CHECK-meiboscale and the ME-CHECK questionnaire to determine the need for an additional session and to monitor progress. The same clinical evaluation was performed 3 to 5 weeks after the final treatment. A total of 52 eyes were included. A significant improvement in objective clinical signs was found, with an increase in TBUT from 6.98 ± 1.41s. to 9.27 ± 1.25s. (P < 0.001) and a decrease in ME-CHECK-meiboscale (P < 0.001). A reduction of severity level on the ME-CHECK-meiboscale classification was observed in 90%, along with a significant improvement in subjective clinical signs on the ME-CHECK questionnaire (P < 0.001). No ocular or facial adverse events were noted. “EyeLight” treatment of 2 to 5 sessions depending on the severity of MGD in each eye showed an improvement in objective clinical signs and subjective symptoms and therefore appears to be an effective treatment for DES related to MGD refractory to conventional treatment.
Le syndrome de l’œil sec (SOS) est une affection courante pouvant entraîner une gêne oculaire, une diminution de l’acuité visuelle et de la qualité de vie. Le dysfonctionnement des glandes de Meibomius (MGD) y joue un rôle majeur. Pour évaluer les effets de « EyeLight », un nouveau dispositif combinant les thérapies par la lumière pulsée intense (IPL) et la lumière laser de bas-niveau (LLLT), nous avons effectué une revue rétrospective des dossiers de patients ayant un SOS réfractaire aux traitements médicaux conventionnels, traités par « EyeLight » à LaserVision, Liban. Chaque patient a reçu entre 2 et 5 séances. Des mesures cliniques ont été effectuées avant et après chacune des séances en utilisant le temps de rupture des larmes (TBUT), l’échelle ME-CHECK-meiboscale et le questionnaire ME-CHECK pour déterminer la nécessité d’une séance supplémentaire et suivre les progrès. La même évaluation a été faite 3 à 5 semaines après le dernier traitement. Cinquante-deux yeux ont été inclus. Une amélioration significative des signes cliniques objectifs est notée avec une augmentation du TBUT de 6,98 ± 1,41s. à 9,27 ± 1,25s. (p <0,001) et une diminution de l’échelle ME-CHECK-meiboscale (p < 0,001). Une diminution du ME-CHECK-meiboscale est observée dans 90% des cas, ainsi qu’une amélioration significative des signes cliniques subjectifs au questionnaire ME-CHECK (p < 0,001). Aucun événement indésirable n’est à signaler. Le traitement « EyeLight » de 2 à 5 séances -selon la sévérité du MGD dans chaque œil- a montré une amélioration des signes cliniques objectifs, des symptômes, et semble être un traitement efficace pour le SOS lié au MGD réfractaire au traitement conventionnel.
Presented as a poster at the American Academy of Ophthalmology Annual Meeting, Dallas, November 1992.
The author has no proprietary interest in the instruments named in this study.
Supported in part by a grant from Research to Prevent Blindness, Inc, New York.