Tear biomarkers

An extensive exploration of lacrimal fluid molecular biomarkers in understanding and diagnosing a spectrum of ocular and systemic diseases is presented. The chapter provides an overview of lacrimal fluid composition, elucidating the roles of proteins, lipids, metabolites, and nucleic acids within the tear film. Pooled versus single-tear analysis is discussed to underline the benefits and challenges associated with both approaches, offering insights into optimal strategies for tear sample analysis. Subsequently, an in-depth analysis of tear collection methods is presented, with a focus on Schirmer's test strips and microcapillary tubes methods. Alternative tear collection techniques are also explored, shedding light on their applicability and advantages. Variability factors, including age, sex, and diurnal fluctuations, are examined in the context of their impact on tear biomarker analysis. The main body of the chapter is dedicated to discussing specific biomarkers associated with ocular discomfort and a wide array of ocular diseases. From dry eye disease and thyroid-associated ophthalmopathy to keratoconus, age-related macular degeneration, diabetic retinopathy, and glaucoma, the intricate relationship between molecular biomarkers and these conditions is thoroughly dissected. Expanding beyond ocular pathologies, the chapter explores the applicability of tear biomarkers in diagnosing systemic diseases such as multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer's disease, Parkinson's disease, and cancer. This broader perspective underscores the potential of lacrimal fluid analysis in offering non-invasive diagnostic tools for conditions with far-reaching implications.

The role of regulated necrosis in inflammation and ocular surface diseases

In recent decades, numerous types of regulated cell death have been identified, including pyroptosis, ferroptosis and necroptosis. Regulated necrosis is characterized by a series of amplified inflammatory responses that result in cell death. Therefore, it has been suggested to play an essential role in the pathogenesis of ocular surface diseases. The cell morphological features and molecular mechanisms of regulated necrosis are discussed in this review. Furthermore, it summarizes the role of ocular surface diseases, such as dry eye, keratitis, and cornea alkali burn, as potential disease prevention and treatment targets.

Effect of Implementation of an Eyecare Bundle on Incidence of Exposure Keratopathy in Intensive Care Unit of Tertiary Care Center in North India

Background

Lack of eyecare protective measures especially in unconscious and sedated critically ill patients, make them prone to ocular surface diseases (OSDs), e.g., exposure keratopathy. This study is aimed to frame an algorithm-based approach to eyecare via eyecare bundle to bring down the burden of OSDs in critically ill patients especially in resource-limited settings.

Materials and methods

After clearance from institutional ethical committee, a quasi-experimental single center study was conducted over a period of 6 months. Incidence of exposure keratopathy was calculated before and after induction of eyecare bundle and was compared. Statistical analysis was done using SPSS software v20. p-value of less than 0.05 was considered significant.

Results

A total of 218 patients were enrolled in the study after obtaining informed written consent and after fulfilling inclusion criteria. Patients were divided into control and experimental groups, with baseline characteristics similar in both the groups, respectively, in terms of gender, age (40 years), APACHE II score, and specialty distribution except predominantly medical patients in experimental group. In control group (n = 99), total 69 patients (41 medical and 28 surgical) developed exposure keratopathy, while in experimental group (n = 109) only 15 patients (6 medical and 9 surgical) developed exposure keratopathy, hence a significant reduction was observed. Further follow-up of patients in the experimental group was also done on Days 5 and 7, respectively.

Conclusion

The proposed protocolized algorithm-based eyecare bundle significantly reduced the incidence of exposure keratopathy in sedated, mechanically ventilated, and vulnerable critically ill patients.

How to cite this article

Sama S, Abrol R, Dhasmana R, Sharma N, Khandhuri S, Chauhan R, et al. Effect of Implementation of an Eyecare Bundle on Incidence of Exposure Keratopathy in Intensive Care Unit of Tertiary Care Center in North India. Indian J Crit Care Med 2023;27(6):426-432.

Development of a new plasma rich in growth factors membrane with improved optical properties

PURPOSE

The aim of the present work was to develop a fibrin membrane using plasma rich in growth factors (PRGF) technology with improved optical properties to be used for the treatment of ocular surface diseases.

BASIC PROCEDURES

Blood was drawn from three healthy donors, and the volume of PRGF obtained from each donor was divided into two main groups: i) PRGF or ii) platelet-poor plasma (PPP). Each membrane was then used pure or diluted to 90 %, 80 %, 70 %, 60 % and 50 %. The transparency of each of the different membranes was evaluated. The degradation and morphological characterization of each membrane was also performed. Finally, a stability study of the different fibrin membranes was performed.

MAIN FINDINGS

The transmittance test showed that the fibrin membrane with the best optical characteristics was obtained after removal of platelets and dilution of fibrin to 50 % (50 % PPP). No significant differences (p > 0.05) were observed between the different membranes in the fibrin degradation test. The stability test showed that the membrane at 50 % PPP retains its optical and physical characteristics after storage at - 20 °C for 1 month compared to storage at 4 °C.

PRINCIPAL CONCLUSIONS

The present study describes the development and characterization of a new fibrin membrane with improved optical characteristics while maintaining mechanical and biological characteristics. The physical and mechanical properties of the newly developed membrane are preserved after storage for at least 1 month at - 20 °C.

Indoor air pollution and human ocular diseases: Associated contaminants and underlying pathological mechanisms

People spend a long time indoors, especially young children. The risk of indoor pollution on human health is one of the current hotspots in environmental and public health. The human ocular surface is highly susceptible to indoor environment quality. Epidemiological data have linked human ophthalmological disorders with exposure to indoor pollution. In this review, we summarized the adverse impacts of indoor pollution on the human ocular surface. Several studies demonstrated that indoor contaminants including particulate matter, volatile/semi-volatile organic compounds, heavy metals, and fuel combustion and cigarette smoke exposure were associated with the incidence of human dry eye, conjunctivitis, glaucoma, cataracts, age-related macular degeneration, and keratitis. In addition, toxicological investigations revealed that indoor pollution-induced induced chronic inflammation, oxidative damage, and disruption of tight junctions are the main underlying pathological mechanisms for ocular surface diseases. Taken together, this review may expand the understanding of pollution-induced eye disorder and highlight the importance of reducing associated contaminants to decrease their detrimental effects on human eyes.

Particulate matter 2.5 exposure induces epithelial-mesenchymal transition via PI3K/AKT/mTOR pathway in human retinal pigment epithelial ARPE-19 cells

Exposure to particulate matter 2.5 (PM2.5) has been linked to ocular surface diseases, yet knowledge of the molecular mechanism impacted on retina pathogenesis is limited. Therefore, the purpose of this study was to explore the effects and involved factors of PM2.5 exposure in human retinal pigment epithelial APRE-19 cells. Our data revealed a decreased cell viability and an increased migratory ability in APRE-19 cells after PM2.5 stimulation. The MMP-2 and MMP-9 protein levels were markedly increased while the MMPs regulators TIMP-1 and TIMP-2 were significantly reduced in PM2.5-exposed APRE-19 cells. PM2.5 also increased pro-MMP-2 expression in the cell culture supernatants. Additionally, PM2.5 promoted the EMT markers through the activation of PI3K/AKT/mTOR pathway. Moreover, the ICAM-1 production was also remarkably increased by PM2.5 but reduced by PI3K/AKT inhibitor LY294002 in APRE-19 cells. Taken together, these results suggest that PM2.5 promotes EMT in a PI3K/AKT/mTOR-dependent manner in the retinal pigment epithelium.

Exosomes and autophagy in ocular surface and retinal diseases: new insights into pathophysiology and treatment

BACKGROUND

Ocular surface and retinal diseases are widespread problems that cannot be ignored in today's society. However, existing prevention and treatment still have many shortcomings and limitations, and fail to effectively hinder the occurrence and development of them.

MAIN BODY

The purpose of this review is to give a detailed description of the potential mechanism of exosomes and autophagy. The eukaryotic endomembrane system refers to a range of membrane-bound organelles in the cytoplasm that are interconnected structurally and functionally, which regionalize and functionalize the cytoplasm to meet the needs of cells under different conditions. Exosomal biogenesis and autophagy are two important components of this system and are connected by lysosomal pathways. Exosomes are extracellular vesicles that contain multiple signaling molecules produced by multivesicular bodies derived from endosomes. Autophagy includes lysosome-dependent degradation and recycling pathways of cells or organelles. Recent studies have revealed that there is a common molecular mechanism between exosomes and autophagy, which have been, respectively, confirmed to involve in ocular surface and retinal diseases.

CONCLUSION

The relationship between exosomes and autophagy and is mostly focused on fundus diseases, while a deeper understanding of them will provide new directions for the pathological mechanism, diagnosis, and treatment of ocular surface and retinal diseases.

Expression profiles of long noncoding RNAs in human corneal epithelial cells exposed to fine particulate matter

PURPOSE

The aim of this study was to investigate the expression profiles of long noncoding RNAs (lncRNAs) in human corneal epithelial cells (HCECs) exposed to fine particulate matter (PM_2.5) and to identify potential biological pathways involved in PM_2.5-induced toxicity in HCECs.

METHODS

Using RNA sequencing (RNA-seq) and hierarchy clustering analysis, lncRNA expression profiles in PM_2.5-treated and untreated HCECs were examined. Gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed to predict the role of altered lncRNAs in biological processes and pathways. A quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) assay was conducted to verify the RNA-seq results in HCECs and human corneal epithelial cell sheets.

RESULTS

In total, 65 lncRNAs were altered in the PM_2.5-treated HCECs, including 41 upregulated and 24 downregulated lncRNAs. The results of the qRT-PCR assay were consistent with those of the RNA-seq analysis. The expression of two significantly upregulated lncRNAs was confirmed in human corneal epithelial cell sheets. The GO analysis demonstrated that altered lncRNAs in the PM_2.5-treated HCECs were significantly enriched in three domains: cellular component, molecular function, and biological process. The KEGG pathway analysis revealed enriched pathways of lncRNA co-expressed mRNAs, including cancer, RNA transport, and Rap1 signaling.

CONCLUSIONS

Our results suggest that lncRNAs are involved in the pathogenesis of PM_2.5-induced ocular diseases, exerting their effects through biological processes and pathogenic pathways. Among the altered lncRNAs, RP3-406P24.3 and RP11-285E9.5 may play significant roles in PM_2.5-induced ocular surface injury.

Research advances in pathogenic mechanisms underlying air pollution-induced ocular surface diseases

Background

The harmful effect of aerial fine particulate matter（PM2.5）has been a serious public health issue and has attracted worldwide attention, especially in developing countries.

Main Text

Numerous previous clinical and experimental studies have demonstrated that PM2.5 has a clear pathogenic effect on diseases related to the respiratory and cardiovascular systems. Recent researches have pointed out that PM2.5 plays a pivotal role in the occurrence and progression of ocular surface diseases. The current studies have shown that PM2.5 may promote the appearance of conjunctivitis, keratitis, blepharitis, dry eye, meibomian gland dysfunction（MGD） and other ocular surface diseases through regulating a series of mechanisms such as inflammation, immune reaction, oxidative stress, autophagy, cell migration, and epigenetics.

Conclusions

This review aims to summarize the current research progress on the pathogenic mechanism of PM2.5-related ocular surface diseases.

Systemic Immunosuppression in Cornea and Ocular Surface Disorders: A Ready Reckoner for Ophthalmologists

Purpose: Many diseases of the cornea and ocular surface are manifestations of an underlying autoimmune process and require systemic immunosuppression for their management. These cases often present to a general ophthalmologist before being referred to an ocular immunologist or rheumatologist. However, the patients do need to be followed by the ophthalmologist to assess disease progression or for management of ocular co-morbidities and for taking care of ocular complications of the disease. Undeniably, there is a certain hesitance to promptly initiate them on systemic therapy because the literature regarding the indications, dosages, and side effects of this group of drugs is vast and dispersed.The aim of this review is to provide a source of ready reference for the general ophthalmologist as well as trainees and residents, on systemic immunosuppression for corneal and ocular surface disease. Methods: This review included 153 studies which were published as randomized controlled trials, systematic reviews, or as nonrandomized comparative studies (cohort or case-control series) on the topic of systemic immunosuppression in cornea and ocular surface disorders.Results: This review provides a concise summary of both the types of drugs and the common indications where they would be indicated, along with treatment and monitoring algorithms for each specific disease condition. The most used group of drugs are corticosteroids, which have significant side effects, particularly when administered systemically or for longer periods of time. To overcome this, steroid-sparing immunosuppressants are recommended. The four main classes of immunosuppressants used today are antimetabolites, T-cell inhibitors, alkylating agents and biologic agents. This review details the use of these drugs in ocular surface inflammation, including the dosing schedule, side effects and monitoring in allergic conjunctivitis, mucous membrane pemphigoid, peripheral ulcerative keratitis, immunological rejection against corneal allografts, anterior scleritis and aqueous deficiency dry eyes. Conclusions: This review provides an uncluttered and wholesome understanding of systemic immunosuppression in cornea and ocular surface diseases, with the hope that this will serve as a ready reckoner and help bridge the gap between ophthalmology and rheumatology for the betterment of our patients.

[Corneal perforation with tyrosine kinase inhibitor chemotherapy: REGORAFENIB]

INTRODUCTION

Tyrosine kinase inhibitors (TKIs) are active in a variety of metastatic cancers. They have a good general tolerance with mainly hepatic and dermatological side effects. Rarely, ophthalmologic side effects may occur: eyelash abnormalities, eyelids abnormalities, disorders of the ocular surface with ocular dryness or even corneal erosions that can even lead to perforation. Regorafenib is a new oral multi-targeted tyrosine kinase inhibitor that inhibits multiple protein kinases, including those involved in tumor angiogenesis, oncogenesis and tumor microenvironment.

CASE DESCRIPTION

We describe, to the best of our knowledge, the first case of complicated bilateral ulcers of corneal perforation in a patient under REGORAFENIB.

OBSERVATION

20-year-old patient with metastatic chondrosarcomas of the pelvis, mandible and thorax received chemotherapy with REGORAFENIB. A few weeks after initiation of treatment, he experienced an increased dry eye syndrome associated with bilateral corneal ulcers complicated by perforation. Despite discontinuation of chemotherapy and maximal medical and surgical treatment (iterative amniotic membrane grafts and corneal transplantation), the progression was unfavorable.

DISCUSSION

This is the first known case of corneal perforation under REGORAFENIB. The pathophysiology is multifactorial. On the one hand, this chemotherapy targets angiogenesis (VEGFR), oncogenesis (KIT, RET, RAF1, BRAF) and the tumor microenvironment (PDGFR, FGFR). On the other hand, other triggers are added, namely mixed dry eye syndrome, hypovitaminosis A (anorexia), the neurotrophic component, as well as the toxicity of chemotherapy via tears.

CONCLUSION

First described case of corneal perforation under REGORAFENIB, non-regressive at the end of chemotherapy, and despite medical and surgical treatments. Ophthalmologic surveillance is therefore necessary for patients under chemotherapy with tyrosine kinase inhibitors, as serious ocular complications, especially corneal ones, may occur.

Scleral contact lenses: Visual outcomes and tolerance. A prospective study about 98 eyes

PURPOSE

To assess the improvement in visual acuity (VA), tolerance and quality of life of patients after scleral contact lens (SCL) fitting.

MATERIAL AND METHODS

We carried out a prospective observational study conducted from April 2016 to August 2017. Patients fitted with SCL were included. For the purpose of this study, we analyzed VA and quality of life score (NEI-VFQ25) after 6 months of use.

RESULTS

We identified 98 eyes of 56 patients; the major indication for SCL fitting was keratoconus in 64.3%; the other indications were post-penetrating keratoplasty, other irregular astigmatism, severe ametropia and ocular surface disease. The mean follow-up was 10.71 months. The mean daily wearing time was 9.89±1.63 hours. Best corrected Visual acuity "BCVA" (baseline 1.11±0.37 in the right eye and 1.13±0.42 LogMar in the left eye) improved to 0.19±0.20 and 0.23±0.38 LogMar respectively in the right and left eyes after SCL wear (P=0.000). The scores on the various subscales of the NEI-VFQ 25 questionnaire were significantly higher 6 months after SCL fitting, with a mean score of 87.28±9.87 with SCL versus 39.94±11.33 without these lenses (P=0.000). In our group, no complications related to the SCL wear occurred, except for the occurrence of "loose conjunctival tissue" at the inferior limbus in one patient.

DISCUSSION

Our results complement those of several large series published on this subject. The best visual acuities were reported after correction of irregular astigmatism, in particular keratoconus. Therefore, SCL fitting has become an alternative or a precursor to penetrating keratoplasty in patients with advanced keratoconus. In the case of ocular surface disease, in addition to the improvement in VA, the comfort and recovery of the homeostasis of the ocular surface is greater, with fewer wearing complications. Hence, their inclusion in the therapeutic arsenal for severe ocular surface disease alongside the conventional treatment options.

CONCLUSION

SCL have proven their efficacy and safety in the optical correction of irregular corneas and in the management of ocular surface problems. Additional studies are needed to compare the many lenses currently available and assess optimal fitting strategies for each type of scleral lens for easier fitting procedures and better wearing comfort.

Pluripotent Stem Cells and Other Innovative Strategies for the Treatment of Ocular Surface Diseases

The cornea provides two thirds of the refractive power of the eye and protection against insults such as infection and injury. The outermost tissue of the cornea is renewed by stem cells located in the limbus. Depletion or destruction of these stem cells may lead to blinding limbal stem cell deficiency (LSCD) that concerns millions of patients around the world. Innovative strategies based on adult stem cell therapies have been developed in the recent years but they are still facing numerous unresolved issues, and the long term results can be deceiving. Today there is a clear need to improve these therapies, and/or to develop new approaches for the treatment of LSCD. Here, we review the current cell-based therapies used for the treatment of ocular diseases, and discuss the potential of pluripotent stem cells (embryonic and induced pluripotent stem cells) in corneal repair. As the secretion of paracrine factors is known to have a crucial role in maintaining stem cell homeostasis and in wound repair, we also consider the therapeutic potential of a promising novel pathway, the exosomes. Exosomes are nano-sized vesicles that have the ability to transfer RNAs and proteins to recipient cells, and several studies demonstrated their role in cell protection and wound healing. Exosomes could circumvent the hurdles of stem-cell based approaches, and they could become a strong candidate as an alternative therapy for ocular surface diseases.

The recurrence of pterygium after different modalities of surgical treatment

PURPOSE

To assess and compare the recurrence rate of pterygium after limbal stem cell transplantation versus amniotic membrane transplantation (AMT) as ocular surface reconstructing measures in recurrent pterygium, also evaluation of the use of antimetabolite drugs as adjunctive therapy for AMT.

PATIENTS AND METHODS

Prospective randomized comparative study included 60 eyes of 48 patients with recurrent pterygia. Informed consents were taken from all patients. Primary pterygium excision was performed 6-15 months ago; the cases were divided randomly into three equal groups: Group 1: included 20 eyes with excision of the pterygium and application of limbal stem cell transplantation with conjunctival autograft, group 2: included 20 eyes with excision of the pterygium followed by AMT and group 3: included 20 eyes in which surgical excision of pterygium was followed by intra-operative application of low-dose of MMC (0.05%) for 3 min then using AMT.

RESULTS

The study included 36 males and 12 females of age ranged from 28 to 52 years. The recurrence rate was 2 eyes in group 1 (10%) (limbal stem cell transplantation + conjunctival autograft), 6 eyes in group 2 (30%) (AMT) and 4 eyes (20%) in group 3 (MMC + AMT). The rate of recurrence was significantly different between the three groups (P < 0.001).

CONCLUSIONS

Limbal stem cell transplantation together with conjunctival autografting proved to be more effective in prevention of pterygium recurrence and in rapid restoration of normal epithelial morphology. MMC in addition to AMT decreases the incidence of recurrence.