Effects of punctal occlusion on global tear proteins in patients with dry eye

Multi-System-Level Analysis with RNA-Seq on Pterygium Inflammation Discovers Association between Inflammatory Responses, Oxidative Stress, and Oxidative Phosphorylation

A pterygium is a common conjunctival degeneration and inflammatory condition. It grows onto the corneal surface or limbus, causing blurred vision and cosmetic issues. Ultraviolet is a well-known risk factor for the development of a pterygium, although its pathogenesis remains unclear, with only limited understanding of its hereditary basis. In this study, we collected RNA-seq from both pterygial tissues and conjunctival tissues (as controls) from six patients (a total of twelve biological samples) and retrieved publicly available data, including eight pterygium samples and eight controls. We investigated the intrinsic gene regulatory mechanisms closely linked to the inflammatory reactions of pterygiums and compared Asian (Korea) and the European (Germany) pterygiums using multiple analysis approaches from different perspectives. The increased expression of antioxidant genes in response to oxidative stress and DNA damage implies an association between these factors and pterygium development. Also, our comparative analysis revealed both similarities and differences between Asian and European pterygiums. The decrease in gene expressions involved in the three primary inflammatory signaling pathways-JAK/STAT, MAPK, and NF-kappa B signaling-suggests a connection between pathway dysfunction and pterygium development. We also observed relatively higher activity of autophagy and antioxidants in the Asian group, while the European group exhibited more pronounced stress responses against oxidative stress. These differences could potentially be necessitated by energy-associated pathways, specifically oxidative phosphorylation.

Applications of artificial intelligence and bioinformatics methodologies in the analysis of ocular biofluid markers: a scoping review

PURPOSE

This scoping review summarizes the applications of artificial intelligence (AI) and bioinformatics methodologies in analysis of ocular biofluid markers. The secondary objective was to explore supervised and unsupervised AI techniques and their predictive accuracies. We also evaluate the integration of bioinformatics with AI tools.

METHODS

This scoping review was conducted across five electronic databases including EMBASE, Medline, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Web of Science from inception to July 14, 2021. Studies pertaining to biofluid marker analysis using AI or bioinformatics were included.

RESULTS

A total of 10,262 articles were retrieved from all databases and 177 studies met the inclusion criteria. The most commonly studied ocular diseases were diabetic eye diseases, with 50 papers (28%), while glaucoma was explored in 25 studies (14%), age-related macular degeneration in 20 (11%), dry eye disease in 10 (6%), and uveitis in 9 (5%). Supervised learning was used in 91 papers (51%), unsupervised AI in 83 (46%), and bioinformatics in 85 (48%). Ninety-eight papers (55%) used more than one class of AI (e.g. > 1 of supervised, unsupervised, bioinformatics, or statistical techniques), while 79 (45%) used only one. Supervised learning techniques were often used to predict disease status or prognosis, and demonstrated strong accuracy. Unsupervised AI algorithms were used to bolster the accuracy of other algorithms, identify molecularly distinct subgroups, or cluster cases into distinct subgroups that are useful for prediction of the disease course. Finally, bioinformatic tools were used to translate complex biomarker profiles or findings into interpretable data.

CONCLUSION

AI analysis of biofluid markers displayed diagnostic accuracy, provided insight into mechanisms of molecular etiologies, and had the ability to provide individualized targeted therapeutic treatment for patients. Given the progression of AI towards use in both research and the clinic, ophthalmologists should be broadly aware of the commonly used algorithms and their applications. Future research may be aimed at validating algorithms and integrating them in clinical practice.

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.

Current uses of artificial intelligence in the analysis of biofluid markers involved in corneal and ocular surface diseases: a systematic review

Corneal and ocular surface diseases (OSDs) carry significant psychosocial and economic burden worldwide. We set out to review the literature on the application of artificial intelligence (AI) and bioinformatics for analysis of biofluid biomarkers in corneal and OSDs and evaluate their utility in clinical decision making. MEDLINE, EMBASE, Cochrane and Web of Science were systematically queried for articles using AI or bioinformatics methodology in corneal and OSDs and examining biofluids from inception to August 2021. In total, 10,264 articles were screened, and 23 articles consisting of 1058 individuals were included. Using various AI/bioinformatics tools, changes in certain tear film cytokines that are proinflammatory such as increased expression of apolipoprotein, haptoglobin, annexin 1, S100A8, S100A9, Glutathione S-transferase, and decreased expression of supportive tear film components such as lipocalin-1, prolactin inducible protein, lysozyme C, lactotransferrin, cystatin S, and mammaglobin-b, proline rich protein, were found to be correlated with pathogenesis and/or treatment outcomes of dry eye, keratoconus, meibomian gland dysfunction, and Sjögren's. Overall, most AI/bioinformatics tools were used to classify biofluids into diseases subgroups, distinguish between OSD, identify risk factors, or make predictions about treatment response, and/or prognosis. To conclude, AI models such as artificial neural networks, hierarchical clustering, random forest, etc., in conjunction with proteomic or metabolomic profiling using bioinformatics tools such as Gene Ontology or Kyoto Encylopedia of Genes and Genomes pathway analysis, were found to inform biomarker discovery, distinguish between OSDs, help define subgroups with OSDs and make predictions about treatment response in a clinical setting.

Superior limbic keratoconjunctivitis: Update on pathophysiology and management

Superior limbic keratoconjunctivitis (SLK) is an under-recognized condition characterized by a final common pathologic presentation of superior conjunctival and limbal inflammation and staining. Existing literature attributes both microtrauma and local inflammation, frequently in the setting of tear film insufficiency, as the underlying mechanisms that lead to a self-perpetuating pathologic process dependent in on inflammatory cells and signaling. Effective treatments act by targeting inflammation and by mitigating mechanical stressors. This critical review discusses the latest in our understanding of the pathophysiology of SLK and how it guides our treatment strategies.

Tear proteomic analysis of young glasses, orthokeratology, and soft contact lens wearers

Contact lens-related ocular surface complications occur more often in teenagers and young adults. The purpose of this study was to determine changes in tear proteome of young patients wearing glasses (GL), orthokeratology lenses (OK), and soft contact lenses (SCL). Twenty-two young subjects (10-26 years of age) who were established GL, OK, and SCL wearers were recruited. Proteomic data were collected using a data-independent acquisition-parallel accumulation serial fragmentation workflow. In total, 3406 protein groups were identified, the highest number of proteins identified in Schirmer strip tears to date. Eight protein groups showed higher abundance, and 11 protein groups showed lower abundance in the SCL group compared to the OK group. In addition, the abundance of 82 proteins significantly differed in children compared to young adult GL wearers, among which 67 proteins were higher, and 15 proteins were lower in children. These 82 proteins were involved in inflammation, immune, and glycoprotein metabolic biological processes. In summary, this work identified over 3000 proteins in Schirmer Strip tears. The results indicated that tear proteomes were altered by orthokeratology and soft contact wear and age, which warrants further larger-scale study on the ocular surface responses of teenagers and young adults separately to contact lens wear. SIGNIFICANCE: In this work, we examined the tear proteomes of young patients wearing glasses, orthokeratology lenses, and soft contact lenses using a data-independent acquisition-parallel accumulation serial fragmentation (diaPASEF) workflow and identified 3406 protein groups in Schirmer strip tears. Nineteen protein groups showed significant abundance changes between orthokeratology and soft contact lens wearers. Moreover, eighty-two protein groups significantly differed in abundance in children and young adult glasses wearers. As a pilot study, this work provides a deep coverage of tear proteome and suggests the need to investigate ocular responses to contact lens wear separately for children and young adults.

Changes of Dry Eye Parameters Especially Meibomian Gland Functions After Punctal Plugs Insertion in Aqueous-Deficient Dry Eye Patients

Background

The study aimed at investigating the changes of dry eye parameters, especially the meibomian gland function in dry eye patients with primary Sjögren's syndrome (SS) and non-Sjögren's syndrome (non-SS) before and after punctal plugs insertion.

Material and Methods

The SS and non-SS dry eye patients that received punctal plugs insertion were prospectively investigated. This study recruited fifty patients. The standardized patient evaluation of eye dryness (SPEED), ocular surface disease index (OSDI), tear meniscus height (TMH), non-invasive Keratographic breakup time (NIKBUT), Schirmer test without anesthesia (Schirmer I Test, SI T), corneal fluorescein staining (CFS), the meibomian gland dropout (meiboscore), meibum expressibility score (MES), meibum quality score (MQS), lid margin abnormalities and the lipid layer thickness (LLT) were analyzed at pre-obstruction, 2 weeks, 2 months and 6 months following the obstruction.

Results

Our study observed a statistically significant improvement in ocular symptom scores (SPEED and OSDI scores) after punctal plugs insertion at every visit in both SS and non-SS patients (all p < 0.05). A similar pattern was observed in TMH, SI T, NIKBUT and CFS score in both groups (all p < 0.05), except that NIKBUT and CFS score had no obvious change in SS group at 6 months (P > 0.05). In terms of the meibomian gland evaluation, meiboscore did not change significantly, MES decreased at 2 and 6 months and MQS decreased only at 2 months in both groups. The lid margin abnormalities of the non-SS group were significantly improved at 2 and 6 months, while that of the SS group had changes only at 2 months. Interestingly, LLT in non-SS group continued to rise, reaching a higher level at 2 months (p < 0.05), while LLT in SS group increased only at 2 months (p < 0.05). Meanwhile, after the puntcal plugs insertion, non-SS group showed better outcomes concerning some parameters, such as lower ocular symptom scores, higher TMH and significantly greater LLT, compared with that in SS group (all p < 0.05).

Conclusions

Our study revealed that dry eye symptoms and signs, including meibomian gland function, improved for at least 6 months in non-SS dry eye patients as well as in SS dry eye patients after punctal plugs insertion.

Dry eye disease and proteomics

Dry eye disease (DED) is a highly prevalent disease worldwide mostly associated with age, though other factors such as screen use and contact lens wear explain why it is increasingly diagnosed in younger people. DED also disproportionately affects women. Symptoms include eye dryness, burning, pain and sensitivity to light that can significantly affect quality of life. This condition may progress to cause lasting damage to the ocular surface if left untreated. Currently, diagnosis is through assessment of signs and symptoms determined by clinical tests and questionnaires. However, there is considerable overlap between normal and DED result distributions of currently available metrics as signs and symptoms fluctuate over time and with disease severity. Importantly, the non-targeted approach of proteomics means that significant changes in novel proteins may be discovered. Proteomics is a powerful tool that has been applied to the field of DED to understand changes at a biochemical level, uncover new disease biomarkers and determine the success of clinical interventions. While individual proteins may not be sensitive enough when used as single biomarkers, proteomics opens the possibility to uncover several relevant proteins that may be combined in a panel to provide more accurate diagnostic value i.e. parallel testing. In this review we discuss the use of proteomics in DED research and the potential for application of proteomic results in the clinic. We also identify shortcomings and future avenues for research.

Assessment and Management of Dry Eye Disease and Meibomian Gland Dysfunction: Providing a Singapore Framework

ABSTRACT

The purpose of this article is to provide a framework for general ophthalmologists in Singapore to manage dry eye. This framework considers the evidence in the literature as well as recommendations from expert panels such as the Tear Film & Ocular Surface Society Dry Eye Workshop II and the Asia Cornea Society Workgroup.This article covers the assessment of patient medical history and ask triage questions to identify local and systemic causes of dry eye disease (DED), excluding other possible causes, as well as the risk factors for DED and ocular surface inflammation. Evaluation of clinical signs to establish the diagnosis of DED and differentiation from other causes of irritable, red eyes are described. Tests for understanding the underlying disease processes and severity of DED are also presented.Management of dry eye should involve patient education and engagement. Information about the natural history and chronic nature of DED should be provided to improve long-term management of the disease and enhance compliance. Aggravating factors should be removed or lessened.We provide a guide to determine the most appropriate treatment (or combination of treatments) based on the severity and cause(s) of the disease, as well as the patient's needs and preferences. The aim of the management is to relieve ocular discomfort and prevent worsening of symptoms and signs, as well as to optimize visual function and minimize structural ocular damage. We also discuss the systematic follow-up and assessment of treatment response, as well as monitoring side effects of treatment, bearing in mind continuous support and reassurance to patients.

Looking deeper into ocular surface health: an introduction to clinical tear proteomics analysis

Ocular surface diseases are becoming more prevalent worldwide. Reasons for this include the ongoing population ageing and increasing use of digital displays, although ophthalmologists have a wide selection of tools, which can be implemented in the evaluation of the ocular surface health, methods, which enable the in-depth study of biological functions are gaining more interest. These new approaches are needed, since the individual responses to ocular surface diseases and treatments can vary from person to person, and the correlations between clinical signs and symptoms are often low. Modern mass spectrometry (MS) methods can produce information on hundreds of tear proteins, which in turn can provide valuable information on the biological effects occurring on the ocular surface. In this review article, we will provide an overview of the different aspects, which are part of a successful tear proteomics study design and equip readers with a better understanding of the methods most suited for their MS-based tear proteomics study in the field of ophthalmology and ocular surface.

Review of Approaches for Increasing Ophthalmic Bioavailability for Eye Drop Formulations

Ophthalmic diseases represent a significant problem as over 2 billion people worldwide suffer from vison impairment and blindness. Eye drops account for around 90% of ophthalmic medications but are limited in success due to poor patient compliance and low bioavailability. Low bioavailability can be attributed to short retention times in the eye caused by rapid tear turnover and the difficulty of drug diffusion through the multi-layered structure of the eye that includes lipid-rich endothelial and epithelial layers as well as the stroma which is high in water content. In addition, there are barriers such as tight junctional complexes in the corneal epithelium, lacrimal turnover, nasolacrimal drainage, blinking reflexes, efflux transporters, drug metabolism by ocular enzymes, and drug binding to or repulsion from conjunctival mucins, tear proteins, and melanin. In order to maximize transport through the cornea while minimizing drug loss through other pathways, researchers have developed numerous methods to improve eye drop formulations including the addition of viscosity enhancers, permeability enhancers, mucoadhesives, and vasoconstrictors, or using formulations that include puncta occlusion, nanocarriers, or prodrugs. This review explains the mechanism behind each of these methods, examines their history, analyzes previous and current research, evaluates future applications, and discusses the pros and cons of each technique.

Efficacy of omega-3 fatty acids and punctal plugs in the prevention of isotretinoin-associated ocular surface disease

PURPOSE

To investigate the effects of omega-3 fatty acids and punctal plugs on tear film and ocular surface parameters in patients receiving systemic isotretinoin therapy.

METHODS

This is a prospective randomized study that included 180 eyes of 90 patients who had systemic isotretinoin therapy (120-150 mg/kg for at least 4-6 months). Exclusion criteria: DED according to the diagnostic criteria of TFOS DEWS II. Patients were assigned into three groups; (1) O3FAs/PPs group: A soft preloaded silicone plug was inserted in the inferior punctum of both eyes and received oral O3FAs two capsules twice daily total daily dose of 1040 mg/day for 6 months. (2) PPs group: A soft preloaded silicone plug was inserted in the inferior punctum of both eyes and received oral placebo. (3) Isotretinoin group: No intervention was done. At baseline, 1 week, 1, 3, and 6 months of study, Ocular surface evaluation tests were done in following order: OSDI, tear osmolarity, Schirmer's I test, TBUT, ocular surface staining score, and meibomian gland expression.

PRIMARY OUTCOME MEASURES

The changes in measurement of ocular surface evaluation tests including ocular surface disease index (OSDI), tear film breakup time (TFBUT), corneal staining, tear osmolarity, and meibomian gland expression at 6 months.

RESULTS

There are significant changes between all groups at 6 months follow-up. The ocular surface parameters were better for the PPs and O3FAs/PPs groups than the isotretinoin group. The isotretinoin group showed worsening of ocular surface parameters including a significant decrease of FTBUT and an increase of OSDI score, corneal staining score, tear osmolarity, and meibomian expression score. There was no significant difference in ST1 throughout the whole study in all groups. At 6 months follow-up, there were no statistically significant differences between PPs and O3FAs/PPs groups except meibomian expression score which showed a significant increase in PPs group.

CONCLUSION

Our cohort highlights the beneficial effects of the combination of O3FAs supplementation with PPs in the prevention of isotretinoin-associated OSD in this sample study.

Tear Film Proteomics Reveal Important Differences Between Patients With and Without Ocular GvHD After Allogeneic Hematopoietic Cell Transplantation

Purpose

To date, no biomarkers for ocular graft versus host disease (GvHD), a frequent complication following allogeneic hematopoietic cell transplantation (HCT), exist. In this prospective study, we evaluated the potential of human tear proteins as biomarkers for ocular GvHD.

Methods

Tears from 10 patients with moderate-to-severe ocular GvHD were compared to 10 patients without ocular GvHD. After a full ocular surface clinical examination, tears were collected onto Schirmer strips and protein composition was analyzed by liquid chromatography tandem mass spectrometry. Statistical evaluation was performed using the Mann-Whitney U test to compare means and the false discovery rate method to adjust for multiple comparisons. Functional annotation of differentially expressed proteins was done with the PANTHER classification system.

Results

We identified 282 proteins in tryptic digests of Schirmer strips; 79 proteins were significantly differentially expressed between the two groups, from which 54 were up- and 25 downregulated. The most upregulated proteins were classified as nucleic acid binding and cytoskeletal proteins, while the most extensively downregulated proteins belong to an array of classes including transfer and receptor proteins, enzyme modulators, and hydrolases. In addition to proteins already confirmed as differentially expressed in dry eye disease, we report changes in 36 novel proteins.

Conclusions

This study reports the proteomic profile of tears in ocular GvHD for the first time and identifies a number of unique differentially expressed proteins. Further studies with a higher number of participants are necessary to confirm these results and to evaluate the reliability of these expression patterns in longitudinal studies.

[Punctal and canalicular plugs: Indications, efficacy and safety (French translation of the article)]

Lacrimal occlusion with punctal or canalicular plugs have been used to treat dry eye disease for more than 40 years. Indeed, punctal plugs constitute a safe and effective tool to retain the natural tear film and prolong the effect of tear substitutes. A wide variety of plugs is available, differing in their design, location (punctal versus canalicular) and their resorbability. There indications have increasingly broadened, and they are now one of the treatment options for numerous ocular surface diseases. Current research focuses on using punctal plugs for extended delivery of drugs to the ocular surface. This review addresses physiology of lacrimal drainage, available models of punctal plugs, their indications, practical details of prescribing and placing punctal and canalicular plugs, and possible complications.

Punctal and canalicular plugs: Indications, efficacy and safety

Lacrimal occlusion with punctal or canalicular plugs have been used to treat dry eye disease for more than 40 years. Indeed, punctal plugs constitute a safe and effective tool to retain the natural tear film and prolong the effect of tear substitutes. A wide variety of plugs is available, differing in their design, location (punctal versus canalicular) and their resorbability. There indications have increasingly broadened, and they are now one of the treatment options for numerous ocular surface diseases. Current research focuses on using punctal plugs for extended delivery of drugs to the ocular surface. This review addresses physiology of lacrimal drainage, available models of punctal plugs, their indications, practical details of prescribing and placing punctal and canalicular plugs, and possible complications.

Tear protein analysis in presumed congenital alacrima

Objectives

It is often hard to reach a definitive diagnosis of congenital alacrima because of the difficultly in proving the lack of lacrimal tissue. We report here the distinct tear protein profile in presumed congenital alacrima.

Patients and methods

A 13-year-old girl with presumed congenital alacrima and 15 healthy volunteers aged 23–35 years were included in this study. Tears were collected using Schirmer strips, and tear protein analyses were performed. Tear samples were collected from the patient with alacrima before and after surgical punctal occlusion of both the upper and lower puncta, and tear protein extract was fractionated using HPLC. Lactoferrin and albumin concentrations in the tears were separately determined using ELISA.

Results

The chromatogram in the patient greatly differed from that in normal subjects with low concentrations of secretory IgA, lipocalin-1, and lysozyme. ELISA results indicated that the tear fluid in the patient contained a high concentration of albumin but a minimal concentration of lactoferrin. Punctal occlusion improved the ocular surface findings, but major lacrimal protein concentrations remained low and tear albumin concentrations further increased.

Conclusion

The tear protein profile of a patient with presumed congenital alacrima greatly differed from that of normal subjects. Tear protein analysis may be useful in making a diagnosis of congenital alacrima and in assessing the efficacy and mechanism of punctal occlusion.

Five Misconceptions Related to Punctal Plugs in Dry Eye Management

Punctal plugs are an effective treatment option for patients with aqueous-deficient dry eye refractory to topical medications. However, punctal plugs are not commonly used in clinical practice mainly because of various misconceptions, rather than clinical complications. We analyzed previous studies and present 5 misconceptions related to punctal plugs. The first and most important misconception is that ocular surface inflammation should be sufficiently controlled before punctal plug insertion. However, it is unclear how ocular surface inflammation can be sufficiently controlled in patients refractory to conventional topical medications. The second misconception is that silicone punctal plugs are made of nonabsorbable materials and, therefore, permanent. In fact, silicone plugs are reversible and can be easily removed if necessary. Therefore, depending on the specific type, nonabsorbable plugs may be classified as reversible or permanent. The third misconception is that punctal plugs disrupt normal tear drainage. However, punctal plugs maintain natural tears on the ocular surface for extended periods and reduce the frequency of artificial tear use. The fourth is that all punctal and canalicular plugs have similar effects. The efficacy and complication rates differ depending on plug types. The fifth misconception about punctal plugs is that they are effective only in aqueous-deficient dry eye disease. Many studies have reported that plugs are effective in a variety of ocular diseases and conditions. Understanding these 5 misconceptions may provide an opportunity to rethink the use of silicone punctal plugs in clinical practice.