The pathology of dry eye: the interaction between the ocular surface and lacrimal glands

From injury to recovery: investigating wound healing in a 3D tissue-engineered cornea equivalent

The semi-automatic generation of a multilayer cornea model was to study the process of wound healing and the influence of substances modulating wound healing. We generated in vitro corneal human tissues including epithelium and a semi automatedly produced stroma equivalent based on a hydrogel matrix. The maturation was evaluated using impedance spectroscopy, histology and immunofluorescence over 21 days. Inflicting corneal wounds by clinical excimer laser, injury was observed under treated with gentamicin and non-treated for 14 days by histology and optical coherence tomography (OCT). The semi-automated system produced a standardized corneal stroma equivalent that allowed reproducible growth of a multilayered epithelium. The histology and marker expression were comparable to human cornea. Histology confirmed epithelial wound closure 10 days after laser wounding. The wound ratio at day 3, 7, 10 was continuously increasing, day 14 indicating no significant difference to unwounded models. Gentamicin, a standard antibiotic eye drop, displayed reduced closure. In conclusion, the 3D cornea tissue model is recapitulating the human cornea and can be used as a valuable in vitro model for studying wound healing. A robust method to use the hydrogel as biocompatible material is needed. Non-destructive impedance spectroscopy and OCT allow online monitoring of the wound closure.

Extracellular Vesicles of Tears and Ocular Surface: An Enigma

PURPOSE

A stable ocular surface is crucial for maintaining ocular health by protecting against various infections. This is achieved by coordinated function of ocular structures (cornea, limbus, conjunctiva), innervation, and the tear film which forms a protective barrier over the ocular surface ensuring proper hydration, lubrication, and overall ocular comfort. This complex three-layered tear film secreted by different sources ensures its stability by adhesion to the corneal epithelium. Ocular surface fluid kinetics and tear secretion involve complex processes influenced by neural regulation, environmental factors, and molecular composition. Recent advances in cell biology and secretome has unravelled the mysteries of cellular cargo of almost every cell and system i.e. the extracellular vesicles (EVs) which facilitate intercellular communication. EVs are of different sizes, amongst which small EVs (sEVs) potentially are more informative than other EVs.

METHODS

An extensive review of literature on sEVs in tears and ocular surface was conducted.

RESULTS

Emerging literature on sEVs derived from ocular surface structures such as cornea and limbal stem cells contribute to corneal wound healing, regeneration and reduced fibrosis by the activation of specific proteins. A recent study documents that homeostasis between cornea and conjunctiva is maintained by the expression of specific genes triggering trans differentiation in diseased conditions. There is also mounting evidence on role of tear-derived sEVs in normal and diseased states. The approach in which tear layers secreted from three different sources form into a single tri-layered stable biofilm covering the entire ocular surface remains elusive. Hence not surprisingly, the tear sEVs therefore have been referred to as one entity and not attributed to any of the 3 different sources that they originate from.

CONCLUSION

This review attempts to present the recent concepts of sEVs, ocular surface, tears and highlight the gaps in our understanding of tear-derived exosomes and its potential role in homeostasis and disease conditions.

Ocular drug delivery systems based on nanotechnology: a comprehensive review for the treatment of eye diseases

Ocular drug delivery is a significant challenge due to the intricate anatomy of the eye and the various physiological barriers. Conventional therapeutic approaches, while effective to some extent, often fall short in effectively targeting ocular diseases, resulting in suboptimal therapeutic outcomes due to factors such as poor ocular bioavailability, frequent dosing requirements, systemic side effects, and limited penetration through ocular barriers. This review elucidates the eye's intricate anatomy and physiology, prevalent ocular diseases, traditional therapeutic modalities, and the inherent pharmacokinetic and pharmacodynamic limitations associated with these modalities. Subsequently, it delves into nanotechnology-based solutions, presenting breakthroughs in nanoformulations such as nanocrystals, liposomes, dendrimers, and nanoemulsions that have demonstrated enhanced drug stability, controlled release, and deeper ocular penetration. Additionally, it explores a range of nanosized carriers, including nano-structured lipid carriers, hydrogels, nanogels, nanoenzymes, microparticles, conjugates, exosomes, nanosuspensions, viral vectors, and polymeric nanoparticles, and their applications. Unique insights include emerging innovations such as nanowafers and transcorneal iontophoresis, which indicate paradigm shifts in non-invasive ocular drug delivery. Furthermore, it sheds light on the advantages and limitations of these nanotechnology-based platforms in addressing the challenges of ocular drug delivery. Though nano-based drug delivery systems are drawing increasing attention due to their potential to enhance bioavailability and therapeutic efficacy, the review ends up emphasizing the imperative need for further research to drive innovation and improve patient outcomes in ophthalmology.

A comprehensive scoping review of methodological approaches and clinical applications of tear fluid biomarkers

Tear fluid is an emerging source of disease biomarkers, drawing attention due to its quick, inexpensive, and non-invasive collection. The advancements in detection techniques enable the measurement of ultra-low biomarker levels from small sample volumes typical of tear fluid. The lack of standardized protocols for collection, processing, and analysis of tear fluid remains a significant challenge. To address this, we convened the Tear Research Network Review Taskforce in 2022 to review protocols from the past three decades, providing a comprehensive overview of the methodologies used in tear fluid biomarker research. A total of 1484 articles published from January 1974 to May 2024 from two electronic databases, Embase and Ovid MEDLINE, were reviewed. An exponential increase in the number of articles on tear fluid biomarkers was observed from 2015 onwards. The two most commonly reported collection methods were; glass capillaries (45.2%), and Schirmer's strips (25%), with glass capillary tube collection remaining the most frequent method until 2019, when Schirmer's strips became the leading method. Most articles analyzed tear fluid proteins (65%) and focused on a single analyte (32.3%). In recent years, an increase was observed in the type and number of examined analytes. The differences in the reported methodologies and protocols underscore the need for standardization and harmonization within the field of tear fluid biomarkers to minimize methodological differences and reduce variability in clinical outcomes. Consistent and detailed reporting is essential for improving the reproducibility and validity of tear fluid studies, in order to advance their potential clinical applications.

Corneal Sensory Nerve Injury Disrupts Lacrimal Gland Function by Altering Circadian Rhythms in Mice

Purpose

To investigate the impact of corneal sensory nerve injury on lacrimal gland function, focusing on mechanisms involving the superior salivatory nucleus (SSN), circadian rhythm disruption, immune microenvironment alterations, and the potential for neural regeneration.

Methods

A murine model of corneal sensory nerve injury was used to assess lacrimal gland function, with tear secretion measured using the phenol red thread test. Transcriptomic analysis of lacrimal glands examined circadian rhythm and immune-related gene expression. Basic fibroblast growth factor (bFGF) was used to promote corneal nerve regeneration, and its effects on tear secretion and nerve repair were evaluated.

Results

Corneal nerve injury resulted in a 35% reduction in tear secretion and significantly impaired SSN activity, as evidenced by a 31% decrease in c-FOS-positive neurons in choline acetyltransferase (ChAT)-expressing neurons. Transcriptomic analysis revealed significant downregulation of immune-related pathways, including Toll-like receptor (TLR), NOD-like receptor (NLR), and T-cell receptor signaling. Circadian rhythm gene expression exhibited phase shifts, with a 2.13-hour delay in peak expression and a substantial change in the number and types of rhythmic genes, which were enriched in different signaling pathways. The bFGF treatment restored tear secretion by 22% and promoted nerve regeneration, although nerve fiber density remained 74% lower than that of controls.

Conclusions

Corneal sensory nerve injury disrupts both central and peripheral circadian clock functions in the lacrimal gland, leading to reduced tear secretion and immune dysregulation. These findings highlight the novel role of circadian rhythms and neural-immune interactions in lacrimal gland dysfunction. Neural regeneration strategies, such as bFGF, offer therapeutic potential for dry eye syndrome, providing new directions for clinical intervention.

Optimizing instilled drug delivery: a scoping review of microdrops in ophthalmology

Eyedrop instillation constitutes the most commonly used ocular drug delivery method that serves for both diagnostic and therapeutic purposes. Ocular disposition and bioavailability of instilled drugs depend on the anatomy and physiology of the ocular surface as well as the physicochemical properties of the active agent. Intraocular bioavailability is positively associated with the amount of drug available onto the ocular surface and the precorneal residence time. Concerns are raised regarding systemic absorption of the instilled drugs intraocularly, percutaneously, via the conjunctiva, through the nasolacrimal system, or through the nasal, oral, and gastrointestinal mucosa. Special considerations exist regarding the anatomical features and the limited pharmacokinetic data on the pediatric population that complicate further the efficacy and systemic toxicity of the instilled medications. Both preclinical and clinical studies propose the reduction of the instilled drop volume, in the form of microdrops, as a means to enhance intraocular bioavailability of topically applied drugs, while minimizing patient discomfort and systemic adverse events. We summarize existing data on the clinical application of microdrops in a wide age range, from preterm infants to elderly adults. Studies regarding microdrops of mydriatics and ocular hypotensives show promising results in optimizing the provided everyday care.

Autologous Serum Eye Drops Diluted with Cyclosporine A 0.05% and Sodium Hyaluronate 0.1%: An Experimental Comparative Study

PURPOSE

The purpose of this study was to assess in-vitro efficacy of a suffusion of autologous serum withcyclosporine 0.05% (CsA) and sodium hyaluronate 0.1% (SH).

METHODS

The expression of proinflammatory markers interleukin 6 (IL-6) and TNF-Alpha (TNF-α) in limbal epithelial cells was evaluated. Also, assessment of the stability of epithelial growth factor and transforming growth factor-beta (EGF, TGF-β) in the 50% combinations with autologous serum (AS) was done. The characteristics (pH, density, osmolality) of the two combinations were also evaluated. Additionally, cytotoxicity effect of given test compounds was evaluated on human limbal epithelial cells (LEpiC).

RESULTS

The percentage of cells expressing IL-6 subjected to AS + SH and AS + CsA were 6.23% and 5.69% respectively. There was no significant difference in percentage of cells expressing TNF-α between the formulations (5.87%, 5.83% respectively). The growth factors; EGF and TGF-β remained stable forone month duration (on 2 and 4 weeks) at 4 °C without significant difference between the time intervals tested. The results of MTT assay suggested that limbal epithelial cells treated with AS + CsA and AS + SH combinations showed minimal toxicity however it was not significant statistically (p ≤ 0.05).

CONCLUSION

Two test combinations (AS + CsA, AS + SH) showed stable growth factors (EGF, TGF-β) and good anti-inflammatory property against pro-inflammatory markers. Also, the 2 combinations were found safe on cultured limbal epithelial cells. The novel combination of autologous serum in CsA may provide added benefit in dry eye disease (DED) through their combined anti-inflammatory and epitheliotropic effects.

A Sex-Dependent Cannabinoid CB1 Receptor Role in Circadian Tearing of the Mouse

Purpose

We have shown that cannabinoid CB1 receptors regulate both salivation and tearing, but for tearing, this regulation is sex dependent with opposing effects by sex. We investigated a potential interplay of circadian and cannabinoid regulation of tearing.

Methods

We measured cannabinoid and circadian regulation of tearing in CD1 strain mice as well as CB1 receptor protein expression using immunohistochemistry.

Results

We now report that CD1 strain mice have a circadian variation in basal tearing, differing by sex in terms of phase and amplitude. The amplitude of circadian variation in females is substantially dampened relative to males. Male CB1 receptor knockout mice do not differ from strain controls, but in female CB1 knockouts, the amplitude is enhanced and resembles that of WT males. This increased tearing is mimicked by the CB1 antagonist SR141716 (4 mg/kg, intraperitoneally [IP]), suggesting that tonic CB1 activation dampens female circadian tearing. Consistent with this, the cannabinoid receptor agonist CP55940 (0.5 mg/kg, IP) decreases tearing during the rest phase but increases tearing during the active phase in females. CB1 protein expression also differs by sex. While both males and females have CB1 receptors in parasympathetic inputs to the lacrimal gland, in female lacrimal glands, CB1 is also detected in myoepithethial cells.

Conclusions

Mice have a sex-dependent circadian cycle of tearing. The endogenous cannabinoid signaling system appears to mediate some circadian effects, albeit in a sex-dependent manner and via distinct cellular targets.

Correlation between meibomian gland dysfunction and sebaceous adenitis in dogs

BACKGROUND

Sebaceous adenitis (SA) is an immune-mediated disease targeting the sebaceous glands. Meibomian gland dysfunction is a disease affecting meibomian glands with inflammatory features. Sebaceous and meibomian glands share anatomical, physiological and embryological similarities. The involvement of meibomian glands in dogs with SA is currently unknown.

OBJECTIVES

To evaluate meibomian glands in dogs affected by SA and compare them with healthy dogs.

ANIMALS

Eighteen dogs were enrolled. Nine dogs with SA were retrospectively identified from clinical records and represented the case group. Nine healthy, breed- and age-matched dogs were prospectively enrolled in the control group.

MATERIALS AND METHODS

Both groups underwent dermatological examination, Schirmer tear test-1 (STT-1), tear meniscus height (TMH), slit-lamp biomicroscopy, interferometry (INT) and noncontact infrared meibography (NIM).

RESULTS

One third of SA dogs presented subepithelial crystalline opacities. No significant difference between groups was observed in TMH (p = 0.944) and STT-1 values (p = 0.066). INT (p = 0.016) and NIM grades (p = 0.010) were significantly higher and lower in the SA group compared to the control group, respectively. INT values decreased with age (η = 0.930), while NIM scores (η = 0.935) increased.

CONCLUSIONS

Clinical Relevance: Subepithelial crystalline opacities in SA dogs might reflect a reduced tear film quality. In the absence of standardised methods, INT and NIM proved to be noninvasive and useful methods to examine meibomian glands. Dogs with SA showed a thinner lacrimal lipid layer and more severe meibomian gland abnormalities than control dogs, which seemed to progress with age.

Innervation in corneal bioengineering

Given the crucial role nerves play in maintaining corneal function and integrity, the ability of bioengineered cornea to demonstrate functional nerve regeneration directly influences their longevity and stability. Despite advances in biofabrication techniques and an increasing appreciation of the importance of neural innervation, to this day none have completely replicated the complexity and functionality of the cornea with successful innervation. This review evaluates the materials and fabrication techniques used to produce and enhance innervation in bioengineered cornea. Approaches to facilitating innervation are discussed and methods of assessing innervation compared. Finally, current challenges and future directions for innervated bioengineered cornea are presented, providing guidance for future work. STATEMENT OF SIGNIFICANCE: The functional nerve regeneration in bioengineered corneas directly influences their longevity and stability. Despite advancements in biofabrication techniques and growing recognition of the importance of neural innervation for bioengineered cornea, there remains a lack of comprehensive reviews on this topic. This review addresses the critical gap by evaluating the materials and fabrication techniques employed to promote innervation in bioengineered corneas. Additionally, we discuss various approaches to enhancing innervation, compare assessment methods, and examine both in vitro and in vivo responses. By providing a comprehensive overview of the current state of research and highlighting challenges and future directions, this review aims to provide guidance for inducing innervation of bioengineered cornea.

The involvement of aquaporin 5 in the inflammatory response of primary Sjogren's syndrome dry eye: potential therapeutic targets exploration

Sjogren's syndrome (SS) is a chronic autoimmune disease. Mainly due to the infiltration of lymphoplasmic cells into the exocrine glands, especially the salivary glands and lacrimal glands, resulting in reduced tear and saliva secretion. Reduced tear flow can trigger Sjogren's syndrome dry eye (SSDE). Although the pathophysiology of SSDE xerosis remains incompletely understood, recent advances have identified aquaporin-5 (AQP5) as a critical factor in dysregulation of the exocrine gland and epithelium, influencing the clinical presentation of SSDE through modulation of inflammatory microenvironment and tear secretion processes. This review aims to explore AQP5 regulatory mechanisms in SSDE and analyze its potential as a therapeutic target, providing new directions for SSDE treatment.

Modified Sodium hyaluronate conjugated to riboflavin (Har® 0.1 %) as lubricant eyedrops in the treatment of dry eye: A prospective randomised study

Background

This study evaluates the therapeutic efficacy of HAr® (a novel ophthalmic solution containing modified hyaluronic acid covalently linked to riboflavin) compared to hyaluronic acid eye drops in patients with dry eye disease (DED).

Methods

Sixteen consecutive patients with bilateral medium to severe DED were divided into two groups. Group 1 received HAr® 0.1 % (Ribohyal®), while Group 2 received HA 0.1 % eye drops. Parameters such as Ocular Surface Disease Index (OSDI) score, osmolarity, break-up time (BUT), non-invasive BUT (NIBUT), tear meniscus measurement, Schirmer test, and Oxford Staining were evaluated. This study has been successfully registered on ClinicalTrials.gov public (Identifier NCT06122428).

Results

The Ribohyal group showed faster improvement in OSDI scores, with a statistically significant difference at 2 h (mean classification difference: -51.75; p = 0.0003). Photophobia significantly reduced at 2 h, 4 weeks, and 8 weeks in the Ribohyal group compared to baseline (p < 0.0001). Osmolarity improved significantly after 8 weeks in both groups (p < 0.0001).

Conclusions

HAr® 0.1 % (Ribohyal®) effectively reduced DED symptoms and improved photophobia within 2 h of instillation, lasting up to 8 weeks.

Quantitative evaluation of morphological and functional changes in meibomian glands and lipid layer thickness in patients with and without keratoconus

PURPOSE

To quantitatively evaluate the morphological parameters of meibomian glands (MGs) and lipid layer thickness (LLT) in patients with keratoconus (KC).

METHODS

In this prospective, cross-sectional study, 164 eyes of 164 keratoconus patients and 64 eyes of 64 age-matched control subjects were included. An advanced automatic MG analyzer was used to quantitatively measure the morphological and functional parameters of MGs. Morphological and functional parameters of MGs, LLT, and other ocular surface parameters were compared between the control and KC groups.

RESULTS

The mean meibomian gland diameter, length, square, and gland area ratio (GA) were all significantly decreased in the KC group (all P < 0.05), while no significant difference was observed in the gland tortuosity index (TI) and gland signal index (SI) between the KC and control groups (all P > 0.05). There was no significant difference in the number of total and incomplete blinking among patients with different stages of keratoconus (all P > 0.05). The gland diameter, square, and TI were all negatively associated with KC severity (all P < 0.05), while no significant difference was observed among all stages of KC in gland length, GA, and SI (all P > 0.05). Moreover, the LLTs were positively correlated with the gland diameter, square, GA, and TI and negatively correlated with anterior corneal curvature or KC severity (all P < 0.05).

CONCLUSIONS

Atrophic morphological changes in the meibomian glands were closely correlated with the severity of keratoconus. Gland diameter may be a sensitive functional morphology metric of meibomian glands in patients with keratoconus.

Blood-Derived Eye Drops for the Treatment of Corneal Neuropathic Pain

Blood-derived preparations, including autologous or allogenic serum, umbilical cord serum/plasma, and platelet-rich plasma eye drops, contain various growth factors, cytokines, and immunoglobulins that resemble natural tears. These components play important roles in corneal cell migration, proliferation, and wound healing. Blood-derived eye drops have demonstrated clinical effectiveness across a spectrum of ocular surface conditions, encompassing dry eye disease, Sjögren's syndrome, graft-versus-host disease, and neuropathic corneal pain (NCP). Currently, management of NCP remains challenging. The emergence of blood-derived eye drops represents a promising therapeutic approach. In this review, we discuss the benefits and limitations of different blood-derived eye drops, their mechanisms of action, and treatment efficacy in patients with NCP. Several studies have demonstrated the clinical efficacy of autologous serum eye drops in relieving pain and pain-like symptoms, such as allodynia and photoallodynia. Corneal nerve parameters were also significantly improved, as evidenced by increased nerve fiber density, length, nerve reflectivity, and tortuosity, as well as a decreased occurrence of beading and neuromas after the treatment. The extent of nerve regeneration correlated with improvement in patient-reported photoallodynia. Cord plasma eye drops also show potential for symptom alleviation and corneal nerve regeneration. Future directions for clinical practice and research involve standardizing preparation protocols, establishing treatment guidelines, elucidating underlying mechanisms, conducting long-term clinical trials, and implementing cost-effective measures such as scaling up manufacturing. With ongoing advancements, blood-derived eye drops hold promise as a valuable therapeutic option for patients suffering from NCP.

Differential Impact of 0.01% and 0.05% Atropine Eyedrops on Ocular Surface in Young Adults

Purpose

To evaluate the effect of low-concentration (0.01% and 0.05%) atropine eyedrops on ocular surface characteristics in young adults.

Methods

Twenty-six myopic students aged 18 to 30 years were randomly assigned to receive either 0.01% or 0.05% atropine once nightly for 14 days, followed by cessation, with a ≥14-day interval between each administration. Assessments were conducted one, two, seven, and 14 days after using atropine with corresponding timepoints after atropine cessation. Tear meniscus height and first and average noninvasive keratograph tear film breakup time (NIKBUT-first, NIKBUT-average) were measured using Keratograph 5M, whereas the objective scatter index (OSI) was measured by OQAS II devices; the ocular surface disease index (OSDI) score was also obtained.

Results

The mean OSI peaked after two days of administration of 0.05% atropine (β = 0.51, P = 0.001), accompanied by significant decreases in NIKBUT-first (β = -7.73, P < 0.001) and NIKBUT-average (β = -8.10, P < 0.001); the OSDI peaked after 14 days (β = 15.41, P < 0.001). The above parameters returned to baseline one week after atropine discontinuation (all P > 0.05). NIKBUT-first and NIKBUT-average reached their lowest points after 14 days of 0.01% atropine administration (NIKBUT-first: β = -4.46, P = 0.005; NIKBUT-average: β = -4.42, P = 0.001), but those significant changes were diminished once atropine treatment stopped.

Conclusions

Young adult myopes experienced a significant but temporary impact on the ocular surface with 0.05% atropine administration, whereas 0.01% atropine had a minimal effect.

Translational Relevance

The investigation of the ocular surface effects of different concentrations of atropine may inform evidence-based clinical decisions regarding myopia control in young adults.

Cornea Classic: Stern, Beuerman, Fox, Gao, Mircheff, and Pflugfelder, "The Pathology of Dry Eye: The Interaction Between the Ocular Surface and Lacrimal Glands" (1998)

ABSTRACT

In one of the most frequently cited articles from Cornea , Stern et al's "The pathology of dry eye: the interaction between the ocular surface and lacrimal glands" (1998) revolutionized our current understanding of the pathophysiology of dry eye disease.

One Soul and Several Faces of Evaporative Dry Eye Disease

The ocular surface system interacts with, reacts with, and adapts to the daily continuous insults, trauma, and stimuli caused by direct exposure to the atmosphere and environment. Several tissue and para-inflammatory mechanisms interact to guarantee such an ultimate function, hence maintaining its healthy homeostatic equilibrium. Evaporation seriously affects the homeostasis of the system, thereby becoming a critical trigger in the pathogenesis of the vicious cycle of dry eye disease (DED). Tear film lipid composition, distribution, spreading, and efficiency are crucial factors in controlling water evaporation, and are involved in the onset of the hyperosmolar and inflammatory cascades of DED. The structure of tear film lipids, and subsequently the tear film, have a considerable impact on tears' properties and main functions, leading to a peculiar clinical picture and specific management.

The impact of prolonged face mask use on ocular surface health during COVID-19 pandemic: a clinical, and conjunctiva impression cytology study

PURPOSE

To investigate the relationship between prolonged face mask use and ocular surface health utilizing conjunctival impression cytology, the Schirmer test, the tear break-up time (TBUT) test, and the ocular surface disease index (OSDI) questionnaire.

METHODS

In this cross-sectional prospective study, individuals who used face masks for at least eight hours per day for at least six months were compared to healthy volunteers who used face masks for no more than one hour per day. Each participant completed an OSDI questionnaire. The Schirmer test (under anesthesia), the TBUT test, and conjunctiva impression cytology analysis according to the Nelson classification method were performed on each participant.

RESULTS

This study included 102 (49 male, 53 female) face mask users with an average age of 33.29 ± 7.71 years and 110 (60 male, 50 female) healthy controls with an average age of 32.96 ± 7.10 years (p = 0.746). The total OSDI score was significantly higher in face mask users than the control group (25.18 ± 3.54 vs 9.46 ± 2.13, p < 0.001). The mean Schirmer test value and TBUT were significantly lower in the study group than the control group (p < 0.001, p < 0.001). There was a statistically significant difference between the two groups in total score and stage of the Nelson classification system (p < 0.001, and p = 0.024, respectively). All conjunctiva impression cytology assessments, including cellularity, cell-cell contact, nucleus/cytoplasma ratio, goblet cell amount, and metaplasia, revealed statistically significant deterioration in the study group compared to the control group (p < 0.001, p = 0.025, p < 0.001, p < 0.001, and p < 0.001, respectively).

CONCLUSION

The prolonged use of face masks leads to dry eyes. The findings of conjunctiva impression cytology indicate the role of inflammation in the pathogenesis of mask associated dry eye.

New advances in medical management of dry eye: optimizing treatment strategies for enhanced relief

PURPOSE

Dry eye disease (DED) is a prevalent ocular surface disease that is conventionally characterized by tear film hyperosmolarity and instability. This review presents a summarized classification of DED, followed by a comprehensive discussion of the most recent topical and systemic medications and clinical recommendations for selecting the most appropriate option for each patient.

METHODS

An extensive literature search was conducted on electronic databases, such as PubMed, Scopus, and Web of Science, using keywords including "dry eye syndrome," "ocular surface disease," "medical management," "artificial tears," "topical immunomodulators," and "meibomian gland dysfunction."

RESULTS

The underlying reasons for DED can range from insufficient aqueous tear production to increased tear evaporation. Recent literature has provided a more in-depth understanding of the pathophysiology of DED by examining the tear film's lipid, aqueous, and mucin layers. However, despite these advancements, medical management of patients with symptomatic DED has not fully reflected this modernized knowledge of its pathophysiology.

CONCLUSION

To develop a rationalized strategy for treating DED, it is crucial to have updated knowledge of therapeutic options, their mechanisms of actions, and indications based on the DED type and underlying causes.

Recent progress of nanomedicine in managing dry eye disease

Background

Dry eye disease (DED) is a commonly reported ocular complaint that has garnered significant attention in recent research. The global occurrence of DED ranges from 5% to 50%, impacting a substantial proportion of individuals worldwide with increasing frequency. Although topical administration remains the mainstream drug delivery method for ocular diseases, it suffers from drawbacks such as low bioavailability, rapid drug metabolism, and frequent administration requirements. Fortunately, the advancements in nanomedicine offer effective solutions to address the aforementioned issues and provide significant assistance in the treatment of DED.

Main text

DED is considered a multifactorial disease of the ocular surface and tear film, in which the integrity of tear film function and structure plays a crucial role in maintaining the homeostasis of the ocular surface. The conventional treatment for DED involves the utilization of artificial tear products, cyclosporin, corticosteroids, mucin secretagogues, and nonsteroidal anti-inflammatory drugs. Furthermore, nanomedicine is presently a significant field of study, with numerous clinical trials underway for various nanotherapeutics including nanoemulsions, nanosuspensions, liposomes, and micelles. Notably, some of these innovative nanoformulations have already received FDA approval as novel remedies for DED, and the advancement of nanomedicine is poised to offer enhanced prospects to solve the shortcomings of existing treatments for DED partially.

Conclusions

This article provides an overview of the latest advancements in nanomedicine for DED treatment, while the field of DED treatment is expected to witness a remarkable breakthrough shortly with the development of nanomedicine, bringing promising prospects for patients worldwide suffering conditions.

Analysis of Cytokine and Chemokine Level in Tear Film in Keratoconus Patients before and after Corneal Cross-Linking (CXL) Treatment

Keratoconus (KC) is a degenerative corneal disorder whose aetiology remains unknown. The aim of our study was to analyse the expressions of cytokines and chemokines in KC patients before and after specified time intervals after corneal cross-linking (CXL) treatment to better understand the molecular mechanisms occurring before and after CXL in KC patients process of corneal regeneration.; Tear samples were gathered from 52 participants immediately after the CXL procedure and during the 12-month follow-up period. All patients underwent a detailed ophthalmological examination and tear samples were collected before and after CXL at regular intervals: 1 day before and after the surgery, at the day 7 visit, and at 1, 3, 6, 9, and 12 months after CXL. The control group consisted of 20 healthy people. 10 patients were women (50%) and 10 were men (50%). The mean age was 30 ± 3 years of age. Tear analysis was performed using the Bio-Plex 3D Suspension Array System. Corneal topography parameters measured by Scheimpflug Camera included: keratometry values (Ks, Kf), PI-Apex, PI-Thinnest, Cylinder.; All the 12 months post-op values of the KC patients' topographic measurements were significantly lower than the pre-op. As for the tear cytokine levels comparison between the patient and control groups, cytokine levels of TNF-α, IL-6, and CXCL-10, among others, were detected in lower amounts in the KC group. The pre-op level of IL-6 exhibited a significant increase the day after CXL, whereas comparing the day after the procedure to 12 months after CXL, this showed a significant decrease. Both TNF-α and IL-1 showed a significant decrease compared to the day before and after CXL. We observed significantly higher levels of IL-1β, IL-10, IFN-γ and TNF-α in moderate and severe keratoconus than in mild keratoconus (p < 0.05). We also demonstrated a statistically significant positive correlation between both pre-op and 12 months after CXL TNF-α, IFN-γ, IL-6 and Ks and Kf values (p < 0.05, r > 0); Alterations of inflammatory mediators in tear fluid after CXL link with topographic changes and may contribute to the development and progression of KC.

Amlodipine Ocular Delivery Restores Ferning Patterns and Reduces Intensity of Glycosylated Peak of Carrageenan-Induced Tear Fluid: An In-Silico Flexible Docking with IL-β1

BACKGROUND

The tear ferning test can be an easy clinical procedure for the evaluation and characterization of the ocular tear film.

OBJECTIVE

The objective of this study was to examine the restoration of tear ferning patterns and reduction of glycosylation peak after amlodipine application in carrageenan-induced conjunctivitis.

METHODS

At the rabbit's upper palpebral region, carrageenan was injected for cytokine-mediated conjunctivitis. Ferning pattern and glycosylation of the tear fluid were characterized using various instrumental analyses. The effect of amlodipine was also examined after ocular instillation and flexible docking studies.

RESULTS

Optical microscopy showed a disrupted ferning of the tear collected from the inflamed eye. FTIR of the induced tear fluid exhibited peaks within 1000-1200 cm-1, which might be due to the protein glycosylation absent in the normal tear spectrogram. The glycosylation peak reduced significantly in the tear sample collected from the amlodipine-treated group. Corresponding energy dispersive analysis showed the presence of sulphur, indicating protein leakage from the lacrimal gland in the induced group. The disappearance of sulphur from the treated group indicated its remedial effect. The flexible docking studies revealed a stronger binding mode of amlodipine with Interleukin-1β (IL-1β). The reduction in the intensity of the glycosylated peak and the restoration offering are probably due to suppression of IL-1β.

CONCLUSION

This study may be helpful in obtaining primary information for drug discovery to be effective against IL-1β and proving tear fluid as a novel diagnostic biomarker.

Berberine ameliorate inflammation and apoptosis via modulating PI3K/AKT/NFκB and MAPK pathway on dry eye

BACKGROUND

Dry eye disease (DED) is a multifactorial disease in ocular surface, and inflammation plays an etiological role. Berberine (BBR) has shown efficacy in treating inflammatory diseases. Yet, there was no adequate information related to the therapeutic effects of BBR for DED.

PURPOSE

To detect the effects and explore the potential mechanisms of BBR on DED.

STUDY DESIGN

In vitro, in vivo study and network pharmacology analysis were involved.

METHOD

The human corneal epithelium cells viability was evaluated with different concentrations of BBR. Dry eye murine model was established by exposing to the desiccating stress, and Ciclosporin (CSA), BBR eye drops or vehicle were topical administration for 7 days. The phenol red cotton tests, Oregon-green-dextran staining and Periodic acid-Schiff staining were performed and evaluated the dry eye after treatment. Inflammation and apoptosis levels of ocular surface were quantified. The potential targets related to berberine and dry eye were collected from databases. The Protein-Protein interaction network analysis and GO & KEGG enrichment analysis were realized by STRING database, Metascape platform and Cytoscape software to find core targets and signaling pathways. The SchrÖdinger software was used to molecular docking and PyMOL software to visualization. Finally, the levels of PI3K/AKT/NFκB and MAPK pathways were detected.

RESULT

The data revealed BBR could rescue impaired HCE under hyperosmotic conditions. In addition, BBR eye drops could ameliorate dry eye. And BBR eye drops suppressed the inflammatory factors and CD4+T cells infiltration in conjunctiva. Besides, BBR eye drops protected ocular surface by avoiding the severe apoptosis and decreasing the level of MMP-3 and MMP-9. 148 common targets intersection between BBR and dry eye were found via network pharmacology analysis. Core proteins and core pathways were identified through PPI and GO&KEGG enrichment analysis. Molecular docking displayed excellent binding between BBR and those core targets. Finally, in vivo study verified that BBR eye drops had a therapeutic effect in dry eye by inhibiting PI3K/AKT/NFκB and MAPK pathways.

CONCLUSION

The research provided convincing evidence that BBR could be a candidate drug for dry eye.

Application of iontophoresis in ophthalmic practice: an innovative strategy to deliver drugs into the eye

Delivery of drugs to special locations of ocular lesions, while minimizing systemic and local toxic effects, is recognized as a critical challenge in the ophthalmic practice. The special anatomy and physiology barriers within the eyeball entail effective drug delivery systems. Emerging attempts in drug delivery has led to developments in ocular iontophoresis, which acts as a noninvasive technology to enhance drug penetration using a small electric current. This technique offers greater flexibility to deliver desired drug dose in a controlled and tolerable manner. In previous studies, this technique has been testified to deliver antibiotics, corticoid, proteins and other gene drugs into the eye with the potency of treating or alleviating diverse ophthalmological diseases including uveitis, cataract, retinoblastoma, herpes simplex and cytomegalovirus retinitis (CMVR), etc. In this review, we will introduce the recent developments in iontophoresis device. We also summarize the latest progress in coulomb controlled iontophoresis (CCI), hydrogel ionic circuit (HIC) and EyeGate II delivery system (EGDS), as well as overview the potential toxicity of iontophoresis. We will discuss these factors that affect the efficacy of iontophoresis experiments, and focus on the latest progress in its clinical application in the treatment of eye diseases.

Efficacy of Omega-3 Intake in Managing Dry Eye Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

To explore the efficacy of omega-3 fatty acids (FAs) on patients suffering from dry eye disease (DED), a complex inflammatory condition, we reviewed data from PubMed, Embase, ClinicalTrials.gov, Web of Science, and Cochrane CENTRAL in the past 10 years (2013 to 2023). These sources provided randomized clinical trials (RCTs) that examined the efficacy of omega-3 FAs on DED patients with accessible pre- and post-intervention data, excluding trials with overlapping participants, without omega-3 supplementation, or those lacking placebo control or quantitative assessments. Two independent reviewers extracted data related to dry eye symptom scores, tear break-up time (TBUT), Schirmer's tests, osmolarity, and corneal fluorescein staining (CFS), and the results were analyzed by Comprehensive Meta-Analysis software version 4. We incorporated 19 related RCTs assessed by the Cochrane Risk of Bias tool, encompassing 4246 DED patients with various etiologies. Patients given omega-3 treatment demonstrated more significant improvements in dry eye symptoms (Hedges' g = -1.047; p < 0.001), TBUT [standardized mean difference (SMD) = -0.939; p < 0.001], scores from the Schirmer test (SMD = -0.372; p < 0.001), CFS (SMD = -0.299; p = 0.037), and osmolarity (SMD = -0.721; p < 0.001) compared to those on a placebo regimen. In the meta-regression analysis of DED symptoms, the daily dose of omega-3 (coefficient = -0.0005, p = 0.002), duration of omega-3 intake (coefficient = -0.1399, p = 0.021), and percentage of eicosapentaenoic acid (EPA) (coefficient = -0.0154, p < 0.001) exhibited a significant positive correlation with a reduction in dry eye symptom scores. Apart from CFS, similar trends were noted in TBUT, Schirmer tests, and osmolarity scores. Based on the evidence, omega-3 FAs effectively reduce DED symptoms, especially in high doses, for a long duration, and with increased EPA levels. However, given the heterogeneity in study results and diverse patient characteristics, caution is needed in generalizing these findings. In conclusion, omega-3 FA supplementation is still recommended for DED management in clinical settings.

Aquaporins in lacrimal glands and their role in dry eye disease

Aging is the most important known risk factor for dry eye is aging, which is associated with changes in the structure and function of the lacrimal gland (LG) and characterized by atrophy, duct blocking lymphocyte infiltration, and reduced protein secretion. Aquaporins (AQP) have been proposed as a potential producer of exocrine gland fluids since exocrine secretion depends on the mobility of water. Therefore, the main topics of this review will be the expression, localization, and function of AQPs in LG. In addition, we review the mechanisms of fluid transport in exocrine gland fluid secretion and discuss the potential role of AQPs in dry eye.

Pathohistological features of the aging human lacrimal gland

AIM

To assess sex-related differences in the pathohistological features of the human lacrimal gland and to investigate age-related and sex-related differences in stereologically measured volume density of the secretory tissue, connective tissue, and fat.

METHODS

We performed an observational analysis of acinar atrophy, periacinar fibrosis, periductal fibrosis, ductal dilation, ductal proliferation, fatty infiltration, and lymphocyte infiltration of hematoxylin and eosin-stained lacrimal gland samples from 81 cornea donors. Stereological analysis of the volume density of the secretory tissue, connective tissue, and fat was performed on samples from 66 donors.

RESULTS

Up to 69% of all samples showed degenerative changes. Female samples had a higher frequency of all observed degenerative changes, except ductal dilation. While acinar atrophy was significantly more prevalent in women, ductal dilation was significantly more prevalent in men. Stereological analysis indicated lower portions of acini and higher portions of connective tissue and fat, as well as a more pronounced age-related progression of degenerative changes in female samples.

CONCLUSION

Female lacrimal glands are more susceptible to degeneration, and this susceptibility could play an important role in the higher incidence of dry eye disease in older women. A further stereological analysis using more samples from younger age groups is needed to elucidate age-related and sex-related differences in the structure of the human lacrimal gland and their impact on dry eye disease.

Influence of Vitreoretinal Surgery on Ocular Surface Dynamics Using Keratograph 5M

PURPOSE

To evaluate changes of ocular surface dynamics using Keratograph 5M for 3 months after vitreoretinal surgery.

METHODS

Eighty-three patients were divided into three groups: phacoemulsification group, vitrectomy group, and combined group. Keratograph 5M was performed for all patients at 1 week, 1 month, and 3 months after the surgery. Ocular surface dynamics parameters measured by Keratograph 5M, including noninvasive keratograph first tear film breakup time (NifBUT), noninvasive keratograph average tear film breakup time (NiaBUT), and tear meniscus height (TMH) were compared among the three groups over time.

RESULTS

The mean age of all patients (46 men and 37 women) was 62.2 ± 8.4 years. NifBUT and NiaBUT were significantly decreased at 1 week after surgery compared to those at baseline in all three groups (all p < 0.001). NifBUT and NiaBUT in the phacoemulsification group almost recovered to the preoperative level, while those in the vitrectomy group and the combined group were still significantly less than those at baseline. NifBUT and NiaBUT in the phacoemulsification group were significantly longer than those in the vitrectomy group and the combined group at 3 months. After 1 week, TMHs were significantly higher in the vitrectomy group (p = 0.001) and the combined group (p = 0.022) than in the phacoemulsification group, while TMHs were significantly less in the vitrectomy group (p = 0.010) and the combined group (p < 0.001) than in the phacoemulsification group at 3 months after surgery.

CONCLUSIONS

These results suggest that vitreoretinal surgery could induce alteration of ocular surface dynamics for 3 months. The vitrectomy group and the combined group showed tear film instability compared to the cataract surgery alone group. Patients who underwent vitreoretinal surgery experienced more severe dry eye syndrome symptoms than those who underwent cataract surgery. Thus, managing dry eye syndrome after vitreoretinal surgery should be considered important for patients.

Evaluation of the Efficacy and Safety of Topical 0.05% Cyclosporine Eye Drops (II) in the Treatment of Dry Eye Associated with Primary Sjögren's Syndrome

PURPOSE

To evaluate the efficacy and safety of 0.05% cyclosporine eye drops (II) for the treatment of primary Sjögren's syndrome-associated dry eye (PSSDE).

METHODS

Sixty patients with PSSDE were randomly divided into three groups, received treatment with 0.05% cyclosporine (C group), artificial tears (S group) or their combination (CS group). The evaluation indicators were evaluated at baseline and at weeks 2, 4 and 12.

RESULTS

The symptoms of C and CS groups were reduced significantly. The signs [schirmer I test (F = 4.838, p = .011), ocular staining score (F = 7.961, p = .001) and tear break-up time (F = 9.283, p < .001)] were significantly different between S and C groups as well as S and CS groups. The tear meniscus height (F = 3.197, p = .048) was significantly different between S and CS groups. No serious adverse events occurred.

CONCLUSION

0.05% cyclosporine is an effective and safe treatment for patients with PSSDE.

Neurotrophic keratopathy: An updated understanding

PURPOSE

To propose an updated definition and staging system for neurotrophic keratopathy (NK) and provide consensus on diagnosis and treatment.

METHODS

A study group was convened to review the data pertinent to NK using a modified nominal group process. They proposed an updated definition for NK and a new 6-step staging system (Neurotrophic Keratopathy Study Group [NKSG] Classification) that can be used in conjunction with the different treatment options available currently or in the future.

RESULTS

NK is defined as the dysfunction of corneal innervation that results in dysregulation of corneal and/or cellular function. It is characterized by loss of corneal sensation and neuronal homeostasis, leading to eventual corneal epithelial breakdown and ultimately keratolysis if untreated. The NKSG classification emphasizes verifying corneal sensation early and distinguishes different epithelial and stromal aspects of NK with the following stages: stage 1 (altered sensation without keratopathy), stage 2 (epitheliopathy/punctate epithelial keratopathy [PEK] without stromal haze), stage 3 (persistent/recurrent epithelial defects without stromal haze), stage 4 (epitheliopathy/PEK or persistent/recurrent epithelial defects with stromal haze), stage 5 (persistent/recurrent epithelial defect with corneal ulceration), and stage 6 (corneal perforation). Treatment consists of a variety of modalities (both indirect and direct).

CONCLUSIONS

This updated definition and staging system will provide clinicians with the necessary information to diagnose and treat NK at an early stage before it becomes a sight-threatening disorder. It also provides a framework for evaluating current and future treatment options at distinct stages of the disease.

Open-Source Automated Segmentation of Neuronal Structures in Corneal Confocal Microscopy Images of the Subbasal Nerve Plexus With Accuracy on Par With Human Segmentation

PURPOSE

The aim of this study was to perform automated segmentation of corneal nerves and other structures in corneal confocal microscopy (CCM) images of the subbasal nerve plexus (SNP) in eyes with ocular surface diseases (OSDs).

METHODS

A deep learning-based 2-stage algorithm was designed to perform segmentation of SNP features. In the first stage, to address applanation artifacts, a generative adversarial network-enabled deep network was constructed to identify 3 neighboring corneal layers on each CCM image: epithelium, SNP, and stroma. This network was trained/validated on 470 images of each layer from 73 individuals. The segmented SNP regions were further classified in the second stage by another deep network as follows: background, nerve, neuroma, and immune cells. Twenty-one-fold cross-validation was used to assess the performance of the overall algorithm on a separate data set of 207 manually segmented SNP images from 43 patients with OSD.

RESULTS

For the background, nerve, neuroma, and immune cell classes, the Dice similarity coefficients of the proposed automatic method were 0.992, 0.814, 0.748, and 0.736, respectively. The performance metrics for automatic segmentations were statistically better or equal as compared to human segmentation. In addition, the resulting clinical metrics had good to excellent intraclass correlation coefficients between automatic and human segmentations.

CONCLUSIONS

The proposed automatic method can reliably segment potential CCM biomarkers of OSD onset and progression with accuracy on par with human gradings in real clinical data, which frequently exhibited image acquisition artifacts. To facilitate future studies on OSD, we made our data set and algorithms freely available online as an open-source software package.

Regulation of Axon Guidance by Slit2 and Netrin-1 Signaling in the Lacrimal Gland of Aqp5 Knockout Mice

Purpose

Dry eye disease (DED) is multifactorial and associated with nerve abnormalities. We explored an Aquaporin 5 (AQP5)-deficiency-induced JunB activation mechanism, which causes abnormal lacrimal gland (LG) nerve distribution through Slit2 upregulation and Netrin-1 repression.

Methods

Aqp5 knockout (Aqp5-/-) and wild-type (Aqp5+/+) mice were studied. LGs were permeabilized and stained with neuronal class III β-tubulin, tyrosine hydroxylase (TH), vasoactive intestinal peptide (VIP), and calcitonin gene-related peptide (CGRP). Whole-mount images were acquired through tissue clearing and 3D fluorescence imaging. Mouse primary trigeminal ganglion (TG) neurons were treated with LG extracts and Netrin-1/Slit2 neutralizing antibody. Transcription factor (TF) prediction and chromatin immunoprecipitation-polymerase chain reaction (ChIP-PCR) experiments verified the JunB binding and regulatory effect on Netrin-1 and Slit2.

Results

Three-dimensional tissue and section immunofluorescence showed reduced LG nerves in Aqp5-/- mice, with sympathetic and sensory nerves significantly decreased. Netrin-1 was reduced and Slit2 increased in Aqp5-/- mice LGs. Aqp5+/+ mice LG tissue extracts (TEs) promoted Aqp5-/- TG neurons axon growth, but Netrin-1 neutralizing antibody (NAb) could inhibit that promotion. Aqp5-/- mice LG TEs inhibited Aqp5+/+ TG axon growth, but Slit2 NAb alleviated that inhibition. Furthermore, JunB, a Netrin-1 and Slit2 TF, could bind them and regulate their expression. SR11302, meanwhile, reversed the Netrin-1 and Slit2 shifts caused by AQP5 deficiency.

Conclusions

AQP5 deficiency causes LG nerve abnormalities. Persistent JunB activation, the common denominator for Netrin-1 suppression and Slit2 induction, was found in Aqp5-/- mice LG epithelial cells. This affected sensory and sympathetic nerve fibers' distribution in LGs. Our findings provide insights into preventing, reversing, and treating DED.

The Effects of Sargassum horneri Extract and Fucoidan on Tear Hyposecretion and Ocular Surface Injury in Rats with Dry Eye Diseases

Hyperosmotic stress caused by tear hyposection is a leading cause of dry eye disease. We investigated the prevention of dry eye disease in corneal epithelial cells and in rats that were induced to develop dry eye disease via unilateral excision of their exorbital lacrimal gland using Sargassum horneri extract (AB_SH) and its bioactive component fucoidan. Oral administration of AB_SH (250 mg/kg and 500 mg/kg) and fucoidan (100 mg/kg) was conducted for 7 days. In order to measure tear secretion, phenol red thread tear tests were performed along with corneal irregularity measurements. The apoptotic injury in the cornea and the lacrimal gland was evaluated using TUNEL staining. AB_SH and fucoidan were shown to suppress apoptosis and the expression of apoptosis-related proteins in human corneal epithelial cells under hyperosmotic conditions. Oral administration of AB_SH and fucoidan attenuated tear hyposecretion and corneal irregularity in the lacrimal gland-excised rats. In addition, AB_SH and fucoidan also reduced apoptosis in the cornea and lacrimal gland. This study suggests that S. horneri extract and fucoidan can effectively ameliorate dry eye disease by suppressing the apoptosis of ocular tissues.

Eyes on Topical Ocular Disposition: The Considered Design of a Lead Janus Kinase (JAK) Inhibitor That Utilizes a Unique Azetidin-3-Amino Bridging Scaffold to Attenuate Off-Target Kinase Activity, While Driving Potency and Aqueous Solubility

An unmet medical need remains for patients suffering from dry eye disease (DED). A fast-acting, better-tolerated noncorticosteroid anti-inflammatory eye drop could improve patient outcomes and quality of life. Herein, we describe a small-molecule drug discovery effort to identify novel, potent, and water-soluble JAK inhibitors as immunomodulating agents for topical ocular disposition. A focused library of known 3-(4-(2-(arylamino)pyrimidin-4-yl)-1H-pyrazol-1-yl)propanenitriles was evaluated as a molecular starting point. Structure-activity relationships (SARs) revealed a ligand-efficient (LE) JAK inhibitor series, amenable to aqueous solubility. Subsequent in vitro analysis indicated the potential for off-target toxicity. A KINOMEscan selectivity profile of 5 substantiated the likelihood of widespread series affinity across the human kinome. An sp²-to-sp³ drug design strategy was undertaken to attenuate off-target kinase activity while driving JAK-STAT potency and aqueous solubility. Tactics to reduce aromatic character, increase fraction sp³ (Fsp³), and bolster molecular complexity led to the azetidin-3-amino bridging scaffold in 31.

Preclinical characterization of water-free cyclosporine eye drops - factors impacting ocular penetration ex vivo and in vivo

Although the efficacy of Cyclosporine A (CsA) in the management of ocular inflammation is well-demonstrated, ocular delivery remains challenging due to its hydrophobic nature. The semifluorinated alkane, perfluorobutylpentane (F4H5) has previously been suggested as an efficient vehicle for preparation of CsA eyedrops. Here we evaluated the influence of drop volume and the formulation aid, ethanol (EtOH), on ocular penetration of CsA and compared it to that of the commercial eyedrop, Ikervis, ex vivo and in vivo. Moreover, conjunctival and corneal tolerability after EtOH addition were evaluated ex vivo. The F4H5/EtOH vehicle was well tolerated and resulted in better corneal CsA penetration (AUC_{(0 - 4h)}: 63,008 ± 3,946 ng.h.g^-1) than Ikervis (AUC_{(0 - 4h)}: 10,328 ± 1,462 ng.h.g^-1) or F4H5 alone (AUC_{(0 - 4h)}: 50,734 ± 3,472 ng.h.g^-1) ex vivo. Interestingly, in vivo the CsA concentration in cornea, conjunctiva and lacrimal glands observed after administration of the F4H5 formulation (AUC_{(0.133-24 h)}: 7,741 ± 1,334 ng.h.g^-1, 1,313 ± 291 ng.h.g^-1, 48.2 ± 26.3 ng.h.g^-1) and F4H5/EtOH both at a reduced dose of 11 µl (AUC_{(0.133-24 h)}: 9,552 ± 1,738 ng.h.g^-1, 1,679 ± 285 ng.h.g^-1, 50.3 ± 21.1 ng.h.g^-1) was similar or even greater than what was observed on administration of 50 µl Ikervis (AUC_{(0.133-24 h)}: 9,943 ± 1,413 ng.h.g^-1, 2,069 ± 263 ng.h.g^-1, 30.6 ± 18.4 ng.h.g^-1). Thus, F4H5-based eyedrops were shown to deliver CsA more efficiently to anterior ocular tissues at a reduced dose in comparison to Ikervis, reducing dose wastage and minimizing any potential systemic side effects.

Increased activity of lacrimal gland mast cells are associated with corneal epitheliopathy in aged mice

The lacrimal gland undergoes significant structural and functional deterioration with aging. Marked with increased inflammation and fibrosis, the aged lacrimal gland is unable to perform its protective function. As a result, the ocular surface becomes highly susceptible to various ocular surface pathologies, including corneal epitheliopathy. We and others have previously shown that mast cells mediate tissue inflammation by recruiting other immune cells. However, despite their well-known characteristics of secreting various inflammatory mediators, whether mast cells contribute to the immune cell aggregation and activation, and acinar dystrophy of the aged lacrimal gland has not been investigated. Here, we demonstrate the role of mast cells in age-related lacrimal gland pathophysiology using mast cell-deficient (cKitw-sh) mice. Our data demonstrated a significant increase in mast cell frequencies and immune cell infiltration in the lacrimal gland of aged mice. Interestingly, mast cell deficiency resulted in a substantial reduction in inflammation and preservation of lacrimal gland structure, suggesting that mast cells mediate the aging process of the lacrimal gland.

Solving STODS-Surgical Temporary Ocular Discomfort Syndrome

The term STODS (Surgical Temporary Ocular Discomfort Syndrome) has been coined to describe the ocular surface perturbations induced by surgery. As one of the most important refractive elements of the eye, Guided Ocular Surface and Lid Disease (GOLD) optimization is fundamental to success in achieving refractive outcomes and mitigating STODS. Effective GOLD optimization and the prevention/treatment of STODS requires an understanding of the molecular, cellular, and anatomic factors that influence ocular surface microenvironment and the associated perturbations induced by surgical intervention. By reviewing the current understanding of STODS etiologies, we will attempt to outline a rationale for a tailored GOLD optimization depending on the ocular surgical insult. With a bench-to-bedside approach, we will highlight clinical examples of effective GOLD perioperative optimization that can mitigate STODS' deleterious effect on preoperative imaging and postoperative healing.

A randomized multicenter evaluation of the efficacy of 0.15% hyaluronic acid versus 0.05% cyclosporine A in dry eye syndrome

Hyaluronic acid (HA) and cyclosporine A (CsA) eyedrops are commonly prescribed in dry eye syndrome (DES). The effectiveness of each preparation in DES is well-known, yet the superiority of one over another has been studied little. We assessed the efficacy and tolerability of 0.15% HA compared to combinations of 0.05% CsA plus 0.5% carboxymethylcellulose (CMC), and 0.15% HA plus 0.05% CsA in patients with moderate to severe DES. Total 438 patients with moderate to severe DES were recruited and randomized for one of the three treatments for 12 weeks. Effectiveness was assessed at baseline, 4- and 12-weeks. The primary endpoint was change in corneal staining score. The secondary endpoints were tear break-up time (TBUT), strip meniscometry (SM) score, ocular surface disease index (OSDI) score, and tolerability questionnaire. The change in corneal staining score for 0.15% HA from the baseline was non-inferior to that of 0.05% CsA. Corneal staining score, TBUT, SM score, and OSDI score improved in all groups without statistically significant intergroup differences. Better tolerability and lower prevalence of adverse drug reactions were seen in 0.15% HA. Our findings suggest that 0.15% HA may be equivalently effective and safer than 0.05% CsA in treating moderate to severe DES.

Tear instability in the fellow eye of unilateral nasolacrimal obstruction and resolution with dacryocystorhinostomy

PURPOSE

To determine the effect of unilateral primary acquired nasolacrimal obstruction (PANDO) on ocular surface parameters in PANDOeyes and fellow eyes and changes in these parameters after dacryocystorhinostomy.

METHODS

Tear osmolarity, tear break-up time (TBUT), Schirmer's test, Meibomian gland score, and Lissamine Green staining of PANDO eyes and fellow eyes were measured preoperatively and postoperatively at Day 15, 1 month, and 3 months. Lacrimal irrigation and epiphora symptomatology were evaluated at all follow-up visits, and patients who did not meet surgical success criteria were excluded from the study.

RESULTS

Twenty-nine patients who underwent successful dacryocystorhinostomy surgery were included in the study. Preoperative and postoperative Day 15 Schirmer (p = .019, p = .001) and TBUT (p = .039, p = .043) were significantly lower in the fellow eye compared to PANDO eyes. The differences observed between PANDO eyes and fellow eyes in all other parameters were not significant (p > .05). Preoperatively PANDO eye parameters were normal, whereas TBUT (7.59 ± 5.39 s) and tear osmolarity (308.59 ± 17.32 mOsm/L) values of the fellow eye may be indicative of tear film instability. TBUT and tear osmolarity of the fellow eye showed significant improvement 3 months postoperatively compared to preoperative values (p = .010; p = .027 respectively).

CONCLUSION

Schirmer and TBUT values of the fellow eye were significantly lower than PANDO eyes preoperatively, one month after surgery there was no significant difference. TBUT and tear osmolarity of the fellow eyes may be indicative of tear instability preoperatively with improvement 3 months after dacryocystorhinostomy.

Reduced tear break-up time in the fellow eye of patients with unilateral primary acquired nasolacrimal duct obstruction

PURPOSE

To measure tear osmolarity, Schirmer I test and tear break-up time (TBUT) values in the obstructed and non-obstructed fellow eye of unilateral primary acquired nasolacrimal duct obstruction (PANDO) patients and compare them with healthy controls.

METHODS

In this prospective noninterventional study, the tear osmolarity, Schirmer I test, and TBUT values from unilateral PANDO eyes, fellow eyes, and control eyes of all subjects were measured.

RESULTS

The study included 114 eyes of 30 PANDO patients as well as 27 healthy controls. There was a significant difference between TBUT and Schirmer values of fellow eyes and PANDO eyes (p = 0,035; p = 0,001). There was no significant difference in any of the ocular surface parameters between PANDO eyes and control eyes (p > 0.05). When fellow eyes were compared to control eyes, there was a significant difference in TBUT (p = 0.046).

CONCLUSIONS

Decreased TBUT was exhibited by the fellow eye of unilateral PANDO patients, compared to the PANDO side and controls. Compensatory changes in PANDO eyes due to a decrease in the tear secretion reflex may lead to tear dysfunction of the fellow eye. Clinicians should assess tear stability in the fellow eye of PANDO patients as this could be leading to added symptomatic complaints.

Corneal subbasal nerve analysis in patients with primary Sjogren's syndrome: a novel objective grading method and clinical correlations

PURPOSE

To investigate corneal sub-basal nerve morphology changes in primary Sjogren's syndrome (SS) dry eye (SSDE) patients and determine the association with disease severity at microstructural level.

METHODS

Twenty-eight eyes of 17 SSDE and 82 eyes of 47 age- and sex-matched non-SS dry eye (NSSDE) patients were included. The Ocular Surface Disease Index questionnaire (OSDI), Schirmer's test (ST), tear meniscus height (TMH), non-invasive breakup time (NIBUT), meibomian gland (MG) morphology, and ocular staining score (OSS) were assessed. In vivo confocal microscopy was performed to observe corneal sub-basal nerve morphology (length, reflectivity, width, and tortuosity). Associations between clinical features and nerve parameters were analysed.

RESULTS

SSDE patients more frequently had increased nerve reflectivity (151.12 ± 17.07 vs. 139.37 ± 14.31 grey value), width (4.45 ± 0.87 vs. 3.92 ± 0.81 μm), tortuosity (132.90 ± 8.04 vs. 129.50 ± 7.33 degree), and higher reflectivity, width, and total nerve grades than NSSDE individuals (all P < 0.05). Significant associations were found between nerve reflectivity/width and anti-SSA [OR = 1.139 (1.013-1.281)/1.802 (1.013-4.465)]/labial gland biopsy [OR = 1.046 (1.002-1.161)/1.616 (1.020-3.243)]. Higher nerve width was associated with increased OSDI [β = 0.284 (0.187-0.455)], MG score [β = 0.185 (0.109-0.300)] and OSS [β = 0.163 (0.020-0.345)], but decreased NIBUT [β =  - 0.247 (- 0.548 ~  - 0.154)]. Higher nerve total grade was associated with increased OSDI [β = 0.418 (0.157-0.793)] and OSS [β = 0.287 (0.027-0.547)], but decreased ST [β =  - 0.410 (-0.857 ~  - 0.138)].

CONCLUSIONS

Corneal nerve morphology changes associated with clinical features in SS patients. These changes may facilitate severity evaluation and management of the disease.

Tear and ocular surface disease biomarkers: A diagnostic and clinical perspective for ocular allergies and dry eye disease

Validated biomarkers to be used as biological tools for managing ocular surface diseases (OSDs) are still an unmet need in daily clinical practice. Many studies have contributed to the already extensive list of candidate biomarkers for these disorders. Dry eye (DE) and ocular allergy (OA) are complex and multifactorial diseases, often coexisting and with overlapping symptoms. The purpose of this review is to present a comprehensive updated revision of the most relevant biomarkers of DE and OA, with an emphasis on quantitative analyses and correlations with clinical parameter data. Analysis of biomarkers common for these pathologies has highlighted an important physiological process. Namely, the interleukin proteins (IL-1α, IL-1β and IL-17), tumour necrotic factor (TNFα) and interferon gamma (IFNγ; Th1-Th7 pathway) and IL-4, IL-5 and IL-13 (Th2 pathway) seem to represent similar inflammatory mechanisms. Moreover, changes in the levels of mucins (MUC1, MUC2, MUC4, MUC5 and MUC16) are common alterations in the tear film mucous layer. We also examine the current state of medical devices and the main limitations to their use in clinical practice. Translational research in biomarkers for clinical practice depends on a feasible transition from the laboratory to the point-of-care. This requires large-scale, coordinated clinical validation campaigns to select the biomarkers with the highest specificity and sensitivity and significant correlation with clinical parameters. Moreover, technical limitations of multiplexed quantitation systems must be overcome to detect and measure the levels of several biomarkers in very small samples. To ensure the future of biomarker research, significant progress is necessary in a number of fields. There is an urgent need for global unification of clinical classification and diagnostics criteria. Widespread integration of proteomic and transcriptomic data is paramount for performing meaningful analyses using appropriate bioinformatics tools and artificial intelligence systems.

Current trends in pharmaceutical treatment of Dry Eye Disease: A review

Dry eye disease (DED), keratoconjunctivitis sicca or dysfunctional tear syndrome, is the most prevalent ophthalmic disease which affects a substantial segment of people worldwide with increasing frequency. It is considered a multifactorial disease of the ocular surface and tear film, characterized by a variation of signs and symptoms. The symptoms range from mild to severe itching, burning, irritation, eye fatigue, and ocular inflammation that may lead to potential damage to the cornea, conjunctiva and even vision loss. Correspondingly, depending on the different manifestations and pathophysiology, the treatment must be tailored specifically to each patient by targeting the specific mechanisms implicated in their disease. Currently, there are several medical products and techniques available or under investigation for the treatment of DED. The present article focused on the pathophysiology of DED, the new diagnostic approach and the recently developed drug delivery systems or devices reducing the progress of the disease and treating the causes.

Nicotinic acetylcholine receptor stimulation: A new approach for stimulating tear secretion in dry eye disease

Tear secretion is regulated by the lacrimal functional unit consisting of afferent and efferent nerve innervation. The afferent arm consists of trigeminal nociceptors on the ocular surface and nasal mucosa. When stimulated by agonists, nicotinic acetylcholine receptors on nerve endings in the nose initiate a reflex arc resulting in instantaneous tear secretion. Pharmacologic nasal neural stimulation to increase endogenous tear production is a novel approach to treating dry eye disease.

Evaluation of ocular surface parameters in dogs with and without meibomian gland dysfunction

BACKGROUND

Interest in meibomian gland dysfunction (MGD) is growing in veterinary medicine. However, research on MGD in dogs is lacking. The aims of this study were to compare the interferometry grades, tear meniscus height (TMH) and non-invasive tear break-up time (NIBUT) grades between dogs with and without MGD.

METHODS

Routine ophthalmic examination, interferometry, NIBUT assessment, TMH measurement and meibography were performed. Age and Schirmer tear test-1 (STT-1) results were compared between the control and MGD groups using Student's t-test. Interferometry grades, NIBUT grades and TMH were compared between the two groups using Mann-Whitney U-test.

RESULTS

There was no significant difference in age between the two groups (p = 0.279). STT-1 (p = 0.024), interferometry (p = 0.004) and NIBUT grades (p = 0.012) were significantly lower in the MGD group than in the control group. No significant difference in TMH values (p = 0.587) was observed between the two groups. While the control group included 18 and seven eyes in meiboscore 0 and 1, in MGD group, 12, eight, five and three eyes were included in meiboscore 0, 1, 2 and 3, respectively.

CONCLUSIONS

Low interferometry and NIBUT grades were associated with MGD, suggesting decreased meibum and disrupted tear film quality. TMH did not differ between the two groups. Meibography could aid in the diagnosis of MGD in severe cases, although it could not detect early MGD in the dogs in this study.

IL-17 Producing Lymphocytes Cause Dry Eye and Corneal Disease With Aging in RXRα Mutant Mouse

Purpose

To investigate IL-17 related mechanisms for developing dry eye disease in the Pinkie mouse strain with a loss of function RXRα mutation.

Methods

Measures of dry eye disease were assessed in the cornea and conjunctiva. Expression profiling was performed by single-cell RNA sequencing (scRNA-seq) to compare gene expression in conjunctival immune cells. Conjunctival immune cells were immunophenotyped by flow cytometry and confocal microscopy. The activity of RXRα ligand 9-cis retinoic acid (RA) was evaluated in cultured monocytes and γδ T cells.

Results

Compared to wild type (WT) C57BL/6, Pinkie has increased signs of dry eye disease, including decreased tear volume, corneal barrier disruption, corneal/conjunctival cornification and goblet cell loss, and corneal vascularization, opacification, and ulceration with aging. ScRNA-seq of conjunctival immune cells identified γδ T cells as the predominant IL-17 expressing population in both strains and there is a 4-fold increased percentage of γδ T cells in Pinkie. Compared to WT, IL-17a, and IL-17f significantly increased in Pinkie with conventional T cells and γδ T cells as the major producers. Flow cytometry revealed an increased number of IL-17⁺ γδ T cells in Pinkie. Tear concentration of the IL-17 inducer IL-23 is significantly higher in Pinkie. 9-cis RA treatment suppresses stimulated IL-17 production by γδ T and stimulatory activity of monocyte supernatant on γδ T cell IL-17 production. Compared to WT bone marrow chimeras, Pinkie chimeras have increased IL-17⁺ γδ T cells in the conjunctiva after desiccating stress and anti-IL-17 treatment suppresses dry eye induced corneal MMP-9 production/activity and conjunctival goblet cell loss.

Conclusion

These findings indicate that RXRα suppresses generation of dry eye disease-inducing IL-17 producing lymphocytes s in the conjunctiva and identifies RXRα as a potential therapeutic target in dry eye.

Effect of low-level light therapy in patients with dry eye: a prospective, randomized, observer-masked trial

To evaluate the efficacy of low-level light therapy (LLLT) with near-infrared light-emitting diodes (LED-LLLT) for the treatment of dry eye. 40 patients were randomly assigned with a 1:1 allocation ratio to receive LED-LLLT (LLLT group, n = 20) or placebo treatment (placebo group, n = 20). Patients in the LLLT group received LLLT twice a week for 3 weeks, for a total of 6 treatment sessions. The primary endpoint was the changes in the fluorescein corneal staining (FCS) score. The secondary endpoints were the changes in the ocular surface disease index (OSDI) score, lissamine green conjunctival staining (LGCS) scores, tear film break-up time (TBUT), Schirmer test, and the meibomian gland dysfunction (MGD) index. These were evaluated before treatment and 4 weeks after start of treatment. The mean difference of score change in primary endpoint revealed significant improvement in the LLLT group, compared to the placebo. Among secondary endpoints, LGCS, Schirmer's test, upper meibography scores showed significant improvements, while TBUT, lid debris, lid swelling, lid telangiectasia, meibomian gland secretion and expressibility scores had slight improvement without significant differences. No serious adverse events were observed. The use of LED-LLLT for the treatment of dry eye and MGD appears to be safe and beneficial.