Alternative therapies for dry eye disease

Integrative therapeutics for ocular surface disorders

PURPOSE OF REVIEW

Integrative medicine techniques are increasingly accepted into the treatment paradigm for many chronic disorders including eye disease. Over 71% of patients, including 67% of those with eye disorders, use some form of Integrative therapy. Physicians should be well versed in evidence-based therapies to know how to refer patients for the best complimentary care. We highlight the most effective integrative therapeutics from different complementary treatment paradigms to offer a framework for approaching therapy in patients with ocular surface disorders (OSDs).

RECENT FINDINGS

Lifestyle and behavioral modifications help a proportion of people with OSDs like dry eye disease and allergic conjunctivitis, which are interrelated disorders. Nutrition and supplementation can also play a role in addressing underlying inflammation and improving OSD symptoms. Acupuncture and traditional herbal medicine may also benefit some patients. New technologies offer innovative treatment pathways in the treatment of OSD but require referral to Ocular Surface Treatment Centers.

SUMMARY

Integrative treatment approach for OSD incorporates allopathic medicine, traditional remedies and lifestyle behavioral interventions, Ayurveda and herbal medicine, Nutritional Supplements, Homeopathy, Acupuncture and Chinese Medicine. New cutting-edge technologies offer breakthroughs in difficult to treat ocular surface cases. Collaboration between allergy or otolaryngology offices, complementary practitioners, as well as optometrists and ophthalmologists in Ocular Surface Treatment Centers can offer patients new avenues of treatment.

Neurostimulation as a technology countermeasure for dry eye syndrome in astronauts

Dry eye syndrome (DES) poses a significant challenge for astronauts during space missions, with reports indicating up to 30% of International Space Station (ISS) crew members. The microgravity environment of space alters fluid dynamics, affecting distribution of fluids on the surface of the eye as well as inducing cephalad fluid shifts that can alter tear drainage. Chronic and persistent DES not only impairs visual function, but also compromises the removal of debris, a heightened risk for corneal abrasions in the microgravity environment. Despite the availability of artificial tears on the ISS, the efficacy is challenged by altered fluid dynamics within the bottle and risks of contamination, thereby exacerbating the potential for corneal abrasions. In light of these challenges, there is a pressing need for innovative approaches to address DES in astronauts. Neurostimulation has emerged as a promising technology countermeasure for DES in spaceflight. By leveraging electrical signals to modulate neural function, neurostimulation offers a novel therapeutic avenue for managing DES symptoms. In this paper, we will explore the risk factors and current treatment modalities for DES, highlighting the limitations of existing approaches. Furthermore, we will delve into the novelty and potential of neurostimulation as a countermeasure for DES in future long-duration missions, including those to the Moon and Mars.

Melatonin alleviates high-fat-diet-induced dry eye by regulating macrophage polarization via IFT27 and lowering ERK/JNK phosphorylation

Dry eye disease is the most common ocular surface disease globally, requiring a more effective treatment. We observed that a high-fat diet induced macrophage polarization to M1 and further induced inflammation in the meibomian and lacrimal glands. A four-week treatment with melatonin (MLT) eye drops can regulate macrophage polarization and alleviate dry eye signs. To investigate the therapeutic effects and mechanisms of action of MLT on high-fat-diet-induced dry eye disease in mice, RAW 264.7 cells pretreated with LPS and/or MLT underwent digital RNA with the perturbation of genes sequencing (DRUG-seq). Results showed that IFT27 was up-regulated, and MAPK pathways were suppressed after MLT pre-treatment. ERK/JNK phosphorylation was reduced in meibomian glands of MLT-treated dry eye mice and increased in IFT27 knockdown RAW 264.7 cells. In summary, MLT regulated macrophage polarization via IFT27 and reduced ERK/JNK phosphorylation. These results support that MLT is a promising medication for dry eye disease.

Long-term high fructose intake reprograms the circadian transcriptome and disrupts homeostasis in mouse extra-orbital lacrimal glands

This study aims to explore the effects of long-term high fructose intake (LHFI) on the structure, functionality, and physiological homeostasis of mouse extra-orbital lacrimal glands (ELGs), a critical component of ocular health. Our findings reveal significant reprogramming of the circadian transcriptome in ELGs following LHFI, alongside the activation of specific inflammatory pathways, as well as metabolic and neural pathways. Notably, LHFI resulted in increased inflammatory infiltration, enhanced lipid deposition, and reduced nerve fiber density in ELGs compared to controls. Functional assessments indicated a marked reduction in lacrimal secretion following cholinergic stimulation in LHFI-treated mice, suggesting impaired gland function. Overall, our results suggest that LHFI disrupts lacrimal gland homeostasis, potentially leading to dry eye disease by altering its structure and secretory function. These insights underscore the profound impact of dietary choices on ocular health and highlight the need for strategies to mitigate these risks.

The Utilization of Topical Insulin for Ocular Surface Diseases: A Narrative Review

Various etiologies, including diabetic keratopathy (DK), dry eye disease (DED), and neurotrophic keratopathy (NK), can disrupt corneal homeostasis, exacerbating corneal epithelial defects. Topical insulin has emerged as a promising therapy for promoting corneal wound healing and addressing underlying pathologies. This review systematically evaluates the efficacy of topical insulin across different corneal disorders. A literature review was conducted across the PubMed, Google Scholar, and Scopus research databases. The search resulted in a total of 19 articles, consisting of clinical trials, retrospective studies, and case reports. In DK, topical insulin accelerates corneal wound healing post-vitreoretinal surgery with lower concentrations showing higher outcomes when compared to conventional therapy, possibly due to improved epithelial stem cell migration. In comparison, the dry-eye disease results are inconclusive regarding patient-reported outcomes and corneal staining. For NK, topical insulin accelerates corneal wound healing and restores corneal nerve sensation. Other persistent epithelial defect (PED) etiologies that have been treated with topical insulin are infection, immune-mediated, mechanical and chemical trauma, and chronic ocular surface alterations. Although individual mechanisms for the benefits of topical insulin for each of these etiologies have not been studied, the literature demonstrates that topical insulin is efficacious for PEDs regardless of etiology. Future clinical trials need to be conducted to further evaluate optimal dosing, duration, and use of topical insulin for the restoration of the corneal surface.

Novel treatments for dry eye syndrome

Dry eye syndrome (DES) is a prevalent and multifactorial disease that leads to a self-perpetuating cycle of inflammation and damage to the ocular surface. This results in symptoms such as redness, burning, and blurred vision, which can negatively affect a patient's quality of life. While treatments are available to manage DES, they only temporarily relieve symptoms. Furthermore, long-term use of certain medications can cause harm to the ocular surface. Therefore, there is a need for safer and effective treatments for DES. This review highlights the latest advancements in DES therapy, providing valuable insights into ongoing efforts to improve patient outcomes.

A Miniaturized Wireless Micropump Enabled by Confined Acoustic Streaming

Miniaturization of health care, biomedical, and chemical systems is highly desirable for developing point-of-care testing (POCT) technologies. In system miniaturization, micropumps represent one of the major bottlenecks due to their undesirable pumping performance at such small sizes. Here, we developed a microelectromechanical system fabricated acoustic micropump based on an ultrahigh-frequency bulk acoustic wave resonator. The concept of an inner-boundary-confined acoustic jet was introduced to facilitate unidirectional flow. Benefitting from the high resonant frequency and confined acoustic streaming, the micropump reaches 32.620 kPa/cm3 (pressure/size) and 11.800 ml/min∙cm3 (flow rate/size), showing a 2-order-of-magnitude improvement in the energy transduction efficiency compared with the existing acoustic micropumps. As a proof of concept, the micropump was constructed as a wearable and wirelessly powered integrated drug delivery system with a size of only 9×9×9 mm3 and a weight of 1.16 g. It was demonstrated for ocular disease treatment through animal experimentation and a human pilot test. With superior pumping performance, miniaturized pump size, ultralow power consumption, and complementary metal-oxide-semiconductor compatibility, we expect it to be readily applied to various POCT applications including clinical diagnosis, prognosis, and drug delivery systems.

Inflammation mechanism and anti-inflammatory therapy of dry eye

Dry eye is a widespread chronic inflammatory disease that causes fatigue, tingling, burning, and other symptoms. Dry eye is attributed to rheumatic diseases, diabetes, hormone disorders, and contact lenses, which activate inflammatory pathways: mitogen-activated protein kinases (MAPK) and nuclear factor-B (NF-κB), promote macrophage inflammatory cell and T cell activation, and inflammation factors. Clinicians use a combination of anti-inflammatory drugs to manage different symptoms of dry eye; some of these anti-inflammatory drugs are being developed. This review introduces the dry eye inflammation mechanisms and the involved inflammatory factors. We also elucidate the anti-inflammatory drug mechanism and the detection limits.

Aprepitant Restores Corneal Sensitivity and Reduces Pain in DED

Purpose

This study aims to assess the efficacy of two aprepitant formulations (X1 and X2), in a preclinical model of dry eye disease (DED) induced by benzalkonium chloride (BAK).

Methods

Two aprepitant formulations were tested on 7 to 8-week-old male mice for their efficacy. In vivo corneal fluorescein staining assessed epithelial damage as the primary end point on days 0, 3, 5, 7, 9, 12, and 14 using slit-lamp microscopy. The DED model was induced with 0.2% BAK twice daily for the first week and once daily for the next week. Mice were randomly assigned to 5 treatment groups: Aprepitant X1 (n = 10) and X2 (n = 10) formulation, 2 mg/mL dexamethasone (n = 10), control vehicle X (n = 10), 0.2% hyaluronic acid (n = 10), or no treatment (n = 10). Eye wiping, phenol red, and Cochet Bonnet tests assessed ocular pain, tear fluid secretion, and nerve function. After 7 days, the mice were euthanized to quantify leukocyte infiltration and corneal nerve density.

Results

Topical aprepitant X1 reduced BAK-induced corneal damage and pain compared to gel vehicle X (P = 0.007) and dexamethasone (P = 0.021). Aprepitant X1 and X2 improved corneal sensitivity versus gel vehicle X and dexamethasone (P < 0.001). Aprepitant X1 reduced leukocyte infiltration (P < 0.05) and enhanced corneal nerve density (P < 0.001). Tear fluid secretion remained statistically unchanged in both the X1 and X2 groups.

Conclusions

Aprepitant formulation X1 reduced pain, improved corneal sensitivity and nerve density, ameliorated epitheliopathy, and reduced leukocyte infiltration in male mouse corneas.

Translational Relevance

Aprepitant emerges as a safe, promising therapeutic prospect for the amelioration of DED's associated symptoms.

Biodegradable microneedle acupuncture has equivalent efficacy to traditional intradermal acupuncture for dry eye disease: A pilot single-blinded, randomized controlled trial

BACKGROUND

Dry eye disease (DED) is a common ocular disorder in which the tear film cannot maintain homeostasis. Acupuncture has been used to treat DED in Korean medicine. Particularly, intradermal acupuncture (IDA) is less painful and enables free movement after treatment. However, it can also provoke allergic reactions to metal. To overcome this, biodegradable microneedle acupuncture (BMA) has been developed. This study compared BMA with traditional IDA in terms of efficacy and safety in patients with DED.

METHODS

This study was designed as an investigator-initiated, assessor-blinded, single-center, parallel randomized controlled trial. Thirty patients with DED were enrolled and randomized to one of the treatments. One group was treated with BMA on the acupoints, including bilateral BL2, GB14, TE23, EX-HN5, and ST1. The other group was treated with traditional IDA at the same acupoints. Treatments were conducted 3 times a week for 4 weeks. The major endpoint was ocular surface disease index (OSDI). The minor endpoints were subjective symptoms visual analog scale (VAS), quality of life (QoL), and tear production measured by the Schirmer I test.

RESULTS

All enrolled participants successfully completed the trial, and all of their data was analyzed. Both treatments remarkably improved the OSDI score, VAS score, QoL score, and tear secretion after 4 weeks (P < .05). Except for tear production in the left eye (P < .05), there were no statistical differences between the 2 treatments on the final visit (P > .05). No adverse events were observed.

CONCLUSION

BMA and IDA had the same therapeutic effect for improving DED and both were safe. BMA can be used in patients with DED as an alternative to traditional IDA.

Allogeneic mesenchymal stem cell therapy for dry eye disease in patients with Sjögren's syndrome: A randomized clinical trial

PURPOSE

This double-blinded randomized clinical trial aimed to evaluate the efficacy of injecting allogeneic adipose-derived mesenchymal stem cells (ASCs) into the lacrimal gland (LG) for the treatment of dry eye disease (DED) secondary to Sjögren's syndrome (SS).

METHODS

Fifty-four participants with severe DED secondary to SS were included and allocated to either ASCs (n = 20), vehicle (n = 20), or a non-randomized observation group (n = 14). The intervention groups received a single injection of either ASCs or an active comparator (vehicle, Cryostor® CS10) into the LG in one eye, while the observation group received lubricating eye drops only. The primary outcome measure was changes in Ocular Surface Disease Index (OSDI) score and secondary outcome measures were non-invasive tear break-up time, tear meniscus height, Schirmer's test, and Oxford score within a 12-month follow-up.

RESULTS

A significant reduction in OSDI score was observed in the ASCs and vehicle groups compared to the observation group. In addition, the ASCs group demonstrated a significant increase in non-invasive tear break-up time compared to the vehicle group at the 4-week follow-up and to the observation group at the 12-month follow-up. A significant improvement in ocular surface staining, tear osmolarity, and Schirmer test score from baseline was also observed in the ASCs group; however, these changes were not significant compared to the other groups.

CONCLUSION

Improvement of subjective and objective signs and symptoms of DED was observed in both intervention groups following injection into the LG compared to the observation group. Future studies should investigate the mode-of-action of both injection treatments.

Ocular lesions in patients with ulcerative colitis

OBJECTIVE

Aim: To analyze the data and evaluate the prevalence of ocular lesions in patients with moderate ulcerative colitis.

PATIENTS AND METHODS

Materials and Methods: We observed 112 patients aged 18-75 years old with clinically, endoscopically and histologically confirmed moderate ulcerative colitis which lasted at least 6 months. An ophthalmologic exam was performed to determine the presence of ocular symptoms.

RESULTS

Results: Of the 112 patients with moderate ulcerative colitis, 21 (18,75%) had the following ocular lesions: episcleritis - 7 patients (6,25%), keratopathy - 5 patients (4,46%), uveitis - 5 patients (4,46%), cataract - 2 (1,78%) and scleritis - 2 (1.78%).

CONCLUSION

Conclusions: Because ocular symptoms in patients with UC are often nonspecific, it may be beneficial to perform ophthalmologic examinations as a routine follow-up component of in such patients.

Therapeutic effects of low-color-temperature light-emitting diodes on dry eye

BACKGROUND

As a new technology for treating dry eye diseases, phototherapy has attracted great attention, but the research on its safety and effectiveness is limited. In this study, the therapeutic effects of low-color-temperature light-emitting diodes on dry eye in humans, rabbits, and rats were investigated.

METHODS

In clinical experiments, subjects in both groups read the same paper for 3 h under light sources of two color temperatures: 1900 K (low-color-temperature light-emitting diodes) or 4000 K (artificial fluorescent white light-emitting diodes). The differences in the non-invasive tear film breakup time, tear meniscus height, and conjunctival congestion scores before and after the experiment were compared between the two groups. In animal experiments, corneal epithelial barrier function and tear production of Sprague-Dawley rats and New Zealand white rabbits with dry eye were compared before and after low-color-temperature light-emitting diodes treatment. TUNEL staining and Western blotting were used to detect the apoptosis of corneal and conjunctival cells and the expression of inflammatory factor IL-1β.

RESULTS

Low-color-temperature light-emitting diodes prolonged tear film breakup time in patients with dry eye. Moreover, it increased tear secretion, decreased fluorescein sodium staining scores, corneal and conjunctival cell apoptosis, and inflammatory factor expression in rabbits and rats with dry eye.

CONCLUSIONS

Low-color-temperature light-emitting diodes phototherapy can be used as an effective treatment for dry eye, reducing its symptoms and related ocular surface damage in humans, rabbits, and rats.

Potential of mesenchymal stem cell-derived conditioned medium/secretome as a therapeutic option for ocular diseases

Research has shown that the therapeutic effect of mesenchymal stem cells (MSCs) is partially due to its secreted factors as opposed to the implantation of the cells into the treated tissue or tissue replacement. MSC secretome, especially in the form of conditioned medium (MSC-CM) is now being explored as an alternative to MSCs transplantation. Despite the observed benefits of MSC-CM, only a few clinical trials have evaluated it and other secretome components in the treatment of eye diseases. This review provides insight into the potential therapeutic use of MSC-CM in eye conditions, such as corneal diseases, dry eye, glaucoma, retinal diseases and uveitis. We discuss the current evidence, some limitations, and the progress that remains to be achieved before clinical translation becomes possible.

Organotypic culture model of mouse meibomian gland as a screening platform for risk factors related to meibomian gland dysfunction

PURPOSE

Meibomian glands (MGs) are crucial for maintaining tear film stability and ocular surface health. Here, we aim to establish a novel organotypic culture model of MGs and explore the risk factors of MG dysfunction (MGD).

METHODS

We developed a novel organotypic culture model for MGs at the air-liquid interface. The viability and cell proliferation of MGs were assessed using CCK-8, immunofluorescence, and qPCR. Lipid accumulation was evaluated by Nile red staining and microscopic examination. Protein expression levels were evaluated by immunofluorescence and Western blot assay. EdU assay was employed to track the proliferation of acinar cells. The validity of the model was confirmed through culturing MGs from mice of different ages and incorporating certain drugs (Dex) into the culture system.

RESULTS

Utilizing the novel culture model, the MG tissue exhibited sustained viability, cellular division, and continuous production of lipids for a duration of 7 days. Lipid droplets formed were directly visualized using light field microscopy. Through the cultivation of aged mice's MGs, it was discovered that aging resulted in diminished proliferation and lipid synthesis, along with an aberrant increase in Krt10 expression. Further application of this model showed that Dex treatment diminished MG's proliferation and lipid synthesis. Finally, an in vivo study was conducted to provide additional confirmation of the phenomenon of Dex-induced abnormalities.

CONCLUSIONS

In this study, a stable organotypic culture model of the MGs was established. The organotypic culture model offers a valuable tool to investigate the pathophysiological mechanisms and facilitate drug screening for MG-related diseases.

Advances in the applications of mesenchymal stem cell-conditioned medium in ocular diseases

Mesenchymal stem cell-conditioned medium (MSC-CM), also known as secretome, is secreted by MSC and contains a variety of bioactive factors with anti-inflammatory, anti-apoptotic, neuroprotection, and proliferation effects. Increasing evidence proved that MSC-CM plays an important role in various diseases, including skin, bone, muscle, and dental diseases. However, the role of MSC-CM in ocular diseases is not quite clear, Therefore, this article reviewed the composition, biological functions, preparation, and characterization of MSC-CM and summarized current research advances in different sources of MSC-CM in corneal and retinal diseases, including dry eye, corneal epithelial damage, chemical corneal injury, retinitis pigmentosa (RP), anterior ischemic optic neuropathy (AION), diabetic retinopathy (DR), and other retinal degenerative changes. For these diseases, MSC-CM can promote cell proliferation, reduce inflammation and vascular leakage, inhibit retinal cell degeneration and apoptosis, protect corneal and retinal structures, and further improves visual function. Hence, we summarize the production, composition and biological functions of MSC-CM and focus on describing its mechanisms in the treatment of ocular diseases. Furthermore, we look at the unexplored mechanisms and further research directions for MSC-CM based therapy in ocular diseases.

Chloroquine and Hydroxychloroquine in the Treatment of Dry Eye Disease

The role of chloroquine (CQ) and hydroxychloroquine (HCQ) in the management of dry eye disease is still unclear. This systematic review and meta-analysis investigates the efficacy and feasibility of CQ and HCQ in patients with dry eye disease. In February 2023, PubMed, Embase, Google Scholar, and Web of Science were accessed. Data from 462 patients (mean age 54.4 ± 2.8 years) were collected. Compared to baseline, the tear breakup time (p < 0.0001) and Schirmer I test (p < 0.0001) were significantly increased, and the Ocular Surface Disease Index (OSDI, p < 0.0001) and corneal staining (p < 0.0001) were significantly decreased at the last follow-up in the CQ/HCQ group. At the last follow-up, the OSDI was significantly lower in the CQ/HCQ group compared to the control group (p < 0.0001). Corneal staining was significantly greater in the control group compared to the CQ/HCQ group (p < 0.0001). The Schirmer I test showed no significant difference between the groups (p = 0.2). Altogether, CQ and HCQ improved the symptoms and signs of dry eye disease.

Protective effect of ZYMT, a traditional Chinese patent medicine in a mouse model of retinitis pigmentosa

Retinitis pigmentosa (RP) is the most common genetic disorder that causes blindness. At present, there exists no remedy for the disease. The aim of the current research was to investigate the protective effect of Zhangyanming Tablets (ZYMT) in a mouse model of RP, and explore the underlying mechanism. Eighty RP mice were randomly divided into two groups. The mice in ZYMT group were administered with ZYMT suspension(0.0378 g/mL), while the mice in model group were given the same volume of distilled water. At day 7 and day 14 after intervention, electroretinogram (ERG), fundus photography, and histological examination were used to assess the retinal function and structure. TUNEL, immunofluorescence and qPCR were used to evaluate cell apoptosis and expressions of Sirt1, Iba1, Bcl-2, Bax and Caspase-3. A significantly shortened latency of ERG waves was observed in ZYMT-treated mice, in comparison to those in the model group (P < 0.05). Histologically, ultrastructure of the retina was better preserved, and the outer nuclear layer (ONL) exhibited marked increase in thickness and cell count in ZYMP group (P < 0.05). The apoptosis rate was decreased markedly in ZYMT group. Immunofluorescence analysis showed that the expressions of Iba1 and Bcl-2 in the retina were increased, Bax and Caspase-3 were decreased after ZYMT intervention, while the qPCR revealed that the expressions of Iba1 and Sirt1 were significantly increased (P < 0.05). This study indicated that ZYMT has protective effect on retinal function and morphology of inherited RP mice in the early stage, possibly mediated via the regulation of antioxidant and anti-/pro-apoptotic factors expressions.

Honey-Related Treatment Strategies in Dry Eye Disease

This systematic review and meta-analysis investigated whether honey-related treatment strategies improve the signs and symptoms of patients with dry eye disease (DED). In March 2023, the following databases were accessed for clinical trials investigating the efficacy of honey-related treatment strategies in DED: PubMed, Web of Science, Google Scholar, and EMBASE. The following data were extracted at baseline and at the last follow-up: Ocular Surface Disease Index, tear breakup time, Schirmer I test, and corneal staining. Data from 323 patients were retrieved (53.3% female, mean age 40.6 ± 18.1 years). The mean follow-up was 7.0 ± 4.2 weeks. All the endpoints of interest significantly improved from baseline to the last follow-up: tear breakup time (p = 0.01), Ocular Surface Disease Index (p < 0.0001), Schirmer I test (p = 0.0001), and corneal staining (p < 0.0001). No difference was found in tear breakup time (p = 0.3), Ocular Surface Disease Index (p = 0.4), Schirmer I test (p = 0.3), and corneal staining (p = 0.3) between the honey-related treatment strategies and the control groups. According to our main results, honey-related treatment strategies are effective and feasible to improve symptoms and signs of DED.

In situ formation of injectable organogels for punctal occlusion and sustained release of therapeutics: design, preparation, in vitro and in vivo evaluation

The treatment of dry eye mainly includes instillation of cyclosporine A (CsA) nanoemulsion or the use of punctal plugs. Therefore, in this study, a novel injectable in situ organogel plug was developed using CsA as a model drug, stearic acid, injectable soybean oil, and N-methyl-2-pyrrolidinone (NMP) (1.25:10:0.6, w/v/v) as gel materials, to provide a dual mechanism for dry eye treatment. The formulated CsA injectable in situ organogel (CsA-OG) was evaluated in terms of stability, in vitro release, rheology, ocular irritation, punctal occlusion tests, and ocular distribution assessment. In vivo ocular distribution investigations showed that CsA-OG achieved considerably higher C_max (1.94, 1.92 and 1.97-fold respectively) and AUC_0-72h in the cornea, conjunctiva, and sclera (2.49, 2.27 and 2.15-fold respectively) than ciclosporin eye drops (p < 0.05). In vitro model evaluation demonstrated significant decrease in flow flux to 52.78% at 2 min after CsA-OG injection. According to evaluation of the in vivo model, the organogel plug can completely block the lacrimal passages and greatly decrease the lacrimal drainage rate (p < 0.05). The above results suggest that these intracanalicular CsA-OG plugs can offer more extensive clinical applications than existing lacrimal drainage plugs and may act as a drug delivery system.

Role of topical and systemic immunosuppression in aqueous-deficient dry eye disease

Immunosuppression in aqueous-deficient dry eye disease (ADDE) is required not only to improve the symptoms and signs but also to prevent further progression of the disease and its sight-threatening sequelae. This immunomodulation can be achieved through topical and/or systemic medications, and the choice of one drug over the other is determined by the underlying systemic disease. These immunosuppressive agents require a minimum of 6-8 weeks to achieve their beneficial effect, and during this time, the patient is usually placed on topical corticosteroids. Antimetabolites such as methotrexate, azathioprine, and mycophenolate mofetil, along with calcineurin inhibitors, are commonly used as first-line medications. The latter have a pivotal role in immunomodulation since T cells contribute significantly to the pathogenesis of ocular surface inflammation in dry eye disease. Alkylating agents are largely limited to controlling acute exacerbations with pulse doses of cyclophosphamide. Biologic agents, such as rituximab, are particularly useful in patients with refractory disease. Each group of drugs has its own side-effect profiles and requires a stringent monitoring schedule that must be followed to prevent systemic morbidity. A customized combination of topical and systemic medications is usually required to achieve adequate control, and this review aims to help the clinician choose the most appropriate modality and monitoring regimen for a given case of ADDE.

Involvement of endoplasmic reticulum stress in trigeminal ganglion corneal neuron injury in dry eye disease

Dry eye disease (DED) is a multifactorial disease with a high prevalence worldwide. Uncomfortable corneal sensations severely affect daily life in DED patients. Hence, corneal neuron injury is a vital pathogenesis in DED. Notably, endoplasmic reticulum stress (ERS) plays a role in peripheral neuron injury. However, the role of ERS in DED corneal neuron injury is still far from being clear. In this study, we established an environmental DED (eDED) model in vivo and a hyperosmotic DED model in vitro. Subsequently, trigeminal ganglion (TG) corneal neurons were retrograde labeled by WGA-Alexa Fluor 555, and fluorescence-activated cell sorting was used to collect targeted corneal neurons for RNA sequencing in mice. Our results revealed that TG corneal neuron injury but not apoptosis in DED. ERS-related genes and proteins were upregulated in TG corneal neurons of the eDED mice. ERS inhibition alleviated TG corneal neuron's ERS-related injury. Therefore, ERS-induced TG corneal neuron injury may be an important pathomechanism and provide a promising therapeutic approach to DED.

Serial Sessions of a Novel Low-Level Light Therapy Device for Home Treatment of Dry Eye Disease

INTRODUCTION

This study aimed to evaluate the changes that a recently developed at-home device using low-level light therapy (LLLT) produced in signs and symptoms of patients with dry eye disease (DED) owing to meibomian gland dysfunction (MGD).

METHODS

In this prospective study, patients with DED owing to MGD not successfully responding to first-line therapy (tear substitutes and eye lid hygiene) were treated with four serial sessions (every other day) of mask based on LLLT technology and dedicated for home use (my-mask^®, Espansione Marketing S.p.A., Bologna, Italy). Non-invasive ocular surface examination was carried out by means of Keratograph 5M (Oculus, Wetzlar, Germany) before and after four mask sessions for the evaluation of (i) tear meniscus height (TMH); (ii) first and average non-invasive Keratograph breakup time (NIKBUT); (iii) meibomian gland loss (MGL). Ocular Surface Disease Index (OSDI) questionnaire was used to assess ocular discomfort symptoms.

RESULTS

Overall, 17 patients (3 male, 14 female; mean age 61.47 ± 11.93 years) were enrolled and all of them regularly completed the entire cycle of four sessions without reporting any adverse event. The mean values of NIKBUT first and NIKBUT average increased significantly after treatment (from 5.29 ± 2.60 at T0 to 9.04 ± 3.49 s at T1 [P = 0.001] and from 9.40 ± 3.81 to 11.28 ± 2.81 s [P = 0.017]); in parallel, the mean value of TMH increased significantly from 0.27 ± 0.06 to 0.32 ± 0.09 mm (P = 0.029). Conversely, there were not statistically significant differences for MGL (P = 0.346). In addition, the mean value of OSDI score decreased after treatment (from 32.00 ± 7.96 at T0 to 20.71 ± 8.03 at T1; P < 0.001).

CONCLUSIONS

One week of serial sessions of a newly developed LLLT device for home use significantly improved tear film production and stability along with ocular discomfort symptoms in patients with DED owing to MGD. These findings open up a new scenario for patients with MGD who can enjoy the unique benefits of LLLT at home.

A Critical Appraisal of the Physicochemical Properties and Biological Effects of Artificial Tear Ingredients and Formulations

Dry eye disease is among the most prevalent diseases affecting the ocular surface. Artificial tears remain the cornerstone therapy for its management. There are currently a wide variety of marketed artificial tears available to choose from. These artificial tears differ significantly in their composition and formulation. This article reviews the physicochemical and biological properties of artificial tear components and how these characteristics determine their use and efficacy in the management of dry eye. Furthermore, this article also discusses the various formulations of artificial tears such as macro and nanoemulsion and the type of preservatives present in them.

Dry eye disease in mice activates adaptive corneal epithelial regeneration distinct from constitutive renewal in homeostasis

Many epithelial compartments undergo constitutive renewal in homeostasis but activate unique regenerative responses following injury. The clear corneal epithelium is crucial for vision and is renewed from limbal stem cells (LSCs). Using single-cell RNA sequencing, we profiled the mouse corneal epithelium in homeostasis, aging, diabetes, and dry eye disease (DED), where tear deficiency predisposes the cornea to recurrent injury. In homeostasis, we capture the transcriptional states that accomplish continuous tissue turnover. We leverage our dataset to identify candidate genes and gene networks that characterize key stages across homeostatic renewal, including markers for LSCs. In aging and diabetes, there were only mild changes with <15 dysregulated genes. The constitutive cell types that accomplish homeostatic renewal were conserved in DED but were associated with activation of cell states that comprise "adaptive regeneration." We provide global markers that distinguish cell types in homeostatic renewal vs. adaptive regeneration and markers that specifically define DED-elicited proliferating and differentiating cell types. We validate that expression of SPARC, a marker of adaptive regeneration, is also induced in corneal epithelial wound healing and accelerates wound closure in a corneal epithelial cell scratch assay. Finally, we propose a classification system for LSC markers based on their expression fidelity in homeostasis and disease. This transcriptional dissection uncovers the dramatically altered transcriptional landscape of the corneal epithelium in DED, providing a framework and atlas for future study of these ocular surface stem cells in health and disease.

Lifestyle and Symptom Risk Factors for Dry Eye Disease in Asian Gout Population: A Population-Based Case-Control Study

We aim to investigate the lifestyle and symptom factors related to dry eye disease (DED) presence in patients with persistent gout using the Taiwan Biobank (TWB) database. A retrospective case-control study was conducted, and patients with a history of gout longer than 10 years were enrolled in the persistent-gout group. Each persistent-gout patient was age- and sex-matched to two non-gout individuals who served as the control group, and we included a total of 973 and 1946 patients in the persistent-gout group and non-gout groups. The main outcome of our study is the presence of DED and the distribution of several lifestyle and symptom risk factors of DED in persistent-gout and non-gout individuals. Logistic regression considering the age and sex and interaction test was applied to estimate the correlation of each lifestyle and symptom risk factor to DED in the two groups. A total of 95 and 140 DED events were found in the persistent-gout and non-gout groups, with a significantly higher percentage in the persistent-gout population (aOR: 1.167, 95% CI: 1.073-3.855, p = 0.0415). The visual display terminal (VDT) user (p = 0.0026) and persistent alcohol drinking (p = 0.0384) were associated with DED more often in the persistent-gout population than the non-gout population. Moreover, the percentages of DED in the patients with gout intervals of 10-20 years and more than 20 years were statistically insignificant (aOR: 1.042, 95% CI: 0.886-1.910, p = 0.5279). In conclusion, VDT usage and persistent alcohol drinking are prominent lifestyle and symptom risk factors for DED occurrence in patients who have experienced gout for more than 10 years.

Association between poor sleep quality and an increased risk of dry eye disease in patients with obstructive sleep apnea syndrome

Purpose

Obstructive sleep apnea (OSA) is related to an increased incidence of dry eye disease (DED). However, their exact relationship is unknown and requires further well-designed studies with advanced mechanisms detection.

Patients and methods

This case–control study included 125 OSA cases and 125 age–gender-matched controls enrolled in the hospital between 1 January and 1 October 2021. OSA diagnosis and classification were performed using a polysomnography (PSG) assay. Detailed ophthalmological examinations, including the Schirmer I test, corneal staining, and ocular surface disease index (OSDI), were used to detect DED-related parameters. A comprehensive ocular surface assay was performed to measure a series of parameters, including first non-invasive first tear film break-up time (f-NIBUT), average non-invasive first tear film break-up time (av-NIBUT), tear meniscus height (TMH), and loss of meibomian gland. In addition, the Pittsburgh Sleep Quality Index (PSQI) scale was used to assess sleep quality.

Results

Compared to the control, the OSA group showed an increased DED risk (P = 0.016) along with an increased PSQI score and a higher rate of poor quality sleep (P < 0.001 and P = 0.007, respectively). Stratification of OSA cases indicated that DED-related parameters were impaired in patients with severe OSA (P < 0.05). The analysis of DED-parameters-related factors showed significant correlations between OSA-related indexes and PSQI (P < 0.05). Moreover, the poor sleep quality group in the OSA cases showed worse DED-related parameters (P < 0.05), which was not observed in the control group.

Conclusion

OSA, especially the severe stage OSA, was related to an increased risk of DED. Also, sleep quality was correlated with the onset of both OSA and DED, where poor sleep quality revealed a relationship between OSA and the risk of DED. Overall, our findings provided evidence for advanced management of DED and OSA in future.

Corneal Neuro-Regenerative Effect of Transcutaneous Electrical Stimulation in Rabbit Lamellar Keratectomy Model

Purpose

This study aimed to evaluate the effect of transcutaneous electrical stimulation (TES) on corneal nerve regeneration in rabbits injured from superficial lamellar keratectomy (SLK).

Methods

New Zealand White rabbits were used in this experimental study. To induce corneal nerve damage, SLK was performed using a 7.0-mm trephine. TES was applied for 28 days after the corneal nerve injury. Corneal sensitivity, Western blotting, real-time polymerase chain reaction (PCR), and immunofluorescence were performed to observe changes in the corneal tissue.

Results

In the 2-Hz and 20-Hz electrical stimulation groups, the degree of corneal wound healing increased by more than 10% compared to the control group, but no significant difference was observed. Conversely, the electrical stimulation (2-Hz or 20-Hz) group showed significantly increased corneal sensitivity compared to the control group. Western blot analysis revealed that small proline-rich protein 1A (SPRR1a), a regeneration-associated protein was significantly increased in the 2-Hz group on days 1 and 7 compared to that in the other groups. Once again, nerve regeneration in the 2-Hz group was supported by the results of PCR, in which a significant increase in the nerve growth factor (NGF) on day 1 was observed compared with the other groups. Moreover, immunofluorescence after 28 days of electrical stimulation showed significant nerve regeneration in the 2-Hz group.

Conclusions

TES promoted corneal nerve regeneration in rabbit SLK model. The application of electrical stimulation of 2-Hz frequency was more effective than the 20-Hz frequency, showing potential clinical applications for corneal diseases.

Translational Relevance

This study shows how application of TES to the eyes that exhibit corneal nerve damage can improve corneal nerve regeneration examined by histologic analysis.

Effect of Intense Pulsed Light Therapy in Dry Eye Disease Caused by Meibomian Gland Dysfunction: A Systematic Review and Meta-Analysis

BACKGROUND

This study aimed to systematically evaluate the effect of intense pulsed light (IPL) therapy in patients harboring dry eye disease caused by meibomian gland dysfunction (MGD) based on qualified studies.

METHODS

The electronic databases, including PubMed, Cochrane, and Embase, were searched using keywords to identify available publications updated to November 2021. Relative risk or weighted mean difference combined with 95% confidence interval was used to synthesize the outcomes of included studies. The meta-analysis included 15 randomized controlled trials with 1,142 patients (2,284 eyes).

RESULTS

The results revealed that IPL could significantly decrease the ocular surface disease index (OSDI), standard patient evaluation of eye dryness (SPEED), artificial tear usage, tear film lipid layer, meibomian gland quality (MGQ), meibomian gland expression (MGX), and corneal fluorescein staining (CFS) while increase tear break-up time (TBUT) and noninvasive tear break-up time (NIBUT) compared with sham. Compared with MGX, IPL+MGX markedly decreased the SPEED, CFS, and tear meniscus height (TMH), but with increased TBUT. Compared with MGX, IPL showed significant effect in increasing the OSDI and TBUT, but decreasing the TMH and NIBUT. However, no significant differences were seen between IP+MGX and MGX in OSDI, MGQ, and MGX, nor between IPL and MGX in OSDI, SPEED, and TBUT.

CONCLUSION

We identified that the application of IPL alone or IPL combined with MGX elicited superior clinical effect for improving the eye function and symptoms in the treatment of MGD-related dry eye disease, which is considered available for wide clinical application.

Neurostimulation for dry eye disease

PURPOSE OF REVIEW

To review the neuroanatomy and physiology of the basal and reflex tearing and present the available and developing therapies using the concept of neurostimulation in dry eye disease (DED).

RECENT FINDINGS

The most prevalent current DED treatments seek to supplement low tear volume and tear components or reduce inflammation. Neurostimulation is a unique approach gaining momentum in recent years, geared toward increasing the production of all basal tear components by stimulating the nerves responsible for producing the various tear components. The neuroanatomy of the lacrimal unit provides several possible access points to stimulate tear production through two arms of the sensory trigeminal nerves. Modes of stimulation include chemical or energy in electrical or magnetic form. Research thus far has shown that neurostimulation can achieve lacrimal, goblet cell, and meibomian gland stimulation. Subjectively it improves symptoms of DED. Clinically, neurostimulation has improved the signs and symptoms of DED by increasing basal tear production and tear volume.

SUMMARY

Neurostimulation using electrical, mechanical, or chemical means is a novel concept to increase tear production and was demonstrated to be an effective, safe, and well-tolerated method for managing DED.

Bacteria and Dry Eye: A Narrative Review

(1) Background: Dry eye is a multifactorial disease of the ocular surface, the incidence of which has been increasing sharply. The pathogenesis of dry eye, especially in terms of the bacterial flora, has drawn great attention. Additionally, the potential treatment methods need to be explored. (2) Methods: We reviewed more than 100 studies and summarized them briefly in a review. (3) Results: We summarized the bacterial communities found on the ocular surface in the general population and patients with dry eye and found a relationship between dry eye and antibiotic therapy. We identified the possible mechanisms of bacteria in the development of dry eye by discussing factors such as the destruction of the antibacterial barrier, infectious diseases, microbiome homeostasis, inflammatory factors on the ocular surface and vitamin deficiency. (4) Conclusion: We systematically reviewed the recent studies to summarize the bacterial differences between patients with dry eye and the general population and brought up several possible mechanisms and possible treatment targets.

Current Advances in Mechanisms and Treatment of Dry Eye Disease: Toward Anti-inflammatory and Immunomodulatory Therapy and Traditional Chinese Medicine

Dry eye is currently one of the most common ocular surface disease. It can lead to ocular discomfort and even cause visual impairment, which greatly affects the work and quality of life of patients. With the increasing incidence of dry eye disease (DED) in recent years, the disease is receiving more and more attention, and has become one of the hot research fields in ophthalmology research. Recently, with the in-depth research on the etiology, pathogenesis and treatment of DED, it has been shown that defects in immune regulation is one of the main pathological mechanisms of DED. Since the non-specific and specific immune response of the ocular surface are jointly regulated, a variety of immune cells and inflammatory factors are involved in the development of DED. The conventional treatment of DED is the application of artificial tears for lubricating the ocular surface. However, for moderate-to-severe DED, treatment with anti-inflammatory drugs is necessary. In this review, the immunomodulatory mechanisms of DED and the latest research progress of its related treatments including Chinese medicine will be discussed.

Differential Effects of Treatment Strategies in Individuals With Chronic Ocular Surface Pain With a Neuropathic Component

Background: Dysfunction at the ocular system via nociceptive or neuropathic mechanisms can lead to chronic ocular pain. While many studies have reported on responses to treatment for nociceptive pain, fewer have focused on neuropathic ocular pain. This retrospective study assessed clinical responses to pain treatment modalities in individuals with neuropathic component ocular surface pain. Methods: 101 individuals seen at the University of Miami Oculofacial Pain Clinic from January 2015 to August 2021 with ≥3 months of clinically diagnosed neuropathic pain were included. Patients were subcategorized (postsurgical, post-traumatic, migraine-like, and laterality) and self-reported treatment outcomes were assessed (no change, mild, moderate, or marked improvement). One-way ANOVA (analysis of variance) was used to examine relationships between follow up time and number of treatments attempted with pain improvement, and multivariable logistic regression was used to assess which modalities led to pain improvement. Results: The mean age was 55 years, and most patients were female (64.4%) and non-Hispanic (68.3%). Migraine-like pain (40.6%) was most common, followed by postsurgical (26.7%), post-traumatic (16.8%) and unilateral pain (15.8%). The most common oral therapies were α2δ ligands (48.5%), the m common topical therapies were autologous serum tears (20.8%) and topical corticosteroids (19.8%), and the most common adjuvant was periocular nerve block (24.8%). Oral therapies reduced pain in post-traumatic (81.2%), migraine-like (73%), and unilateral (72.7%) patients, but only in a minority of postsurgical (38.5%) patients. Similarly, topicals improved pain in post-traumatic (66.7%), migraine-like (78.6%), and unilateral (70%) compared to postsurgical (43.7%) patients. Non-oral/topical adjuvants reduced pain in postsurgical (54.5%), post-traumatic (71.4%), and migraine-like patients (73.3%) only. Multivariable analyses indicated migraine-like pain improved with concomitant oral α2δ ligands and adjuvant therapies, while postsurgical pain improved with topical anti-inflammatories. Those with no improvement in pain had a shorter mean follow-up (266.25 ± 262.56 days) than those with mild (396.65 ± 283.44), moderate (652 ± 413.92), or marked improvement (837.93 ± 709.35) (p < 0.005). Identical patterns were noted for number of attempted medications. Conclusion: Patients with migraine-like pain frequently experienced pain improvement, while postsurgical patients had the lowest response rates. Patients with a longer follow-up and who tried more therapies experienced more significant relief, suggesting multiple trials were necessary for pain reduction.

GlicoPro, Novel Standardized and Sterile Snail Mucus Extract for Multi-Modulative Ocular Formulations: New Perspective in Dry Eye Disease Management

This study aimed to evaluate the mucoadhesive and regenerative properties of a novel lubricating multimolecular ophthalmic solution (GlicoPro^®) extracted from snail mucus and its potential anti-inflammatory and analgesic role in the management of dry eye disease (DED). GlicoPro bio-adhesive efficacy was assessed using a lectin-based assay, and its regenerative properties were studied in a human corneal epithelial cell line. In vitro DED was induced in human corneal tissues; the histology and mRNA expression of selected genes of inflammatory and corneal damage biomarkers were analyzed in DED tissues treated with GlicoPro. A higher percentage of bio-adhesivity was observed in corneal cells treated with GlicoPro than with sodium hyaluronate-based compounds. In the scratch test GlicoPro improved in vitro corneal wound healing. Histo-morphological analysis revealed restoration of cellular organization of the corneal epithelium, microvilli, and mucin network in DED corneal tissues treated with GlicoPro. A significant reduction in inflammatory and ocular damage biomarkers was observed. High-performance liquid chromatography-mass spectrometry analysis identified an endogenous opioid, opiorphin, in the peptide fraction of GlicoPro. In conclusion, GlicoPro induced regeneration and bio-adhesivity in corneal cells; moreover, considering its anti-inflammatory and analgesic properties, this novel ophthalmic lubricating solution may be an innovative approach for the management of DED.