Dry eye syndrome: comprehensive etiologies and recent clinical trials

Dry eye disease caused by viral infection: Past, present and future

Following viral infection, the innate immune system senses viral products, such as viral nucleic acids, to activate innate defence pathways, leading to inflammation and apoptosis, control of cell proliferation, and consequently, threat to the whole body. The ocular surface is exposed to the external environment and extremely vulnerable to viral infection. Several studies have revealed that viral infection can induce inflammation of the ocular surface and reduce tear secretion of the lacrimal gland (LG), consequently triggering ocular morphological and functional changes and resulting in dry eye disease (DED). Understanding the mechanisms of DED caused by viral infection and its potential therapeutic strategies are crucial for clinical interventional advances in DED. This review summarizes the roles of viral infection in the pathogenesis of DED, applicable diagnostic and therapeutic strategies, and potential regions of future studies.

Gender-Related Differences in Dry Eye Symptoms Following Involutional Ectropion and Entropion Surgery

This prospective case-control study investigated gender-related differences in dry eye symptoms following surgery for involutional ectropion and entropion. A total of 109 patients, aged between 65 and 89, were categorized by eyelid condition and gender. Postoperative assessments included the Tear Film Break-Up Time (TBUT) test, Schirmer I test results, corneal and conjunctival staining, eyelid margin characteristics, and scores from the Ocular Surface Disease Index (OSDI) questionnaire. The analysis revealed notable gender-related differences in dry eye manifestations. Initially, men exhibited lower TBUT scores but higher Schirmer test readings compared to women; however, these disparities diminished over time. No significant gender differences were detected in corneal and conjunctival staining, indicating similar levels of ocular surface damage across genders. Males showed significantly higher values in several eyelid margin characteristics (LMI, LMT) at various postoperative time points. According to the OSDI questionnaire, women experienced more severe symptoms of dry eye both pre- and post-operatively, suggesting a greater subjective symptom burden. When comparing surgical outcomes for ectropion and entropion, both conditions showed improvement in eyelid positioning and dry eye symptoms post-surgery. Despite these improvements, women with either condition reported more severe dry eye symptoms compared to men throughout the postoperative period. This study highlights the gender-specific variations in dry eye symptoms following eyelid malformation surgery and emphasizes the importance of adopting gender-sensitive approaches in postoperative care to improve outcomes and ocular health.

The level of cytokines in tears as a novel indicator of demyelinating diseases

INTRODUCTION

A novel research objective is to identify new molecules in more readily accessible biological fluids that could be used in the diagnosis of multiple sclerosis (MS) and other demyelinating disorders.

AIM

To compare the level of selected cytokines in tears between patients with MS or other demyelinating disorder and healthy controls.

MATERIAL AND METHODS

84 patients with diagnosed MS during remission or with other demyelinating disease of the CNS and 70 healthy controls were enrolled in the study. Tears were collected without any stimulation and stored till the day of assessment. The concentration of selected cytokines was measured by the Bio-Plex Pro Human cytokine screening panel 27 cytokines assay according to the manufacturer's instructions. Statistical analysis was performed with Statistica 13.

RESULTS

IL-1b level was significantly lower in the study group compared to the control group [3,6 vs 8.71, p < 0.001]. The same pattern was observed for IL-6 [3,1 vs 5.26, p = 0.027] and IL-10 [1,7 vs 10.92, p < 0.001] (Table 1). In the study group, IL-1RA (p = 0.015), IL-5 (p = 0.04), IL-9 (p = 0.014), and IL-15 (p = 0.037) showed significant correlations with age. In the total sample, IL-1Ra (p = 0.016) and IFN-g (p = 0.041) were significantly correlated with age, while in the control group, IL-8 (p = 0.09), MIP-1a (p = 0.009), and RANTES (p = 0.031) showed significant correlations.

CONCLUSIONS

Our results show that MS and other demyelination diseases lead to decrease in the overall level of cytokines in tears. Further research is needed to determine the role of tear fluid in the assessment of demyelinating disorders like MS.

Post-refractive Surgery Dry Eye: A Systematic Review Exploring Pathophysiology, Risk Factors, and Novel Management Strategies

Dry eye disease frequently manifests following corneal refractive procedures, significantly impacting patients' quality of life. This review systematically synthesizes current evidence on the pathophysiological mechanisms, risk factors, and therapeutic interventions for post-refractive surgery dry eye. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, a systematic review of literature published until August 2023 was conducted, focusing on post-refractive surgery dry eye. Eighteen relevant studies were identified through screening and eligibility assessment. A qualitative synthesis of outcomes was performed using narrative and thematic analysis methods. Surgically induced neurotrophic deficiency, stemming from nerve transection, triggers a cascade of events including apoptosis, inflammation, and lacrimal dysfunction, ultimately leading to tear film instability. Risk factors such as female gender, thyroid eye disease, meibomian gland dysfunction, higher ablation depths, and the use of LASIK over surface ablation exacerbate the condition. While conventional treatments like artificial tears provide temporary relief, emerging interventions such as nerve growth factors, matrix metalloproteinase inhibitors, serum eye drops, and specialized contact lenses show promise in promoting nerve regeneration and epithelial healing. Strategies such as customized ablation profiles, smaller optical zones, and nerve-sparing techniques like small incision lenticule extraction demonstrate potential advantages. A multifaceted therapeutic approach targeting neuroprotection, anti-inflammatory mechanisms, and tear film stabilization is imperative for effectively managing post-refractive surgery dry eye. Future research should focus on evaluating prognostic biomarkers, exploring precision medicine approaches, and investigating neuroprotective adjuvants to further enhance treatment outcomes.

Silk Fibroin Formed Bioadhesive Ophthalmic Gel for Dry Eye Syndrome Treatment

PURPOSE

Dry eye syndrome (DES), arising from various etiologic factors, leads to tear film instability and ocular surface damage. Given its anti-inflammatory effects, cyclosporine A (CsA) has been widely used as a short-term treatment option for DES. However, poor bioavailability and solubility of CsA in aqueous phase make the development of a cyclosporine A-based eye drop for ocular topical application a huge challenge.

METHODS

In this study, a novel strategy for preparing cyclosporine A-loaded silk fibroin nanoemulsion gel (CsA NBGs) was proposed to address these barriers. Additionally, the rheological properties, ocular irritation potential, tear elimination kinetics, and pharmacodynamics based on a rabbit dry eye model were investigated for the prepared CsA NBGs. Furthermore, the transcorneal mechanism across the ocular barrier was also investigated.

RESULTS

The pharmacodynamics and pharmacokinetics of CsA NBGs exhibited superior performance compared to cyclosporine eye drops, leading to a significant enhancement in the bioavailability of CsA NBGs. Furthermore, our investigation into the transcorneal mechanism of CsA NBGs revealed their ability to be absorbed by corneal epithelial cells via the paracellular pathway.

CONCLUSION

The CsA NBG formulation exhibits promising potential for intraocular drug delivery, enabling safe, effective, and controlled administration of hydrophobic drugs into the eye. Moreover, it enhances drug retention within the ocular tissues and improves systemic bioavailability, thereby demonstrating significant clinical translational prospects.

Role of NADPH Oxidase 4 on Dry Eye Syndrome in Mice

Objective: This study aims to investigate the effect of NADPH oxidase 4 (NOX4)-mediated inflammation on concanavalin A (ConA)-induced dry eye syndrome (DES) in mice. Methods: Thirty-six mice were randomly divided into Control, Model, no-load Control, and NOX4 interference group. Adenovirus was injected (10 μL) into the lacrimal glands of both eyes of mice in no-load Control group and NOX4 interference group. Four days after adenovirus injection, the Control group was injected with phosphate-buffered saline, and the other groups were injected with ConA (200 μg) in the lacrimal glands of mice to establish DES models. The tear secretion rate was estimated by phenol red thread test. Lissamine green eye staining was used to evaluate conjunctival damage. The corneal surface was observed by hematoxylin-eosin (HE) staining and scanning electron microscopy (SEM). The morphology and quantity of conjunctival epithelial cells and goblet cells were observed by Periodic acid-Schiff staining. The expression of NOX4, NOD-like receptor thermal protein domain-associated protein 3 (NLRP3), interleukin-1β (IL-1β), and mucin 5 subtype AC (MUC5AC) was detected by immunohistochemistry. Results: Compared with the Control group, the Model group showed a significant decrease in tear secretion and an upregulation in microscopic image score. The HE staining and SEM showed corneal and conjunctiva damage in the Model group. The protein expression of NOX4, NLRP3, and IL-1β was upregulated, but MUC5AC was downregulated in the Model group. After interfering with NOX4, all these indicators were reversed. Conclusion: The pathological process of concanavalin A-induced DES appears to be related to NOX4.

A novel multi-ingredient supplement significantly improves ocular symptom severity and tear production in patients with dry eye disease: results from a randomized, placebo-controlled clinical trial

Introduction

Dry eye disease (DED) is multifactorial and characterized by a loss of tear film homeostasis that causes a cycle of tear film instability, tear hyperosmolarity, and inflammation. While artificial tears are the traditional mainstay of treatment, addressing the underlying pathophysiology could relieve symptoms and prevent progression. Increasing evidence indicates a role for oral nutritional supplementation in multiple ophthalmic diseases, including DED. Lutein, zeaxanthin, curcumin, and vitamin D3 have demonstrated protective and anti-inflammatory properties in ocular models. This prospective, randomized, double-blind, parallel, placebo-controlled study evaluated the efficacy and safety of a proprietary blend of lutein, zeaxanthin isomers, curcumin, and vitamin D3 (LCD) as a daily supplement in adult participants with DED.

Methods

Participants were randomized to receive one LCD supplement capsule (lutein 20 mg, zeaxanthin isomers 4 mg, curcumin 200 mg curcuminoids, and vitamin D3 600 IU) or placebo per day for 8 weeks (LCD, n=77; placebo, n=78). Primary outcomes were changes in tear volume (Schirmer's test) and ocular symptoms (Ocular Surface Disease Index [OSDI]).

Results

The study met its primary endpoints: the LCD group demonstrated significantly better Schirmer's test scores and improvement in overall OSDI score, versus placebo, at Day 56 (p<0.001 for both). Scores for total OSDI, and symptoms and vision domains, significantly improved by Day 14 for LCD versus placebo, (p<0.05 for all) and were maintained to Day 56 (p<0.001). In addition, the LCD group demonstrated significantly improved tear film break-up time (TBUT) and tear film osmolarity, versus placebo, by Day 56 (p<0.001), along with significant improvements in corneal and conjunctival staining (p<0.001 for both), and inflammation (matrix metalloproteinase-9; p<0.001 for each eye). Total Standard Patient Evaluation of Eye Dryness (SPEED) score, and scores for the frequency and severity domains, were significantly improved by Day 14 for LCD versus placebo (p<0.05 for all) and maintained to Day 56 (p<0.001). There was no difference between groups for artificial tear usage. The supplement was well-tolerated.

Discussion

Once-daily LCD supplementation significantly improved tear production, stability and quality, reduced ocular surface damage and inflammation, and improved participants' symptoms. LCD supplementation could offer a useful adjunct to artificial tears for patients with DED (NCT05481450).

Mucoadhesive liposomal delivery system synergizing anti-inflammation and anti-oxidation for enhanced treatment against dry eye disease

Dry eye disease (DED) is a common and frequent ocular surface disease worldwide, which can cause severe ocular surface discomfort and blurred vision. Inflammation and reactive oxygen species (ROS) play decisive roles in the development of DED. However, existing treatments usually focus on anti-inflammation while ignore the role of ROS in DED. Ever worse, the clinical preparations are easily cleared by nasolacrimal ducts, resulting in poor therapeutic effect. To circumvent these obstacles, here we designed a phenylboronic acid (PBA) modified liposome co-loading immunosuppressant cyclosporin A (CsA) and antioxidant crocin (Cro). The CsA/Cro PBA Lip achieved mucoadhesion through the formation of covalent bonds between PBA and the sialic acid residues on mucin, and consequently improved the retention of drugs on the ocular surface. By inhibiting ROS production and blocking NF-κB inflammatory pathway, CsA/Cro PBA Lip successfully promoted the healing of damaged corneal epithelium, eventually achieving the goal of relieving DED. CsA/Cro PBA Lip is proven a simple yet effective dual-drug delivery system, exhibiting superior antioxidant and anti-inflammatory effects both in vitro and in vivo. This approach holds great potential in the clinical treatment of DED and other related mucosal inflammations.

Potential New Target for Dry Eye Disease-Oxidative Stress

Dry eye disease (DED) is a multifactorial condition affecting the ocular surface. It is characterized by loss of tear film homeostasis and accompanied by ocular symptoms that may potentially result in damage to the ocular surface and even vision loss. Unmodifiable risk factors for DED mainly include aging, hormonal changes, and lifestyle issues such as reduced sleep duration, increased screen exposure, smoking, and ethanol consumption. As its prevalence continues to rise, DED has garnered considerable attention, prompting the exploration of potential new therapeutic targets. Recent studies have found that when the production of ROS exceeds the capacity of the antioxidant defense system on the ocular surface, oxidative stress ensues, leading to cellular apoptosis and further oxidative damage. These events can exacerbate inflammation and cellular stress responses, further increasing ROS levels and promoting a vicious cycle of oxidative stress in DED. Therefore, given the central role of reactive oxygen species in the vicious cycle of inflammation in DED, strategies involving antioxidants have emerged as a novel approach for its treatment. This review aims to enhance our understanding of the intricate relationship between oxidative stress and DED, thereby providing directions to explore innovative therapeutic approaches for this complex ocular disorder.

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.

A combined treatment for patients with dry eye and associated laryngopharyngeal reflux: a real-life approach

AIM

To evaluate the efficacy and tolerability of administering a combined therapy in patients with dry eye syndrome (DES) and associated laryngopharyngeal reflux (LPR).

METHODS

The study was retrospective, open, observational, and conducted in a real-life setting. Patients had pathological symptom assessment in dry eye (SANDE) and reflux symptom index (RSI) at baseline. Patients were re-assessed after 1mo and at the end of treatment. The treatment consisted of a three-month course based on the combined therapy: Gastroftal eye drops, one drop three times a day, and Gastroftal tablets, two tablets after lunch and two tablets after dinner. Tear break-up-time (TBUT) test, Schirmer test, RSI, and SANDE questionnaire were evaluated.

RESULTS

The study included 253 patients. The mean age was 58±11.19y. TBUT test score and Schirmer's test significantly increased (both P<0.001) after 1mo and at the end of treatment. The RSI score and SANDE scores significantly decreased (both P<0.001) after 1mo and at the end of treatment.

CONCLUSION

The current, retrospective, and open study shows that combined therapy using Gastroftal eye drops and tablets could represent a valuable option in managing patients with DES associated with LPR.

Evaluating the Efficacy of Polyglycolic Acid-Loading Tetrandrine Nanoparticles in the Treatment of Dry Eye

INTRODUCTION

Dry eye disease (DED) is a multifactor-induced disease accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. Traditional anti-inflammation agent corticosteroids applied in DED treatment could result in high intraocular pressure, especially in long-term treatment. Therefore, we explored a nano drug that aimed to block the formation pathway of DED which had anti-inflammatory, sustained release, and good biocompatibility characteristics in this study.

METHODS

We prepared a novel nanomedicine (Tet-ATS@PLGA) by the thin film dispersion-hydration ultrasonic method and detected its nanostructure, particle size, and zeta potential. Flow cytometry was used to detect the cell survival rate of each group after 24 h of drug treatment on inflammed Statens Seruminstitut Rabbit Corneal (SIRC) cells. Observed and recorded corneal epithelial staining, tear film rupture time, and Schirmer test to detect tear secretion on the ocular surface of rabbits. The corneal epithelial thickness, morphology, and number of bulbar conjunctival goblet cells were recorded by H&E staining. Finally, we detected the expression of VEGF, IL-1β, PGE2, and TNF-α by cellular immunofluorescence staining and enzyme-linked immunosorbent assay (ELISA).

RESULTS

The encapsulation efficiency and drug loading of Tet-ATS@PLGA were 79.85% and 32.47%, respectively. At eye surface temperature, Tet can easily release from Tet-ATS@PLGA while that it was difficult to release at storage temperature and room temperature. After 2 weeks medication, Tet-ATS@PLGA can effectively improve the tear film rupture time and tear secretion time in a DED model (p <0.05). Compared with the normal group (62.34 ± 4.86 mm), the thickness of corneal epithelium in ATS (29.47 ± 3.21 mm), Tet-ATS (46.23 ± 2.87 mm), and Tet-ATS@PLGA (55.76 ± 3.95 mm) gradually increased. Furthermore, the flow cytometry indicated that Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory SIRC cells, and the cellular immunofluorescence and ELISA experiments showed that the expression intensity of inflammatory factors such as VEGF, IL-1β, PGE2, and TNF-α decreased in this process. Interestingly, Tet also had the effect of reducing intraocular pressure.

CONCLUSION

Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory corneal epithelial cells, thus inhibiting the expression of inflammatory factors to block the formation of DED and improve the secretion of tear on the ocular surface.

Does Menopausal Status Affect Dry Eye Disease Treatment Outcomes with OC-01 (Varenicline Solution) Nasal Spray? A Post Hoc Analysis of ONSET-1 and ONSET-2 Clinical Trials

INTRODUCTION

This study sought to compare the efficacy of OC-01 (varenicline solution) nasal spray for treatment of dry eye disease (DED) in postmenopausal women (PM+) versus women who were not postmenopausal (PM-).

METHODS

This was a post hoc subgroup analysis of data integrated from two prior randomized controlled clinical trials, ONSET-1 and ONSET-2. Women randomized to treatment with OC-01 (varenicline solution) nasal spray 0.03 mg or vehicle control (VC) whose self-reported menopausal status (PM+ versus PM-) was known were included. Outcomes included the treatment difference (the OC-01 [varenicline solution] nasal spray change from baseline [CFB] minus VC CFB) in Schirmer test score (STS, mm) with anesthesia and the eye dryness score (EDS) measured on a 100-mm visual analog scale (0 = no discomfort, 100 = maximal discomfort). Least-squares mean treatment differences were derived from analysis of covariance (ANCOVA) models.

RESULTS

Overall, 449 female participants in the ONSET-1 and ONSET-2 trials randomized to the OC-01 (varenicline solution) nasal spray 0.03 mg or VC groups were included in this analysis. The treatment-menopausal status interaction terms in the STS and EDS ANCOVA and logistic regression models were not statistically significant (p > 0.05), indicating consistency of treatment effect between the PM- and PM+ groups. The treatment difference in STS was similar in the PM- and PM+ groups (6.7 and 5.5 mm, respectively). The treatment difference in EDS was similar in the PM- and PM+ groups (- 5.5 and - 4.1, respectively).

CONCLUSIONS

OC-01 (varenicline solution) nasal spray demonstrated similar efficacy in promoting natural tear production and improving symptoms in both PM- and PM+ groups. As menopausal-related hormonal changes may be associated with more severe DED, these results may support OC-01 (varenicline solution) nasal spray as an effective treatment for DED in women regardless of presenting menopausal status.

TRIAL REGISTRATION

Post hoc subgroup analysis of data integrated from ONSET-1 (ClinicalTrials.gov identifier NCT03636061) and ONSET-2 (ClinicalTrials.gov identifier NCT04036292).

Ocular Surface Ion Transport and Dry Eye Disease

Purpose of Review

To review the role of ocular surface epithelial (corneal and conjunctival) ion transporters in the pathogenesis and treatment of dry eye disease (DED).

Recent Findings

Currently, anti-inflammatory agents are the mainstay of DED treatment, though there are several agents in development that target ion transport proteins on the ocular surface, acting by pro-secretory or anti-absorptive mechanisms to increase the tear fluid Film volume. Activation or inhibition of selected ion transporters can alter tear fluid osmolality, driving water transport onto the ocular surface via osmosis. Several ion transporters have been proposed as potential therapeutic targets for DED, including the cystic fibrosis transmembrane conductance regulator (CFTR), calcium-activated chloride channels (CaCCs), and the epithelial sodium channel (ENaC).

Summary

Ocular surface epithelial cell ion transporters are promising targets for pro-secretory and anti-absorptive therapies of DED.