Enhanced Tearing by Electrical Stimulation of the Anterior Ethmoid Nerve

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.

Efficacy and Safety of Quantum Molecular Resonance Electrotherapy in Patients with Aqueous-Deficient, Evaporative and Mixed-Type Dry Eye: A Randomized Interventional Study

INTRODUCTION

To evaluate the efficacy and safety of Quantum Molecular Resonance (QMR) treatment in patients with severe dry eye disease (DED), as well as its effects on aqueous-deficient (ADDE), evaporative (EDE), and mixed (MDE) dry eye.

METHODS

In this prospective, interventional study, 81 patients were randomly allocated to received four treatment sessions of QMR at 1-week intervals (Rexon-Eye®, Resono Ophthalmic, Trieste, Italy) (QRM group) or tear substitute four times daily, containing 0.15% sodium hyaluronate and 3% trehalose (Thealoz Duo®, Thea Pharma, France) (SH-TH group). Outcome measures included ocular surface disease index (OSDI) questionnaire, tear meniscus height (TMH), tear breakup time (TBUT), non-invasive breakup time (NIBUT), corneal fluorescein staining (CFS), lipid layer thickness (LLT), tear film osmolarity (OSM), and meibomian gland dysfunction (MGD) grade, which were assessed at baseline and 1-month and 3-month follow-up.

RESULTS

The QMR group achieved better improvements than the SH-TH group in OSDI and SANDE questionnaires, NIBUT, LLT, and CFS. The mean differences between the groups were as follows: OSDI (- 12.4 ± 0.25 points, P = 0.01), SANDE (10.6 ± 1.7 points, P = 0.01), NIBUT (2 ± 0.25 s, P = 0.01), LLT (18.7 ± 0.7 nm, P = 0.01), and CFS (1.2 ± 0.1 points, P = 0.02). In subgroups analysis, QMR treatment demonstrated a beneficial role to improve DED symptoms and signs in ADDE, EDE, and MDE.

CONCLUSION

QMR is an effective and well-tolerated treatment that seems to improve DED symptoms and signs in patients with severe DED. However, further studies are needed to confirm this.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT06119386.

TFOS Lifestyle: Impact of elective medications and procedures on the ocular surface

The word "elective" refers to medications and procedures undertaken by choice or with a lower grade of prioritization. Patients usually use elective medications or undergo elective procedures to treat pathologic conditions or for cosmetic enhancement, impacting their lifestyle positively and, thus, improving their quality of life. However, those interventions can affect the homeostasis of the tear film and ocular surface. Consequently, they generate signs and symptoms that could impair the patient's quality of life. This report describes the impact of elective topical and systemic medications and procedures on the ocular surface and the underlying mechanisms. Moreover, elective procedures performed for ocular diseases, cosmetic enhancement, and non-ophthalmic interventions, such as radiotherapy and bariatric surgery, are discussed. The report also evaluates significant anatomical and biological consequences of non-urgent interventions to the ocular surface, such as neuropathic and neurotrophic keratopathies. Besides that, it provides an overview of the prophylaxis and management of pathological conditions resulting from the studied interventions and suggests areas for future research. The report also contains a systematic review investigating the quality of life among people who have undergone small incision lenticule extraction (SMILE). Overall, SMILE refractive surgery seems to cause more vision disturbances than LASIK in the first month post-surgery, but less dry eye symptoms in long-term follow up.

A Microfluidic Contact Lens to Address Contact Lens-Induced Dry Eye

The contact lens (CL) industry has made great strides in improving CL-wearing experiences. However, a large amount of CL wearers continue to experience ocular dryness, known as contact lens-induced dry eye (CLIDE), stemming from the reduction in tear volume, tear film instability, increased tear osmolarity followed by inflammation and resulting in ocular discomfort and visual disturbances. In this article, to address tear film thinning between the CL and the ocular surface, the concept of using a CL with microchannels to deliver the tears from the pre-lens tear film (PrLTF) to the post-lens ocular surface using in vitro eye-blink motion is investigated. This study reports an eye-blink mimicking system with microfluidic poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogel with integrated microchannels to demonstrate eye-blink assisted flow through microchannels. This in vitro experimental study provides a proof-of-concept result that tear transport from PrLTF to post-lens tear film can be enhanced by an artificial eyelid motion in a pressure range of 0.1-5 kPa (similar to human eyelid pressure) through poly(HEMA) microchannels. Simulation is conducted to support the hypothesis. This work demonstrates the feasibility of developing microfluidic CLs with the potential to help prevent or minimize CLIDE and discomfort by the enhanced transport of pre-lens tears to the post-lens ocular surface.

Effectiveness of Intranasal Tear Neurostimulation for Treatment of Dry Eye Disease: A Meta-Analysis

INTRODUCTION

To assess the effectiveness and safety of intranasal tear neurostimulation in the treatment of dry eye disease.

METHODS

We performed a meta-analysis of four databases from their inception to October 2022 without language restrictions. Randomized controlled trials and non-randomized controlled trials meeting the inclusion criteria were included in this review and were quality appraised. The risk of bias was evaluated by two independent reviewers using the Cochrane Collaboration Tool and Methodological Index for Non-Randomized Studies. The random-effect model or fixed-effect model was adopted to estimate the pooled effect sizes.

RESULTS

Fifteen published studies consisting of 17 clinical trials with a total of 901 patients were analyzed. Schirmer II test scores were significantly higher after intranasal tear neurostimulation in patients with dry eye disease (mean difference = 14.12 mm, 95% confidence intervals (8.93, 19.31), P < 0.001). Intranasal tear neurostimulation increased the meibomian gland areas (mean difference = - 251.79 μm², 95% confidence intervals (- 348.34, - 155.23), P < 0.001), but no significant difference was found in meibomian gland perimeters before and after stimulation (mean difference = 3.72 mm, 95% confidence intervals (- 22.14, 29.59), P = 0.78). All adverse events were mild or moderate, and no serious adverse events were reported.

CONCLUSIONS

This meta-analysis provides promising evidence for the controversial effectiveness of intranasal tear neurostimulation in the treatment of dry eye disease, along with useful information for guiding intranasal tear neurostimulation in future clinical trials.

TRIAL REGISTRATION

This meta-analysis was registered on the Prospective Register of Systematic Reviews (PROSPERO) (CRD42021284214).

Matching-adjusted indirect comparison of phase 3 clinical trial outcomes of OC-01 (varenicline solution) nasal spray and lifitegrast 5% ophthalmic solution for the treatment of dry eye disease

BACKGROUND: Matching-adjusted indirect comparison (MAIC) is a methodology for cross-study comparisons after adjusting for baseline characteristic imbalances. It is a comparative analytical approach used across therapeutic areas absent head-to-head trial outcomes. OBJECTIVE: To compare the efficacy of OC-01 (varenicline solution) 0.03 mg nasal spray (OC-01 VNS) to lifitegrast 5% ophthalmic solution on tear production and patient-reported eye dryness in patients with dry eye disease (DED) using data from phase 3 clinical trials via MAIC analysis. METHODS: Individual patient data (IPD) from the phase 3 registrational trial of OC-01 VNS and aggregate data from 2 phase 3 trials of lifitegrast in the publicly available XIIDRA New Drug Application were used. Using unanchored MAIC methods, IPD were weighted on clinically relevant baseline variables (age, race, sex, baseline Schirmer's test score [STS], and Eye Dryness Score [EDS]) to produce weighted OC-01 VNS datasets matched to the same lifitegrast datasets' variables. Least-squares (LS) mean change from baseline (CFB) in STS for OC-01 VNS was calculated using the identical analysis of covariance model and covariates used to calculate the same values for lifitegrast in the XIIDRA New Drug Application and was then compared. LS mean EDS (based on a 100- point Visual Analogue Scale) was compared via analysis of covariance in the weighted OC-01 VNS and lifitegrast datasets. OC-01 VNS at 2 and 4 weeks compared to lifitegrast data at 2 and 6 weeks. RESULTS: Data from 511 subjects (n = 260 treated; 251 vehicle control [VC]) in the OC-01 VNS phase 3 trial, 588 (n = 293 treated, 295 VC) in the lifitegrast phase 3 OPUS-1 trial, and 718 (n = 358 treated, 360 VC) in the lifitegrast phase 3 OPUS-2 trial were analyzed. The LS mean STS CFB for OC-01 VNS at 2 and 4 weeks was significantly greater than that for lifitegrast at 2 and 6 weeks in OPUS-1 and OPUS-2 (P < 0.0001 for all comparisons). The LS mean EDS CFB for OC-01 VNS at 2 and 4 weeks was significantly greater than that for lifitegrast at 2 and 6 weeks in OPUS-1 (P < 0.0001 for both comparisons) and at 4 weeks vs lifitegrast at 6 weeks in OPUS-2 (P < 0.0001). CONCLUSIONS: This MAIC analysis demonstrates OC-01 VNS produced significantly greater improvement in mean STS and comparable or greater improvement in EDS compared with lifitegrast in phase 3 trials. These findings suggest a potentially greater magnitude of improvement achieved with OC-01 VNS compared with lifitegrast for the treatment of DED within the conditions of the analysis methodology. DISCLOSURES D White is a consultant for Oyster Point Pharma, Inc. L Hendrix, M Macsai, and A Gibson are employees and shareholders for Oyster Point Pharma, Inc. L Sun was an employee of COEUS, Clinical Research at the time of study conduct and received funding from Oyster Point Pharma, Inc. I Tam is an employee of COEUS, Clinical Research and received funding from Oyster Point Pharma, Inc. Oyster Point Pharma, Inc was involved in the study design, data collection, data analysis, and preparation of the manuscript and is the manufacturer/licensee of OC-01 (varenicline solution) nasal spray. Oyster Point Pharma, Inc., sponsored the phase 3 OC-01 (varenicline solution) clinical study from which analysis data were obtained.

Eliciting blinks by transcutaneous electric nerve stimulation improves tear fluid in healthy video display terminal users: A self-controlled study

We aimed to elicit strong blinks among healthy video display terminal (VDT) users by periorbital transcutaneous electric nerve stimulation (TENS) and evaluate its impact on the tear fluid and visual task. Appropriate TENS conditions were evaluated to evoke strong blinks under minimum discomfort. Seventeen healthy VDT users with noninvasive Keratograph first breakup time (NIKf-BUT) 5-15 s and Ocular Surface Disease Index (OSDI) scores < 15 were recruited in this study. Before the trial, noninvasive Keratograph average breakup time (NIKa-BUT), tear meniscus height (TMH) and OSDI scores were evaluated. Before each TENS session, the volunteers played Tetris while the corresponding blink rate and Tetris scores were recorded. Then, the participants underwent 30 minutes of TENS, which evoked blinking of their right eye 20 times per minute. Tetris scores were evaluated again during TENS. The Tetris scores and corresponding blink rate were assessed after each TENS session while NIKa-BUT, TMH and OSDI scores were recorded after the third and sixth TENS sessions. We found that OSDI scores declined significantly after the sixth TENS (P = .003). The NIKa-BUT of the right eye was promoted after the sixth TENS (P = .02), and the TMH was higher after the third and sixth TENS in both eyes (P = .03, P = .03 for right eyes respectively, P = .01, P = .01 for left eyes respectively). There was no significant difference between the adjusted Tetris scores before and during TENS (P = .12). The blink rate before and after TENS were unaffected after 6 sessions (P = .61). The results indicated that periorbital TENS effectively ameliorated ocular irritation and improved tear secretion and tear film stability by eliciting strong blinks in healthy VDT users without disturbing the visual task.

Bilateral Effect of OC-01 (Varenicline Solution) Nasal Spray for Treatment of Signs and Symptoms in Individuals with Mild, Moderate, and Severe Dry Eye Disease

PURPOSE

This study compares outcomes of therapy with OC-01 (varenicline solution) for dry eye disease in study eyes and nonstudy fellow eyes of participants in 2 pivotal clinical trials.

METHODS

All 891 patients randomized to receive OC-01 (varenicline solution) 0.03 mg, OC-01 (varenicline solution) 0.06 mg, or vehicle control (VC) in each nostril twice daily for 28 days in the Phase IIb ONSET-1 (Evaluation of the Efficacy of OC-01 Nasal Spray on Signs and Symptoms of Dry Eye Disease) and Phase III ONSET-2 trials were included in this post hoc analysis. One eye was designated as the study eye. The mean change from baseline in anesthetized Schirmer test score (STS) and the percentage of eyes achieving a ≥10-mm STS improvement were compared between treatments in study and fellow eyes overall and by baseline Eye Dryness Score.

FINDINGS

In the study eyes, the mean STS improvement from baseline to day 28 was 10.4 mm, 10.5 mm, and 4.9 mm in the 0.03 mg, 0.06 mg, and VC groups, respectively; comparable values in nonstudy fellow eyes were 8.7 mm, 8.8 mm, and 2.7 mm, respectively. The percentages of study eyes achieving a ≥10-mm STS improvement were 48.1%, 48.4%, and 25.9%, respectively, whereas the comparable values in nonstudy eyes were 42.9%, 43.9%, and 19.7%, respectively. No significant treatment-subgroup interactions were observed in study or fellow eye STS outcomes by baseline Eye Dryness Scores <40 and ≥40 (p > 0.05 for all).

IMPLICATIONS

OC-01 (varenicline solution) nasal spray had significant tear film production improvements compared with VC in both study and fellow eyes. These findings suggest efficacy across a broad spectrum of presenting disease severity.

OC-01 (Varenicline Solution) Nasal Spray Demonstrates Consistency of Effect Regardless of Age, Race, Ethnicity, and Artificial Tear Use

Purpose

To evaluate OC-01 [varenicline solution nasal spray (VNS)] tear production and symptom outcomes in patients with dry eye disease by age, gender, race, ethnicity, and artificial tear use status.

Patients and Methods

Adults ≥22 years of age diagnosed with dry eye disease, with Ocular Surface Disease Index score ≥23, corneal fluorescein staining score ≥2 in ≥1 region or ≥4 for all regions, and baseline Schirmer Test Score (STS) ≤10 mm, with no restrictions on eye dryness score (EDS). Efficacy was assessed using integrated data from ONSET-1 and ONSET-2 [vehicle control (VC), n=294; OC-01 VNS 0.03 mg, n=308]. Subgroups included age (≤55, 56-65, >65 years), gender (male, female), race (White, Black or African American), ethnicity (Hispanic or Latino, Not Hispanic or Latino), and artificial tear use (yes, no). Analysis of covariance models, with the covariates treatment, study site, and baseline severity measures, were used to calculate treatment-VC differences. Consistency of effect among subgroups was evaluated by conducting interaction tests.

Results

Consistency of treatment effect across subgroups was observed for all endpoints, with P value for all treatment-subgroup interaction terms >0.05. For % of patients with ≥10mm improvement in STS and least squares (LS) mean change from baseline in STS and EDS, there was improvement in tear production across demographic group categories. Artificial tear use did not change STS or EDS outcomes with OC-01 VNS.

Conclusion

OC-01 VNS improved tear production and patient-reported symptom outcomes across a broad range of patients by age, gender, race, and ethnicity, and regardless of artificial tear use status at baseline. OC-01 VNS demonstrated a consistent benefit across an extensive range of patients with dry eye disease.

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.

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.

Stimulating Tear Production: Spotlight on Neurostimulation

Dry eye disease (DED) affects up to one-third of the global population. Traditional therapies, including topical lubricants, have been employed with variable success in the treatment of DED. Recently, neurostimulation of the lacrimal functional unit (LFU) has emerged as a promising alternative therapy for DED. In this review, we describe the neuroanatomical and pathophysiological considerations of DED and the LFU that make neurostimulation a viable therapeutic alternative. We further detail the various neurostimulatory approaches taken thus far—from implanted stimulators to external devices to chemical neurostimulation. Existing studies reveal the strengths of the neurostimulatory approach in increasing tear volume and improving dry eye symptoms, but further studies are needed to elucidate its true potential in treatment of DED.

Therapie des Trockenen Auges

Die Therapie des Trockenen Auges stellt eine schwierige Aufgabe für den behandelnden Augenarzt dar. Fortschritte in unserem Verständnis der Risikofaktoren, der Ätiologie und Pathophysiologie des Trockenen Auges haben zu einer Weiterentwicklung der Behandlungsstrategien geführt. Vor Beginn der Therapie ist die korrekte Zuordnung in eine wässrig-muzinöse Tränenfilmdysfunktion (Mindersekretion), in eine lipidbedingte Tränenfilmdysfunktion (hyperevaporative Form durch eine abnormen Meibom-Drüsen-Physiologie) oder in eine variable Kombination wichtig. Unter Berücksichtigung aktueller Empfehlungen der DOG, des BVA und des TFOS DEWS II Unterausschusses wurde ein Behandlungsalgorithmus abgeleitet, der ein schrittweises Vorgehen je nach Schweregrad der Erkrankung darstellt.

Organoids and organ chips in ophthalmology

Recent advances have driven the development of stem cell-derived, self-organizing, three-dimensional miniature organs, termed organoids, which mimic different eye tissues including the retina, cornea, and lens. Organoids and engineered microfluidic organ-on-chips (organ chips) are transformative technologies that show promise in simulating the architectural and functional complexity of native organs. Accordingly, they enable exploration of facets of human disease and development not accurately recapitulated by animal models. Together, these technologies will increase our understanding of the basic physiology of different eye structures, enable us to interrogate unknown aspects of ophthalmic disease pathogenesis, and serve as clinically-relevant surrogates for the evaluation of ocular therapeutics. Both the burden and prevalence of monogenic and multifactorial ophthalmic diseases, which can cause visual impairment or blindness, in the human population warrants a paradigm shift towards organoids and organ chips that can provide sensitive, quantitative, and scalable phenotypic assays. In this article, we review the current situation of organoids and organ chips in ophthalmology and discuss how they can be leveraged for translational applications.

Optical Quality and Tear Film Analysis Before and After Intranasal Stimulation in Patients with Dry Eye Syndrome

Purpose

To evaluate the optical quality and tear film quality in patients with dry eye syndrome (DES) before and after using an intranasal neurostimulation device to stimulate tear production.

Methods

Cross-sectional review of 33 eyes in 21 patients with DES who underwent optical quality and tear film analysis as part of their routine dry eye evaluation pre- and post-neurostimulation trial in office. Optical quality was assessed by measuring the objective scattering index (OSI) and modulation transfer function (MTF). The time to blink and mean tear film OSI were used to analyze the tear film.

Results

Optical quality after the use of the intranasal neurostimulator improved with an average decrease (improvement) in OSI of 0.30±0.68 (P=0.015) and an average increase (improvement) in MTF of 2.12±9.2 (P=0.15). Pre-intranasal neurostimulation OSI had a positive correlation with age (Spearman’s rho 0.60, p < 0.001), while MTF had a negative correlation (Spearman’s rho −0.38, p = 0.03). Pre-intranasal neurostimulation OSI had a negative correlation with MTF (Spearman’s rho −0.85, p < 0.001) and a positive correlation with tear film mean OSI (Spearman’s rho 0.85, p <0.001).

Conclusion

The optical quality of patients with DES is improved with the use of intranasal neurostimulation for tear production, and there was a trend towards improved MTF though not statistically significant. Future studies are needed to follow patients longitudinally.

Intense pulsed light for the treatment of Meibomian gland dysfunction: A systematic review and meta-analysis

Meibomian gland dysfunction (MGD) is frequently encountered by eye care practitioners. It is characterised by obstruction of the Meibomian glands and/or alterations in the consistency of glandular secretions. At present, no definitive treatment exists for this condition. The present meta-analysis was performed to assess the efficacy of intense pulsed light (IPL) therapy in the management of MGD. Databases including EMBASE, PubMed, Cochrane Central, MEDLINE and Google Scholar were systematically searched to identify clinical trials that assessed the efficacy of IPL in the treatment of MGD. Outcome measures were described as the standardized mean difference (SMD). The fixed- or random-effects model was selected for analysis based on the Cochrane I² values representing heterogeneity. Publication bias was visually inspected using Begg's funnel plot. Data were synthesized from four randomized controlled trials (RCTs) comprising 122 subjects in the IPL group and 120 subjects in the control group. Pooled analysis indicated no statistically significant difference in the Standard Patient Evaluation of Eye Dryness (SPEED) scores between the two groups [SMD -0.16 (95% CI, -0.41 to 0.10)] but a significant increase in Non-Invasive Tear Break-Up Time (NIBUT) scores in the IPL group (SMD, 0.90; 95% CI, 0.40-1.40). To conclude, the results of the present study did not provide any conclusive evidence for the efficacy of IPL therapy in the management of MGD. The analysis indicated that IPL therapy may result in an improvement of objective NIBUT scores but has no effect on subjective SPEED scores. Given the limited number of studies performed to date, there is a requirement for more well-designed prospective RCTs with a larger sample size to provide further evidence on the efficacy of IPL therapy.

Infrared meibography allows detection of dimensional changes in meibomian glands following intranasal neurostimulation

PURPOSE

Patients with dry eye disease (DED) may suffer from decreased tear break-up time due to meibomian gland (MG) dysfunction. Infrared meibography (IR Meibography) uses infrared wavelength light to visualize meibomian glands in vivo. We aimed to explore the feasibility of using serial IR Meibography imaging to assess morphological changes in MGs as an indirect measure of functionality, following intranasal neurostimulation (ITN).

METHODS

Fifteen DED subjects were prospectively enrolled in a single-center, single-arm study. Changes in MGs were captured using IR meibography (RTVUE-XR, Optovue, Inc. Fremont, CA, USA) on the lower eyelids before and after 3 min of ITN (TrueTear®, Allergan, Dublin, Ireland) use that delivers a microcurrent to sensory neurons of the nasal cavity. The same MGs were selected pre- and post-stimulation, and MG area and perimeter were analyzed by two masked observers.

RESULTS

Mean (±SD) pre- and post-stimulation MG areas were 2,187.60 ± 635.88 μm² and 1,933.20 ± 538.55 μm², respectively. The mean change in area, 254.49 μm², representing an 11.6% reduction following ITN use, was statistically significant (p = 0.001). Mean (±SD) pre- and post-stimulation MG perimeters were 235.9 ± 51.38 μm and 222.2 ± 47.72 μm, respectively. The mean change in perimeter, 13.7 μm, representing a 5.81% reduction following ITN use, was statistically significant (p = 0.012).

CONCLUSIONS

Our study shows that IR meibography can be used to detect immediate changes in gland area and perimeter, an indirect measure of MG activity following intervention by ITN.

High Frequency Electrotherapy for the Treatment of Meibomian Gland Dysfunction

PURPOSE

To test the safety and efficacy of high frequency electrotherapy (ET) on the clinical signs and symptoms of patients affected by dry eye and meibomian gland dysfunction (MGD).

METHODS

Twenty-five patients affected by MGD were enrolled. Quantum Molecular Resonance ET was administered by means of the Rexon-Eye device 4 times, once per week for 4 weeks. Patients were reexamined 1 month after the last treatment. The primary endpoint was reduction in corneal fluorescein staining. Additional endpoints were tear break-up time, Ocular Surface Disease Index score, meibomian gland secretion score, and the number of expressible meibomian glands. Safety endpoints were Logarithm of the Minimum Angle of Resolution (LogMar) best spectacle-corrected visual acuity and intraocular pressure.

RESULTS

Corneal fluorescein staining improved by 62.5% (P < 0.0001), tear breakup time increased by 30.9% (P < 0.0001), and the Ocular Surface Disease Index score improved by 37% (P < 0.001). The meibum quality and the number of expressible meibomian glands also increased (35.7% and 12%, P < 0.001 and P < 0.0001, respectively). Schirmer test scores increased after treatment by 16.5% (P = 0.01). No adverse events were observed.

CONCLUSIONS

Quantum Molecular Resonance ET appears to be safe and significantly reduces symptoms and signs associated with MGD. It may have a relevant role in the treatment of evaporative dry eye disease.

Management of meibomian gland dysfunction: a review

Meibomian gland dysfunction is the leading cause of evaporative dry eye disease and is one of the most common conditions encountered by eye care providers. The disorder is characterized by obstruction of the meibomian gland terminal ducts and/or changes in their glandular secretion, resulting in changes in tear film stability, inflammation, and symptoms of irritation. There is no gold standard treatment for meibomian gland dysfunction, but rather a diversity of options. Conservative measures include warm compresses and lid hygiene, but there is growing interest and need for medical treatments and procedures. Potential medical treatments include antibiotics, nonsteroidal and steroidal anti-inflammatory agents, essential fatty acid supplementation, hormone therapy, and control of Demodex infestation. Procedures include intraductal meibomian gland probing, the use of electronic heating devices, intense pulsed light therapy, and intranasal neurostimulation. We provide an update on meibomian gland dysfunction treatments based on recent studies.

Chronic Electrical Stimulation for Tear Secretion: Lacrimal vs. anterior ethmoid nerve

PURPOSE

To evaluate and compare the effect of lacrimal nerve stimulation (LNS) and anterior ethmoid nerve stimulation (AENS) on aqueous tear secretion, and tissue condition following chronic implantation.

METHODS

A neurostimulator was implanted in rabbits adjacent to the (1) lacrimal nerve, and (2) anterior ethmoid nerve. Tear volume was measured with Schirmer test strips after stimulation (2.3-2.8 mA pulses at 30 Hz for 3-5 min), and scores were compared to sham stimulation. Lacrimal gland and nasal septal tissue were evaluated histologically after chronic stimulation (2 weeks-7 months).

RESULTS

LNS increases tear volume by 32% above sham (p < 0.05, n = 5), compared with 133% for AENS (p ≤ 0.01, n = 6). AENS also significantly increases tear secretion in the fellow, non-stimulated eye (p ≤ 0.01, n = 6), as expected from the tearing reflex pathway. Histologically, chronic LNS is well tolerated by surrounding tissues while chronic AENS results in nasal mucosal fibrosis and implant extrusion within 3 weeks.

CONCLUSIONS

AENS is significantly more effective than LNS at enhancing aqueous tear secretion, including the fellow eye. The lacrimal implant is well tolerated, while the nasal implant requires further design optimization to improve tolerability.

Quantum Dots in Ophthalmology: A Literature Review

Purpose: The aim of the current review was to summarize the current applications, the latest advances and importantly, highlight research gaps in the use of quantum dots in the eye. Quantum dots are nanoscale semiconductor crystals with characteristic size and tunable optical properties, which deliver bright and stable fluorescence suitable for bioimaging and labelling. Methods: A systematic search was conducted following the PRISMA guidelines. This review systematically searched published data to summarize the characteristics and applications of quantum dots in ophthalmology. Two hundred and eighty published articles were initially selected for this review following searches using the criteria quantum dots AND nanoparticles AND ophthalmology in the databases PubMed, MEDLINE, Scopus, Embase and Web of Science. Results: After duplicates were removed, a total of 22 eligible articles were included for the review. Quantum dots potentially provide a range of diagnostic and therapeutic applications in ophthalmology. Quantum dots offer visible and near-infrared emission, which is highly desirable for bioimaging, due to reduced light scattering and low tissue absorption. Their applications include in vivo bioimaging, labelling of cells and tissues, delivery of genes or drugs and as antimicrobial composites. Conclusion: Quantum dots have been used in ophthalmology for bioimaging, electrical stimulation and tracking of gene/stems cells, and ocular lymphatics. However, there is no detailed description of their desirable characteristics for use in ophthalmology, and there is limited information about their cytotoxicity to ocular cells and tissues.

Neurostimulation for tear production

PURPOSE OF REVIEW

Dry eye disease (DED) is a chronic multifactorial disease that affects millions of people worldwide. Despite ongoing research, treatment for DED remains a challenge. Neurostimulation for tear production is a rapidly evolving field that culminated in the development of the intranasal tear neurostimulator (ITN). In this article, we review the neuroanatomy and pathophysiology of tear production and the evolution of neurostimulation for the treatment of DED.

RECENT FINDINGS

The ITN was approved for commercial use in April 2017. This innovation stemmed from the success of lacrimal nerve and anterior ethmoid nerve stimulation animal studies. Since then, numerous pilot studies and multicenter randomized controlled trials demonstrate increased aqueous tear production, improved DED-related symptoms, and device safety. Recent studies also report the positive effects of intranasal stimulation on mucin and lipid secretion.

SUMMARY

Neurostimulation for enhanced tear production is a promising new treatment option for DED. Stimulation of the lacrimal nerve and anterior ethmoid nerve both effectively increase tear volume. The ITN is a noninvasive device that effectively increases aqueous tear volume and may improve tear composition, including mucin and lipid concentrations. Further studies are needed to determine proper patient selection and the long-term efficacy of neurostimulation for DED.

A comparative study of the quality of non-stimulated and stimulated tears in normal eye male subjects using the tear ferning test

PURPOSE

To evaluate and compare the tear ferning patterns of non-stimulated and stimulated tears in normal eye male subjects using the tear ferning test.

METHODS

Thirty-five male subjects aged 20-38 years with normal eyes were enrolled in the study. Subjects with dry eye or with a risk factor for eye dryness (eg, recent ocular surgery, contact-lens wearers, smokers, anemic, diabetes, and thyroid gland problems) were excluded from the study. Dry eye subjects were excluded based on the ocular surface diseases index scores, non-invasive tear break-up time, and tear meniscus height measurements from the right and left eyes. A tear sample was collected from both eyes in each subject to perform the tear ferning test for non-stimulated tears. After 10 mins, the tears were stimulated using a Schirmer strip, a tear sample was collected from both eyes in each participant, the tear ferning test was performed, and the ferns were graded based on the five-point tear ferning grading scale.

RESULTS

The average tear ferning grade [median (interquartile range)] for non-stimulated tears from the right and left eyes was 0.60 (1.25) and 0.50 (1.31), respectively. For stimulated tears, the average tear ferning grade from the right and left eyes was 0.50 (1.05) and 0.75 (1.25), respectively. There was no significant difference in the tear ferning grades obtained from non-stimulated and stimulated tears (Wilcoxon test, P>0.05).

CONCLUSION

This study found no significant difference in the tear ferning patterns obtained from non-stimulated and stimulated tears, or between the tear ferning patterns in the tears collected from the right and left eyes before and after stimulating tears. It seems that there were no changes in the chemical composition of tears before and after stimulation, possibly due to the steady concentration of electrolytes and lipids within the tear film for both non-stimulated and stimulated tears.

Advances in Functional Restoration of the Lacrimal Glands

The lacrimal glands produce tears to support a healthy homeostatic environment on the ocular surface. The lacrimal gland dysfunction characteristic of dry eye disease causes ocular discomfort and visual disturbances and in severe cases can result in a loss of vision. The demand for adequate restoration of lacrimal gland function has been intensified due to advances in stem cell biology, developmental biology, and bioengineering technologies. In addition to conventional therapies, including artificial tears, tear alternatives (such as autologous serum eye drops) and salivary gland transplantation, a regenerative medicine approach has been identified as a novel strategy to restore the function of the lacrimal gland. Recent studies have demonstrated the potential of progenitor cell injection therapy to repair the tissue of the lacrimal glands. A current three-dimensional (3D) tissue engineering technique has been shown to regenerate a secretory gland structure by reproducing reciprocal epithelial-mesenchymal interactions during ontogenesis in vitro and in vivo. A novel direct reprogramming method has suggested a possibility to induce markers in the lacrimal gland developmental process from human pluripotent stem cells. The development of this method is supported by advances in our understanding of gene expression and regulatory networks involved in the development and differentiation of the lacrimal glands. Engineering science has proposed a medical device to stimulate tearing and a bio-hybrid scaffold to reconstruct the 3D lacrimal gland structure. In this review, we will summarize recent bioengineering advances in lacrimal gland regeneration toward the functional restoration of the lacrimal glands as a future dry eye therapy.

Tivanisiran, a novel siRNA for the treatment of dry eye disease

INTRODUCTION

Dry eye disease (DED) is characterized by an alteration of the tear film with ocular inflammation and neurosensory abnormalities. The main clinical signs of this condition are tear instability and ocular damage. Although DED has gained significant attention in the past few years, limited prescription treatment options are available for patients. Areas covered: The current manuscript summarizes the pre-clinical and clinical development of tivanisiran, a novel small interfering oligonucleotide of RNA (siRNA) used for the treatment of DED. Tivanisiran was designed to silence Transient Receptor Potential Vanilloid 1 (TRPV1); herein the chemistry and mechanism of action of this new compound is also described. Expert opinion: Drugs currently on the market mostly target the inflammatory component of the disease and show only partial efficacy. New compounds addressing other aspects of the disease would provide significant advantages and contribute to a more personalized treatment of the disease. Tivanisiran has been designed to reduce ocular discomfort and pain, and was shown to improve ocular hyperemia and tear quality in human and animal models. Consequently, if the results of the ongoing and future clinical trials meet their study endpoints, tivanisiran could be submitted to obtain approval for the treatment of DED.

[Novel current and future therapy options for treatment of dry eye disease]

Dry eye disease was redefined by the dry eye workshop (DEWS II) in May 2017. According to the new definition "dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film and accompanied by ocular symptoms". The current definition encompasses etiological factors, such as instability and hyperosmolarity of the tear film, ocular surface inflammation and damage as well as a new aspect compared to the former definition, neurosensory abnormalities. Recent and future therapeutic options for dry eye focus on treatment of the aforementioned pathogenetic events. New tear substitutes, medications and devices to stimulate tear production, innovative anti-inflammatory treatment, medications to influence corneal innervation and new methods for treatment of Meibomian gland dysfunction are already available or will be available in the near future.