Clinical and biochemical analysis of the ageing tear film

Effectiveness and safety of Jiejing Runmu decoction in treatment of dry eye disease

OBJECTIVE

To investigate the effectiveness and safety of Jiejing Runmu decoction in relieving the clinical manifestations of dry eye disease (DED).

DESIGN AND INTERVENTIONS

This single-arm prospective intervention study was conducted at the Peking University Third Hospital and People's Hospital of Yongqing. Of the 211 patients recruited, 200 completing the follow-up were included in the analysis. Patients received Jiejing Runmu decoction once a day for 4 weeks continuously, without any change in eye care habits. Individuals were evaluated at four time points: pretreatment (baseline), 2 weeks, 1 month, and 3 months (2 months after completion of treatment), using the Ocular Surface Disease Index (OSDI), tear film breakup time (TBUT), corneal fluorescein staining, Schirmer test I and meibomian gland assessments. Adverse effects were evaluated at each follow-up visit and systematic examinations were performed during the first and last visits.

RESULTS

OSDI, TBUT, corneal fluorescein staining, Schirmer test I, meibomian gland expressibility, and quality of secretions improved at 2 weeks, 1 month and 3 months compared to baseline (P < 0.0001). No significant differences were found between the sexes. Patients above 45 years showed worse subjective symptoms and objective signs, and greater improvements in corneal fluorescein staining, meibomian gland expressibility, and quality of secretions were observed in this group. No obvious adverse effects were detected during any follow-up visit.

CONCLUSION

Jiejing Runmu decoction significantly improved both the subjective symptoms and objective signs of DED, with favorable tolerance.

2022 Glenn A. Fry Award lecture: Enhancing clinical assessment for improved ophthalmic management

ABSTRACT

Detailed clinical assessment is critical to allow sensitive evaluation of the eye and its management. As technology advances, these assessment techniques can be adapted and refined to improve the detection of pathological changes of ocular tissue and their impact on visual function. Enhancements in optical medical devices including spectacle, contact, and intraocular lenses have allowed for a better understanding of the mechanism and amelioration of presbyopia and myopia control. Advancements in imaging technology have enabled improved quantification of the tear film and ocular surface, informing diagnosis and treatment strategies. Miniaturized electronics, large processing power, and in-built sensors in smartphones and tablets capacitate more portable assessment tools for clinicians, facilitate self-monitoring and treatment compliance, and aid communication with patients. This article gives an overview of how technology has been used in many areas of eye care to improve assessments and treatment and provides a snapshot of some of my studies validating and using technology to inform better evidence-based patient management.

Human Tear Protein Analysis Using a Quantitative Microfluidic System: A Pilot Study

OBJECTIVES

Human tears have the potential to be used as biomarkers to aid in the diagnosis and management of dry eye disease (DED). This prospective, controlled pilot study aimed to investigate the hypothesis that a panel of tear protein profiles can be detected and are repeatable when analyzed using a miniaturized quantitative microfluidic system.

METHODS

Ten participants were recruited following institutional ethics committee approval. Participants attended two visits 1 week apart when the following measurements were taken in a sequence: tear meniscus height, noninvasive breakup time, ocular redness, tear collection, and corneal and conjunctival staining. Basal tears (>4 µL) were collected using glass microcapillary tubes. Tears were processed to analyze a panel of proteins (14-230 kDa) following the manufacturer's guidelines using a miniaturized quantitative microfluidic system (Protein 230 LabChip with Agilent 2100 Bioanalyzer). Demographics of the clinical measurements and a comparison of the panel of identified proteins and their repeatability were made.

RESULTS

Mean age of the participants was 20.8±1.6 years, nine were females, three fulfilled the TFOS DEWS-II diagnostic criteria for DED. The total protein concentration across participants was 6.72±3.56 mg/mL. Several proteins (lysozyme C, lipocalin 1, IgA light chain, zinc-α2-glycoprotein, albumin, and lactoferrin) were identified at both visits for seven or more participants. There were no significant differences ( P >0.05) in individual protein concentrations between the two visits. A high correlation was found between the two visits for all proteins where correlation coefficient ranged between 0.63 and 0.98 ( P <0.05).

CONCLUSION

The protein profiles measured by the quantitative microfluidic system are repeatable, thus validating quantitative microfluidic system as a reliable method for investigating a panel of tear proteins. This method is quick, affordable, requires only 4 μL of tear, and is relatively easy method to perform that can be incorporated in a clinical setting. Further studies in larger clinical setting may be beneficial exploring the usability of this method in various patient groups.

Mechanisms of Extraorbital Lacrimal Gland Aging in Mice: An Integrative Analysis of the Temporal Transcriptome

Purpose

This study used high-throughput RNA sequencing (RNA-Seq) and bioinformatics analysis to investigate the altered transcriptome profile of aging lacrimal glands in mice that occurs over the course of a 24-hour cycle.

Methods

Male C57BL/6J mice aged 12 weeks (young) and 20 months (aging) were housed in a pathogen-free setting with a 12-hour light/12-hour dark cycle. Throughout a 24-hour cycle, mouse extraorbital lacrimal glands (ELGs) were collected at eight time points at three-hour intervals. To prepare for the high-throughput RNA-Seq, whole mRNA was extracted. Differentially expressed genes (DEGs) in the young and aging groups were subjected to bioinformatic analysis based on diurnal patterns. Furthermore, the cell populations in which significant DEGs express and signaling pathways occur were validated at the single-cell RNA sequencing (scRNA-seq) level.

Results

The total transcriptome composition was significantly altered in aging ELGs compared with that in young mouse ELGs at eight time points during the 24-hour cycle, with 864 upregulated and 228 downregulated DEGs, which were primarily enriched in inflammatory pathways. Further comparative analysis of the point-to-point transcriptome revealed that aging ELGs underwent alterations in the temporal transcriptome profile in several pathways, including the inflammation-related, metabolism-related, mitochondrial bioenergetic function-associated, synaptome neural activity-associated, cell processes-associated, DNA processing-associated and fibrosis-associated pathways. Most of these pathways occurred separately in distinct cell populations.

Conclusions

Transcriptome profiles of aging lacrimal glands undergo considerable diurnal time-dependent changes; this finding offers a comprehensive source of information to better understand the pathophysiology of lacrimal gland aging and its underlying mechanisms.

Viscoelastic properties of the human tear film

When considering eye blinking from a tribological perspective, tear viscosity is expected to play a fundamental role. The application of rheological techniques to describe the tear film dates back to the late 1980s, but there has been a continuous need of reappraisal due to new findings in tear film biochemistry and to the development of new methods of physico-chemical characterization. This review provides an overview on tear rheological behavior by analyzing the peer-reviewed literature on this topic. Specifically, examples of in-vitro and in-vivo viscosity measurements are detailed, highlighting experimental criticalities and the need of a standard convention for rheological techniques to compare data across different studies, of analyses on tears of single individuals even within the limits of the low volume available, and of a further development of in-vivo techniques. Then, the controversial role of specific tear components on viscosity is discussed, together with the alterations associated to dry eye disease and contact lens wear. Finally, an updated focus is reported on the viscosity of artificial tears formulations.

A Review of Emerging Tear Proteomics Research on the Ocular Surface in Ocular Allergy

Ocular allergy is an immunoglobulin E-mediated Type I hypersensitivity reaction localised to the ocular surface and surrounding tissues. Primary signs and symptoms of ocular allergy include itching, redness, irritation and inflammation. Eye-rubbing caused by itching has been shown to alter ocular surface protein concentrations in conditions linked to ocular allergy such as keratoconus. In keratoconus, the cornea begins to thin and sag over time, leading to progressive vision loss and blindness in severe conditions. Due to the high incidence of ocular allergy sufferers rubbing their eyes in response to symptoms of itching, the protein landscape of the ocular surface may be significantly altered. Differential protein expression caused by long-term inflammation and eye-rubbing may lead to subsequent changes in ocular surface structure and function over time. This review aims to summarise and explore the findings of current ocular allergy proteome research conducted using techniques such as gel electrophoresis, mass spectrometry and lab-on-a-chip proteomics. Proteins of interest for this review include differentially expressed immunoglobulins, mucins, functional proteins, enzymes and proteins with previously uncharacterised roles in ocular allergy. Additionally, potential applications of this research are addressed in terms of diagnostics, drug development and future research prospects.

Vision through Healthy Aging Eyes

As life expectancy grows, so too will the number of people adversely affected by age. Although it is acknowledged that many conditions and diseases are associated with age, this mini-review will present a current update of the various visual changes that generally occur in healthy individuals disregarding the possible effects of illness. These alterations influence how the world is perceived and in turn can affect efficiency or the ability to perform ordinary daily tasks such as driving or reading. The most common physical developments include a decreased pupil size and retinal luminance as well as changes both in intercellular and intracellular connections within the retina along the pathway to the visual cortex and within the visual cortex. The quantity and the physical location of retinal cells including photoreceptors, ganglion and bipolar retinal cells are modified. The clarity of intraocular organs, such as the intraocular lens, decreases. These all result in common visual manifestations that include reduced visual acuity, dry eyes, motility changes, a contraction of the visual field, presbyopia, reduced contrast sensitivity, slow dark adaptation, recovery from glare, variation in color vision and a decreased visual processing speed. Highlighting these prevalent issues as well as current and possible future innovations will assist providers to formulate treatments and thereby conserve maximum independence and mobility in the modern mature population.

Longitudinal Tear Protein Changes Correlate with Ocular Chronic GVHD Development in Allogeneic Hematopoietic Stem Cell Transplant Patients

Ocular graft-versus-host disease (oGVHD) is a manifestation of chronic GVHD, frequently occurring in patients after allogeneic hematopoietic stem cell transplant (HSCT). We analyzed tear protein changes before and after allogeneic HSCT, and correlated their levels with the oGVHD development. This retrospective study included 102 patients, and data were recorded before the conditioning treatment, and after 3 to 6 months postoperatively. Tear protein analysis was performed with the Agilent-2100 Bioanalyzer on individual tears sampled by aspiration. Total protein (TP), Lysozyme-C (LYS-C), Lactoferrin (LACTO), Lipocalin-1 (LIPOC-1), Transferrin (TRANSF), Albumin (ALB), and Zinc-alpha-2-glycoprotein (ZAG-2) levels were retrieved and statistically analyzed. Following HSCT forty-three patients developed oGVHD. TP, LACTO, LYS-C, and ZAG-2 levels significantly decreased post-HSCT as compared to pre HSCT levels. In univariate analysis, TP, LACTO, and ZAG-2 decrease was associated with an increased development of oGVHD (OR = 4.49; 95% CI, 1.9 to 10.5; p < 0.001; OR = 3.08; 95% CI 1.3 to 7.6; p = 0.01; OR = 11.1; 95% CI 2.7 to 46.6; p < 0.001, respectively). TRANSF post-HSCT levels significantly increased (OR 15.7; 95% CI, 4.1 to 52.2; p = 0.0001). No pre-post-HSCT changes were shown in ALB and LIPOC-1 levels. Data suggest that TP content, LACTO, TRANSF, and ZAG-2 pre-post changes might be significant predictors of oGVHD development.

Cytokine and Chemokine Concentration in the Tear of Patients with Age-Related Cataract

PURPOSE

The present study measured 41 soluble mediators in the tear of 19 patients with age-related cataract and 32 healthy adults as controls.

MATERIALS AND METHODS

This was a prospective, case-control study in which, using multiple immunoassays, we measured in tear samples the following molecules: EGF, FGF-2, Eotaxin, TGF-α, G-CSF, Flt-3L, GM-CSF, Fractalkine, IFN-α2, IFN-γ, GRO, IL-10, MCP-3, IL-12p40, MDC, IL-12p70, PDGF-AA, IL-13, PDGF-AB/BB, IL-15, sCD40L, IL-17a, IL-1ra, IL-1α, IL-9, IL-1β, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IP-10, MCP-1, MIP-1α, MIP-1β, RANTES, TNFα, TNFβ, VEGF. Statistical analyses were done by multiple adjusted models and p values were corrected by the Benjamini and Hochberg method.

RESULTS

We did not find significant differences in the amount of the tested molecules in the tear fluid between cataract patients and controls. Correlation analyses relative to age were carried out for both groups. Analysis of MCP-1 tear levels revealed a direct correlation with age for normal healthy controls as well as for cataract patients. But IL-6 tear levels correlated with age only in the group of cataract patients. In addition, IL1-ra tear levels correlated with cataract nuclear grade; higher grades were associated with higher IL-1ra concentrations.

CONCLUSIONS

Our results suggest that ocular aging is accompanied by increased production of IL-6 and MCP-1, which can be measured in tear fluid.

ABBREVIATIONS

AMD: Age-Related Macular Degeneration; EGF: Epidermal growth factor; Eotaxin: Eosinophil chemotactic proteins; FasL: Fas ligand; FGF-2: Basic fibroblast growth factor 2; Flt-3L: Fms related tyrosine kinase 3 ligand; G-CSF: Granulocyte colony stimulating factor; GM-CSF: Granulocyte macrophage colony stimulating factor; GRO: Growth regulated protein; HGF: Human growth factor; ICAM-1: Intercellular adhesion molecule-1; IFNα2: Interferon alpha 2; IFNγ: Interferon gamma; IL: Interleukin; IL-1ra: Interleukin-1 receptor antagonist; IL-12p40: Interleukin-12 subunit p40; IL-12p70: Interleukin-12 subunit p70; IP-10: Interferon gamma-induced protein 10; MCP-1: Monocyte chemotactic protein 1; MCP-3: Monocyte chemotactic protein 3; MDC: Macrophage derived chemokine; MIG: Monokine induced by gamma interferon; MIP-1α: Macrophage inflammatory proteins 1 alpha; MIP-1β: Macrophage inflammatory proteins 1 beta; MMPs: Matrix metalloproteinases; MMP-9: Matrix metalloproteinase 9; PAI1: Plasminogen activator inhibitor 1; PDGF-AA: Platelet-derived growth factor subunit AA; PDGF-AB/BB: Platelet-derived growth factor subunit AB and BB; PIGF: Placenta growth factor; RANTES: Regulated on activation, normal T cell expressed and secreted; SAA: Serum amyloid A; sCD40L: Soluble CD40 ligand; sTNF-RII: Soluble tumor necrosis factor receptor; TBUT Tear breakup time; TGF-α: Transforming growth factor alpha; TGF-β: Transforming growth factor beta; TNFα: Tumor necrosis factor alpha; TNFβ: Tumor necrosis factor beta; VCAM: Vascular cell adhesion molecule; VEGF: Vascular endothelium growth factor.