Visualization of conventional outflow tissue responses to netarsudil in living mouse eyes

A Histomorphometric and Computational Investigation of the Stabilizing Role of Pectinate Ligaments in the Aqueous Outflow Pathway

Murine models are commonly used to study glaucoma, the leading cause of irreversible blindness. Glaucoma is associated with elevated intra-ocular pressure (IOP), which is regulated by the tissues of the aqueous outflow pathway. In particular, pectinate ligaments (PLs) connect the iris and trabecular meshwork (TM) at the anterior chamber angle, with an unknown role in maintenance of the biomechanical stability of the aqueous outflow pathway, thus motivating this study. We conducted histomorphometric analysis and optical coherence tomography-based finite element (FE) modeling on three cohorts of C57BL/6 mice: "young" (2-6 months), "middle-aged" (11-16 months), and "elderly" (25-32 months). We evaluated the age-specific morphology of the outflow pathway tissues. Further, because of the known pressure-dependent Schlemm's canal (SC) narrowing, we assessed the dependence of the SC lumen area on varying IOPs in age-specific FE models over a physiological range of TM/PL stiffness values. We found age-dependent changes in morphology of outflow tissues; notably, the PLs were more developed in older mice compared to younger ones. In addition, FE modeling demonstrated that murine SC patency is highly dependent on the presence of PLs and that increased IOP caused SC collapse only with sufficiently low TM/PL stiffness values. Moreover, the elderly model showed more susceptibility to SC collapse compared to the younger models. In conclusion, our study elucidated the previously unexplored role of PLs in the aqueous outflow pathway, indicating their function in supporting TM and SC under elevated IOP.

Characterization of Forced Degradation Products of Netarsudil: Optimization and Validation of a Stability-Indicating RP-HPLC Method for Simultaneous Quantification of Process-Related Impurities

Objectives

The aim of this study is to examine resolution, identification, and characterization of forced degradation products of netarsudil by liquid chromatography-tandem mass spectrometry by validating a simple and sensitive high-performance liquid chromatography method for the resolution, identification, and quantification of two process-related impurities in netarsudil.

Materials and Methods

Chromatographic separation was accomplished on a ZORBAX Eclipse XDB C18 (250 x 4.6 mm; 5 µ id) column at room temperature as the stationary phase and 257 nm as the detector wavelength with the mobile phase consisting of acetonitrile, methanol, and pH 4.6 phosphate buffer in 45:35:20 (v/v) at 1.0 mL/min flow rate in isocratic elution.

Results

The method reported very sensitive detection limits of 0.008 µg/mL for impurity 1 and 0.003 µg/mL for impurity 1. The method produces a calibration curve linear in the concentration level of 25-200 for netarsudil and 0.025-0.2 µg/mL for impurities. The proposed method gives acceptable results for other validation parameters such as accuracy, precision, ruggedness, and robustness. The drug was subjected to various stress conditions such as acid, base, peroxide, and thermal and ultraviolet light to investigate the stability-indicating ability of the method. Considerable degradation was observed in stress studies, and the degradation products were well resolved from process-related impurities. The characterization of degradation products was performed on the basis of collision-induced dissociation mass spectral data, and the possible structures of the six degradation compounds of netarsudil were proposed.

Conclusion

The outcomes of other validation studies were likewise satisfactory and proven adequate for the regular analysis of netarsudil and its process-related impurities in bulk drug and pharmaceutical dosage forms and can also be applied for the evaluation of the stress degradation mechanism of netarsudil.

Aging and intraocular pressure homeostasis in mice

Age and elevated intraocular pressure (IOP) are the two primary risk factors for glaucoma, an optic neuropathy that is the leading cause of irreversible blindness. In most people, IOP is tightly regulated over a lifetime by the conventional outflow tissues. However, the mechanistic contributions of age to conventional outflow dysregulation, elevated IOP and glaucoma are unknown. To address this gap in knowledge, we studied how age affects the morphology, biomechanical properties and function of conventional outflow tissues in C57BL/6 mice, which have an outflow system similar to humans. As reported in humans, we observed that IOP in mice was maintained within a tight range over their lifespan. Remarkably, despite a constellation of age-related changes to the conventional outflow tissues that would be expected to hinder aqueous drainage and impair homeostatic function (decreased cellularity, increased pigment accumulation, increased cellular senescence and increased stiffness), outflow facility, a measure of conventional outflow tissue fluid conductivity, was stable with age. We conclude that the murine conventional outflow system has significant functional reserve in healthy eyes. However, these age-related changes, when combined with other underlying factors, such as genetic susceptibility, are expected to increase risk for ocular hypertension and glaucoma.

Rho Kinase Inhibitors: Strategies in Glaucoma Treatment in Older Adults

Glaucoma is a leading cause of irreversible blindness which preferentially affects older individuals. No medications or therapies which are currently in our arsenal actually treat glaucoma itself. We know that intraocular pressure (IOP) is currently the only modifiable risk factor for glaucoma. The primary treatments for glaucoma include medications, laser therapies, and surgical therapies. The Rho kinase inhibitors are the newest class of medications currently on the market and in development for topical IOP-lowering therapy. Studies have shown their ability to lower eye pressure individually and in combination with other medications. Their ability to potentially provide neuroprotective effects for disease modification also gives this class exciting potential for glaucoma treatment.

A Histomorphometric and Computational Investigation of the Stabilizing Role of Pectinate Ligaments in the Aqueous Outflow Pathway

Murine models are commonly used to study glaucoma, the leading cause of irreversible blindness. Glaucoma is associated with elevated intraocular pressure (IOP), which is regulated by the tissues of the aqueous outflow pathway. In particular, pectinate ligaments (PLs) connect the iris and trabecular meshwork (TM) at the anterior chamber angle, with an unknown role in maintenance of the biomechanical stability of the aqueous outflow pathway, thus motivating this study. We conducted histomorphometric analysis and optical coherence tomography-based finite element (FE) modeling on three cohorts of C57BL/6 mice: 'young' (2-6 months), 'middle-aged' (11-16 months), and 'elderly' (25-32 months). We evaluated the age-specific morphology of the outflow pathway tissues. Further, because of the known pressure-dependent Schlemm's canal (SC) narrowing, we assessed the dependence of the SC lumen area to varying IOPs in age-specific FE models over a physiological range of TM/PL stiffness values. We found age-dependent changes in morphology of outflow tissues; notably, the PLs were more developed in older mice compared to younger ones. In addition, FE modeling demonstrated that murine SC patency is highly dependent on the presence of PLs, and that increased IOP caused SC collapse only with sufficiently low TM/PL stiffness values. Moreover, the elderly model showed more susceptibility to SC collapse compared to the younger models. In conclusion, our study elucidated the previously unexplored role of PLs in the aqueous outflow pathway, indicating their function in supporting TM and SC under elevated IOP.

The Role of Rho Kinase Inhibitors in Corneal Diseases

The cornea, as the outermost layer of the eye, plays a crucial role in vision by focusing light onto the retina. Various diseases and injuries can compromise its clarity, leading to impaired vision. This review aims to provide a thorough overview of the pharmacological properties, therapeutic potential and associated risks of Rho-associated protein kinase (ROCK) inhibitors in the management of corneal diseases. The article focuses on four key ROCK inhibitors: Y-27632, fasudil, ripasudil, and netarsudil, providing a comparative examination. Studies supporting the use of ROCK inhibitors highlight their efficacy across diverse corneal conditions. In Fuchs' endothelial corneal dystrophy, studies on the application of Y-27632, ripasudil, and netarsudil demonstrated noteworthy enhancements in corneal clarity, endothelial cell density, and visual acuity. In pseudophakic bullous keratopathy, the injection of Y-27632 together with cultured corneal endothelial cells into the anterior chamber lead to enhanced corneal endothelial cell density and improved visual acuity. Animal models simulating chemical injury to the cornea showed a reduction of neovascularization and epithelial defects after application of fasudil and in a case of iridocorneal endothelial syndrome netarsudil improved corneal edema. Addressing safety considerations, netarsudil and ripasudil, both clinically approved, exhibit adverse events such as conjunctival hyperemia, conjunctival hemorrhage, cornea verticillata, conjunctivitis, and blepharitis. Monitoring patients during treatment becomes crucial to balancing the potential therapeutic benefits with these associated risks. In conclusion, ROCK inhibitors, particularly netarsudil and ripasudil, offer promise in managing corneal diseases. The comparative analysis of their pharmacological properties and studies supporting their efficacy underscore their potential therapeutic significance. However, ongoing research is paramount to comprehensively understand their safety profiles and long-term outcomes in diverse corneal conditions, guiding their optimal application in clinical practice.

Rho Kinase (ROCK) Inhibitors for the Treatment of Glaucoma

Glaucoma is the most common cause of irreversible blindness worldwide. It is characterized by progressive optic nerve degeneration and loss of visual field. Pathological increased intraocular pressure is its main modifiable risk factor. Rho kinase inhibitors are developed as a new class of glaucoma medication that increases outflow facility from the conventional aqueous humor outflow pathway. Additionally, they also have neuroprotective and anti-scarring effects that can might increase the success rate of glaucoma filtration surgery. This review aims to summarize the current concept of Rho kinase inhibitors in the treatment of glaucoma from beach to bedside.

Aging and intraocular pressure homeostasis in mice

Age and elevated intraocular pressure (IOP) are the two primary risk factors for glaucoma, an optic neuropathy that is the leading cause of irreversible blindness. In most people, IOP is tightly regulated over a lifetime by the conventional outflow tissues. However, the mechanistic contributions of age to conventional outflow dysregulation, elevated IOP and glaucoma are unknown. To address this gap in knowledge, we studied how age affects the morphology, biomechanical properties and function of conventional outflow tissues in C57BL/6 mice, which have an outflow system similar to humans. As reported in humans, we observed that IOP in mice was maintained within a tight range over their lifespan. Remarkably, despite a constellation of age-related changes to the conventional outflow tissues that would be expected to hinder aqueous drainage and impair homeostatic function (decreased cellularity, increased pigment accumulation, increased cellular senescence and increased stiffness), outflow facility, a measure of conventional outflow tissue fluid conductivity, was stable with age. We conclude that the murine conventional outflow system has significant functional reserve in healthy eyes. However, these age-related changes, when combined with other underlying factors, such as genetic susceptibility, are expected to increase risk for ocular hypertension and glaucoma.

Rho-Kinase Inhibitors as Emerging Targets for Glaucoma Therapy

Glaucoma, the leading cause of irreversible blindness worldwide, is a chronic and progressive optic neuropathy characterized by damage to the optic and retinal nerve fiber layers, which can lead to permanent loss of peripheral or central vision. Reduction of intraocular pressure (IOP) is the only known modifiable risk factor for preventing and treating glaucoma. Rho kinase (ROCK) inhibitors are a new class of glaucoma drugs with a novel mechanism of action and good safety profile. They exert neuroprotective effects, act on the trabecular tissue, increase the outflow of aqueous humor, and reduce intraocular pressure. However, they also cause local adverse reactions, including common conjunctival congestion and subconjunctival bleeding; however, most are self-limiting and temporary. Netarsudil (0.02%), a ROCK inhibitor, relaxes the trabecular meshwork, increases the outflow of aqueous humor, reduces scleral venous pressure, and directly decreases IOP. Conjunctival congestion can be reduced if netarsudil is administered at night. The combination of these medications is always more effective than the single drug. Ripasudil (0.4%), another ROCK inhibitor, also lowers IOP; however, conjunctival hyperemia is the most common adverse drug reaction. The purpose of this review is to summarize the effects and adverse reactions of ROCK inhibitors in the experimental trial stage and in clinical treatment in recent years, providing suggestions for future clinical drug use, and research and development to reduce the side effects of these drugs, maximize the potential for reducing IOP, and improve the therapeutic effect.

Phase 3 Clinical Trial Comparing the Safety and Efficacy of Netarsudil to Ripasudil in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension: Japan Rho Kinase Elevated Intraocular Pressure Treatment Trial (J-ROCKET)

INTRODUCTION

A clinical trial evaluated ocular hypotensive efficacy and safety of netarsudil 0.02% once daily (QD) relative to ripasudil 0.4% twice daily (BID).

METHODS

This was a single-masked, randomized, phase 3, superiority study. Japanese patients were randomized to either the netarsudil 0.02% group or the ripasudil 0.4% group in a 1:1 ratio and treated for 4 weeks. The primary efficacy variable was mean diurnal intraocular pressure (IOP) (average of diurnal time points at 09:00, 11:00, and 16:00) at Week 4.

RESULTS

A total of 245 patients were included in the primary analysis. At Week 4, least squares (LS) mean of diurnal IOP adjusted for baseline was 15.96 and 17.71 mmHg in the netarsudil 0.02% and ripasudil 0.4% groups, respectively, demonstrating the superiority of netarsudil 0.02% QD over ripasudil 0.4% BID by a margin of - 1.74 mmHg (p < 0.0001). Mean reduction from baseline in mean diurnal IOP at Week 4 was 4.65 and 2.98 mmHg, respectively. Adverse events (AEs) occurred less frequently in netarsudil 0.02% than in ripasudil 0.4%, with the incidence of ocular AEs being 59.8% and 66.7%, respectively. The most frequently reported AE was conjunctival hyperemia in both groups, with an incidence of 54.9% and 62.6%, respectively. No serious eye-related AEs were reported.

CONCLUSION

Netarsudil ophthalmic solution 0.02% dosed QD (p.m.) was well tolerated and more effective in reducing IOP than ripasudil ophthalmic solution 0.4% dosed BID. Netarsudil 0.02% QD may become an important option for the treatment of Japanese patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT).

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT04620135.

Pressure Clamping During Ocular Perfusions Drives Nitric Oxide-Mediated Washout

Purpose

The aim of this study was to test the hypothesis that nitric oxide (NO) mediates a pressure-dependent, negative feedback loop that maintains conventional outflow homeostasis and thus IOP. If true, holding pressure during ocular perfusions will result in uncontrolled production of NO, hyper-relaxation of the trabecular meshwork, and washout.

Methods

Paired porcine eyes were perfused at constant pressure of 15 mm Hg. After 1 hour acclimatization, one eye was exchanged with N5-[imino(nitroamino)methyl]-L-ornithine, methyl ester, monohydrochloride (L-NAME) (50 µm) and the contralateral eye with DBG, and perfused for 3 hours. In a separate group, one eye was exchanged with DETA-NO (100 nM) and the other with DBG and perfused for 30 minutes. Changes in conventional outflow tissue function and morphology were monitored.

Results

Control eyes exhibited a washout rate of 15% (P = 0.0026), whereas eyes perfused with L-NAME showed a 10% decrease in outflow facility from baseline over 3 hours (P < 0.01); with nitrite levels in effluent positively correlating with time and facility. Compared with L-NAME-treated eyes, significant morphological changes in control eyes included increased distal vessel size, number of giant vacuoles, and juxtacanalicular tissue separation from the angular aqueous plexi (P < 0.05). For 30-minute perfusions, control eyes showed a washout rate of 11% (P = 0.075), whereas DETA-NO-treated eyes showed an increased washout rate of 33% from baseline (P < 0.005). Compared with control eyes, significant morphological changes in DETA-NO-treated eyes also included increased distal vessel size, number of giant vacuoles and juxtacanalicular tissue separation (P < 0.05).

Conclusions

Uncontrolled NO production is responsible for washout during perfusions of nonhuman eyes where pressure is clamped.

Rho Kinase Inhibitor AR-12286 Reverses Steroid-Induced Changes in Intraocular Pressure, Effective Filtration Areas, and Morphology in Mouse Eyes

Purpose

We investigated mechanisms of reduction of intraocular pressure (IOP) by Rho kinase inhibitor AR-12286 in steroid-induced ocular hypertension (SIOH).

Methods

C57BL/6 mice (N = 56) were randomly divided into Saline, dexamethasone (DEX), DEX + AR-12286, and DEX-discontinuation (DEX-DC) groups. IOP was measured weekly during the first four weeks in all groups. Beginning at week 5, the DEX-DC group was followed without treatment until IOP returned to normal, and the other groups were treated as assigned with IOP measured every other day for another week. Fluorescent tracer was injected into the anterior chamber to visualize the outflow pattern in the trabecular meshwork (TM) and TM effective filtration area (EFA) was determined. Radial sections from both high- and low-tracer regions were processed for electron microscopy.

Results

AR-12286 reduced IOP in SIOH mouse eyes in one day (P < 0.01). At the end of week 5, mean IOP in the DEX + AR-12286 group was ∼4 mm Hg lower than DEX group (P < 0.001) and ∼2 mm Hg lower than DEX-DC group (P < 0.05). After one-week AR-12286 treatment (P < 0.05) or five-week DC of DEX (P < 0.01), DEX-induced reduction of EFA was rescued and DEX-induced morphological changes in the TM were partially reversed.

Conclusions

AR-12286 reversed steroid-induced morphological changes in the TM and reduced EFA, which correlated with reduced IOP in SIOH eyes. AR-12286 reduced IOP elevation in SIOH eyes more effectively than discontinuing DEX treatment even when accompanied by continuous DEX treatment. Therefore Rho kinase inhibitors may lower SIOH in patients who rely on steroid treatment.

Netarsudil as an Adjunctive Therapy: Efficacy and Factors Contributing to a Favorable IOP-Lowering Effect

Purpose

The aim of the study is to assess netarsudil's intraocular pressure (IOP)-lowering potential when prescribed as an adjunctive agent, to examine the effect of baseline IOP on patients' response to netarsudil, and to explore patients' characteristics predictive of pronounced responses to netarsudil.

Methods

This is a single-center, multiprovider retrospective cohort study set at Massachusetts Eye and Ear. Patients with a diagnosis of glaucoma or ocular hypertension on netarsudil and at least one other hypotensive agent for glaucoma who had at least one month of follow-up were included. Patients with additional procedures or glaucoma medication changes were excluded. The main outcome measures were IOP reduction, Kaplan-Meier survival analyses, netarsudil responder type, and complication rates.

Results

236 eyes of 236 patients were included. The mean baseline IOP was 19.06 ± 4.6 mmHg on an average of 4 ocular hypotensive medications. 196 (83.1%) patients experienced IOP reduction at the first follow-up visit of 2.84 ± 0.30 mmHg at 55.66 ± 51.89 days. IOP reduction at the second visit among these patients was 3.01 ± 0.44 mmHg at 133.24 ± 77.63 days. After starting netarsudil, 59% had a sustained response (median duration of 315 days), 25% had a robust response (>20% IOP reduction for at least 80% of visits), and 10% had a super response (>20% and >10 mmHg IOP reduction). Netarsudil was effective as an adjunctive therapy across all baseline IOP categories with greater relative IOP reduction in higher baseline IOP groups.

Conclusions

Netarsudil is an effective adjunctive glaucoma therapy. IOP reductions between 2 and 3 mmHg are typical, but a minority had more pronounced and sustained effects (>10 mmHg). Further analysis is needed to assess specific demographic and clinical factors predictive of these robust responses.

Intracameral Injection of AAV-DJ.COMP-ANG1 Reduces the IOP of Mice by Reshaping the Trabecular Outflow Pathway

Purpose

The angiopoietin-1 (ANG1)-TIE signaling pathway orchestrates the development and maintenance of the Schlemm's canal (SC). In this study, we investigated the impact of adeno-associated virus (AAV)-mediated gene therapy with cartilage oligomeric matrix protein-ANG1 (COMP-ANG1) on trabecular outflow pathway.

Methods

Different serotypes of AAVs were compared for transduction specificity and efficiency in the anterior segment. The selected AAVs encoding COMP-ANG1 or ZsGreen1 (control) were delivered into the anterior chambers of wild-type C57BL/6J mice. The IOP and ocular surface were monitored regularly. Ocular perfusion was performed to measure the outflow facility and label flow patterns of the trabecular drainage pathway. Structural features of SC as well as limbal, retinal, and skin vessels were visualized by immunostaining. Ultrastructural changes in the SC and trabecular meshwork were observed under transmission electron microscopy.

Results

AAV-DJ could effectively infect the anterior segment. Intracameral injection of AAV-DJ.COMP-ANG1 lowered IOP in wild-type C57BL/6J mice. No signs of inflammation or angiogenesis were noticed. Four weeks after AAV injection, the conventional outflow facility and effective filtration area were increased significantly (P = 0.005 and P = 0.04, respectively). Consistently, the area of the SC was enlarged (P < 0.001) with increased density of giant vacuoles in the inner wall (P = 0.006). In addition, the SC endothelia lay on a more discontinuous basement membrane (P = 0.046) and a more porous juxtacanalicular tissue (P = 0.005) in the COMP-ANG1 group.

Conclusions

Intracamerally injected AAV-DJ.COMP-ANG1 offers a significant IOP-lowering effect by remodeling the trabecular outflow pathway of mouse eyes.

Segmental outflow dynamics in the trabecular meshwork of living mice

Aqueous humour does not drain uniformly through the trabecular meshwork (TM), but rather follows non-uniform or "segmental" routes. In this study, we examined whether segmental outflow patterns in the TM change over time in living mice and whether such changes are affected by age. Segmental outflow patterns were labelled by constant-pressure infusion of fluorescent tracer microparticles into the anterior chamber of anesthetised C57BL/6J mice at 3 or 8 months of age. Two different tracer colours were infused at separate time points with an interval of Δt = 0, 2, 7 or 14 days. In a separate experiment, one tracer was infused in vivo while the second tracer was infused ex vivo after 2 days. The spatial relationship between the two tracer patterns was analysed using the Pearson's correlation coefficient, r. In 3-month-old mice, there was a time-dependent decay in r, which was near unity at Δt = 0 and near zero at Δt = 14 days. In 8-month-old mice, r remained elevated for 14 days. Segmental outflow patterns measured in young mice ex vivo were not significantly different from those measured in vivo after accounting for the expected changes over 2 days. Therefore, segmental outflow patterns are not static in the TM but redistribute over time, achieving near complete loss of correlation by 2 weeks in young healthy mice. There is an age-related decline in the rate at which segmental outflow patterns redistribute in the TM. Further research is needed to understand the dynamic factors controlling segmental outflow.

Effectiveness of Netarsudil versus Brimonidine in Eyes already Being Treated with Glaucoma Medications at a Single Academic Tertiary Care Practice: A Comparative Study

Background

Rho kinase inhibitors, such as netarsudil, are a relatively new class of medications recently introduced into the market for the treatment of glaucoma, the leading cause of irreversible blindness in the world. Previous clinical trials have studied netarsudil's efficacy when used as a first- or second-line agent but limited studies have investigated its effectiveness in the real world where it is more commonly used as a third, fourth, or fifth agent in combination with other topical medications. Equally important, prior studies have not compared its effectiveness to its peer medications in these settings.

Objective

To compare intraocular pressure (IOP) lowering after initiation of netarsudil or brimonidine therapy in patients with glaucoma using >2 medications for IOP management.

Methods

A chart review of 369 eyes from 279 patients followed at a single academic tertiary practice was performed with an institutional review board waiver of consent to compare IOP lowering after prescription of netarsudil (n = 176) versus brimonidine (n = 193) as a third, fourth, or fifth IOP-lowering agent. Patients were identified by querying the electronic medical record for those with a glaucoma-related diagnosis who were prescribed either medication. Five sequential IOP measurements were obtained to determine the mean change in IOP before and after treatment (ΔIOP = mean IOP_4,5 - mean IOP_1,2,3). A multilevel linear mixed-effects model assessed the influence of medication (independent variable) on ΔIOP (dependent variable). Additional independent variables of interest included the number of glaucoma medications at baseline, age, sex, glaucoma type and severity, race, and pretreatment IOP. Bootstrap analysis was performed to remove sampling bias and confirm mixed-effects model findings. Kaplan-Meier survival analysis evaluated the probability of requiring additional intervention within 3 years following the date of medication prescription.

Results

The unadjusted mean (SD) ΔIOP for netarsudil and brimonidine was -2.20 (4.11) mm Hg and -2.21 (3.25) mm Hg, respectively (P = 0.484). The adjusted linear mixed-effects models and bootstrap analysis demonstrated that there was no statistical difference in IOP-lowering effectiveness between the medications. Netarsudil and brimonidine failed to adequately control IOP at similar rates with 42% and 47% probabilities of survival respectively by the 3-year follow-up (P = 0.520).

Conclusions

When escalating pharmacologic therapy, the IOP-lowering effect of netarsudil appeared to be similar to that produced by brimonidine. (Curr Ther Res Clin Exp. 2023; 84:XXX-XXX).

Aqueous column changes in the episcleral veins after the instillation of ripasudil versus latanoprost: a randomized, double-blind, crossover clinical trial

To investigate whether the topical administration of ripasudil ophthalmic solution enhances aqueous outflow in the episcleral vein of the human eye. Two-sequence, prospective, randomized, double-blind, crossover trial. Sixteen eyes of 16 healthy participants were recruited in this study. Participants were randomized into one of the two crossover sequences to the instillation of ripasudil or the control drug, latanoprost, followed by a washout period of more than 2 days, and crossed over to the alternative instillation. The aqueous columns in the episcleral veins were recorded using a video capture system connected to a slit-light microscope (hemoglobin video imaging) before and 2 and 8 h after the instillation. Comparisons between ripasudil and latanoprost for the changes of the aqueous column width after the instillation. Two hours after the instillation, the ripasudil group had significantly greater dilation of the aqueous column width than the latanoprost group. Eight hours after the instillation, the ripasudil group had significantly greater dilation of the aqueous column width than the latanoprost group. Hemoglobin video imaging revealed that the topical administration of ripasudil ophthalmic solution enhanced aqueous outflow in the episcleral vein of the human eye.

Remodeling of the Lamina Cribrosa: Mechanisms and Potential Therapeutic Approaches for Glaucoma

Glaucomatous optic neuropathy is the leading cause of irreversible blindness in the world. The chronic disease is characterized by optic nerve degeneration and vision field loss. The reduction of intraocular pressure remains the only proven glaucoma treatment, but it does not prevent further neurodegeneration. There are three major classes of cells in the human optic nerve head (ONH): lamina cribrosa (LC) cells, glial cells, and scleral fibroblasts. These cells provide support for the LC which is essential to maintain healthy retinal ganglion cell (RGC) axons. All these cells demonstrate responses to glaucomatous conditions through extracellular matrix remodeling. Therefore, investigations into alternative therapies that alter the characteristic remodeling response of the ONH to enhance the survival of RGC axons are prevalent. Understanding major remodeling pathways in the ONH may be key to developing targeted therapies that reduce deleterious remodeling.

Effects of Netarsudil-Family Rho Kinase Inhibitors on Human Trabecular Meshwork Cell Contractility and Actin Remodeling Using a Bioengineered ECM Hydrogel

Interactions between trabecular meshwork (TM) cells and their extracellular matrix (ECM) are critical for normal outflow function in the healthy eye. Multifactorial dysregulation of the TM is the principal cause of elevated intraocular pressure that is strongly associated with glaucomatous vision loss. Key characteristics of the diseased TM are pathologic contraction and actin stress fiber assembly, contributing to overall tissue stiffening. Among first-line glaucoma medications, the Rho-associated kinase inhibitor (ROCKi) netarsudil is known to directly target the stiffened TM to improve outflow function via tissue relaxation involving focal adhesion and actin stress fiber disassembly. Yet, no in vitro studies have explored the effect of netarsudil on human TM (HTM) cell contractility and actin remodeling in a 3D ECM environment. Here, we use our bioengineered HTM cell-encapsulated ECM hydrogel to investigate the efficacy of different netarsudil-family ROCKi compounds on reversing pathologic contraction and actin stress fibers. Netarsudil and all related experimental ROCKi compounds exhibited significant ROCK1/2 inhibitory and focal adhesion disruption activities. Furthermore, all ROCKi compounds displayed potent contraction-reversing effects on HTM hydrogels upon glaucomatous induction in a dose-dependent manner, relatively consistent with their biochemical/cellular inhibitory activities. At their tailored EC50 levels, netarsudil-family ROCKi compounds exhibited distinct effect signatures of reversing pathologic HTM hydrogel contraction and actin stress fibers, independent of the cell strain used. Netarsudil outperformed the experimental ROCKi compounds in support of its clinical status. In contrast, at uniform EC50-levels using netarsudil as reference, all ROCKi compounds performed similarly. Collectively, our data suggest that netarsudil exhibits high potency to rescue HTM cell pathobiology in a tissue-mimetic 3D ECM microenvironment, solidifying the utility of our bioengineered hydrogel model as a viable screening platform to further our understanding of TM pathophysiology in glaucoma.

Response to netarsudil in goniotomy-treated eyes and goniotomy-naïve eyes: a pilot study

PURPOSE

To compare the intraocular pressure (IOP)-lowering effects of netarsudil on goniotomy-treated eyes versus goniotomy-naïve control eyes.

METHODS

Retrospective cohort study of 70 eyes from 49 adult glaucoma patients treated with netarsudil. Thirty-five eyes received sectoral goniotomy using Kahook Dual Blade (KDB) combined with cataract surgery with minimum of 3 months prior to netarsudil treatment. Thirty-five eyes in the control cohort received only cataract surgery prior to netarsudil. Primary outcome was treatment success, defined as ≥ 20% decrease in IOP at minimum 1 month follow-up. Secondary outcome measures included percent of IOP reduction, adverse effects of medication, medication discontinuation rate, and relationship between KDB goniotomy response and netarsudil response.

RESULTS

Eighty-three percent of KDB-treated eyes achieved netarsudil treatment success compared to 54% of control eyes (P = .012). IOP reduction was 30.3 ± 16.2% (IQR 21-38%) in KDB-treated eyes and 19.4 ± 12.4% (IQR 9.2-30.8) in control eyes (P = .007). History of prior KDB increased the likelihood of success to netarsudil treatment compared to eyes without prior KDB, regardless of surgical response to KDB (odds ratio 4.51, 95% CI 1.34-15.14, P = .015). The overall rate of adverse effects of netarsudil was 42%, most commonly reported as conjunctival hyperemia, allergy, and blurred vision.

CONCLUSIONS

Netarsudil had a greater IOP-lowering effect in eyes treated with prior goniotomy and may serve as a promising adjunctive ocular hypotensive agent to further reduce IOP in eyes with prior goniotomy.

Relationships between Intraocular Pressure, Effective Filtration Area, and Morphological Changes in the Trabecular Meshwork of Steroid-Induced Ocular Hypertensive Mouse Eyes

We investigated whether an inverse relationship exists between intraocular pressure (IOP) and effective filtration area (EFA) in the trabecular meshwork (TM) in a steroid-induced ocular hypertensive (SIOH) mouse model and the morphological changes associated with the reduction of EFA. C57BL/6 mice (n = 15 per group) received either 0.1% dexamethasone (DEX) or saline eye drops twice daily for five weeks. IOP was measured weekly. Fluorescent tracers were injected into the anterior chamber to label EFA at the endpoint. Injected eyes were fixed and processed for confocal microscopy. EFA in the TM was analyzed. Light and electron microscopy were performed in high- and low-tracer regions of six eyes per group. The mean IOP was ~4 mm Hg higher in DEX-treated than saline-treated control eyes (p < 0.001) at the endpoint. EFA was reduced in DEX-treated eyes compared to controls (p < 0.01) and negatively correlated with IOP (R² = 0.38, p = 0.002). Reduced thickness of juxtacanalicular tissue (JCT) and increased abnormal extracellular matrix in the JCT were found to be associated with reduced EFA. Our data confirm the inverse relationship between EFA and IOP, suggesting that morphological changes in the JCT contribute to the reduction of EFA, thus elevating IOP in SIOH mouse eyes.

Open-source deep learning-based automatic segmentation of mouse Schlemm's canal in optical coherence tomography images

The purpose of this study was to develop an automatic deep learning-based approach and corresponding free, open-source software to perform segmentation of the Schlemm's canal (SC) lumen in optical coherence tomography (OCT) scans of living mouse eyes. A novel convolutional neural network (CNN) for semantic segmentation grounded in a U-Net architecture was developed by incorporating a late fusion scheme, multi-scale input image pyramid, dilated residual convolution blocks, and attention-gating. 163 pairs of intensity and speckle variance (SV) OCT B-scans acquired from 32 living mouse eyes were used for training, validation, and testing of this CNN model for segmentation of the SC lumen. The proposed model achieved a mean Dice Similarity Coefficient (DSC) of 0.694 ± 0.256 and median DSC of 0.791, while manual segmentation performed by a second expert grader achieved a mean and median DSC of 0.713 ± 0.209 and 0.763, respectively. This work presents the first automatic method for segmentation of the SC lumen in OCT images of living mouse eyes. The performance of the proposed model is comparable to the performance of a second human grader. Open-source automatic software for segmentation of the SC lumen is expected to accelerate experiments for studying treatment efficacy of new drugs affecting intraocular pressure and related diseases such as glaucoma, which present as changes in the SC area.

Current situation and progress of drugs for reducing intraocular pressure

Glaucoma, the most common cause of irreversible blindness worldwide, usually causes characteristic optic nerve damage. Pathological intraocular pressure (IOP) elevation is a major risk factor. Drug reduction of IOP is the preferred treatment for clinicians because it can delay the progression of disease. However, the traditional IOP-lowering drugs currently used by patients may be poorly tolerated. Therefore, in recent years, some new drugs have been put into clinical application or in clinical phase I–III studies. They have a better IOP-lowering effect and fewer adverse reactions. Because glaucoma is a chronic disease, drugs need to be administered continuously for a long time. For patients, good compliance and high drug bioavailability have a positive effect on the prognosis of the disease. Therefore, clinicians and scientists have developed drug delivery systems to solve this complex problem. In addition, natural compounds and dietary supplements have a good effect of reducing IOP, and they can also protect the optic nerve through antioxidant action. We summarize the current traditional drugs, new drugs, sustained-release drug delivery systems, and complementary drugs and outline the mechanism of action and clinical effects of these drugs on glaucoma and their recent advances.

Safety and efficacy of topically administered netarsudil-latanoprost fixed dose combination (FDC; Rocklatan™) in normal and glaucomatous dogs with ADAMTS10-open-angle glaucoma (ADAMTS10-OAG)

OBJECTIVE

The aim of the study was to evaluate safety and efficacy of topically administered 0.02% netarsudil-0.005% latanoprost fixed-dose combination (FDC) (Rocklatan™; Aerie Pharmaceutical) in normal and glaucomatous dogs with ADAMTS10-open-angle glaucoma (ADAMTS10-OAG).

ANIMALS STUDIED

Five normal and five glaucomatous beagle dogs with ADAMTS10-OAG were the study animals.

PROCEDURES

In each dog, left (OS) or right eye (OD) was randomly selected for netarsudil-latanoprost FDC treatment. Contralateral eyes served as latanoprost-treated controls. The study was divided into four consecutive study periods: following a 4-day baseline period, two sequential 8-day study periods followed with once daily (q24h) and twice daily (q12h) treatments and ending with a washout period. Efficacy was measured by diurnal intraocular pressure (IOP) and pupil diameter. Safety was assessed by routine ophthalmic examination, gonioscopy, and pachymetry. Differences in least square means of quantitative outcome measures were compared between FDC and latanoprost treatments by using the linear Gaussian model.

RESULTS

Baseline IOPs were 13.6 ± 0.7 mmHg (mean ± SEM) in normal and 28.3 ± 1.4 mmHg in OAG-affected dogs. There was a significant decrease in mean diurnal IOP following FDC administration in both normal (q24h: -2.1 mmHg; q12h: -4.1 mmHg) and glaucomatous dogs (q24h: -14.2 mmHg; q12h: -17.7 mmHg; p < .0001). There was no significant difference in the treatment effect when comparing FDC to latanoprost. Both FDC and latanoprost administration resulted in similarly significant pupil constriction (p < .0001). The FDC administration was well-tolerated but resulted in conjunctival hyperemia.

CONCLUSIONS

Once or twice daily administration of netarsudil-latanoprost FDC (Rocklatan™) and latanoprost was equally effective in lowering IOP in normal and OAG-affected dogs. There was no netarsudil-related added treatment effect.

Netarsudil Improves Trabecular Outflow Facility in Patients with Primary Open Angle Glaucoma or Ocular Hypertension: A Phase 2 Study

PURPOSE

Intraocular pressure (IOP) reduction is key to controlling primary open angle glaucoma (POAG). Pharmacotherapies for POAG or ocular hypertension (OHT) commonly lower IOP by increasing uveoscleral outflow or decreasing aqueous humor production. Netarsudil (Rhopressa), a Rho kinase inhibitor, reduces IOP by improving trabecular outflow facility, which is reduced in POAG. We investigated the effects of netarsudil on aqueous humor dynamics in patients with POAG or OHT.

DESIGN

Double-masked, randomized, vehicle-controlled, Phase 2 trial.

METHODS

Netarsudil 0.02% was instilled in 1 eye and vehicle into the contralateral eye of 20 patients once daily in the morning for 7 days. The primary endpoint was change in mean diurnal outflow facility on day 8 versus that on day 1 (baseline). Outflow facility was measured by using Schiøtz tonography, IOP by pneumotonometry, and episcleral venous pressure (EVP) by automated venomanometry.

RESULTS

Eighteen patients (90%) completed the study. Mean diurnal outflow facility increased 0.039 versus 0.007 µL/min/mm Hg from baseline in the netarsudil- and the vehicle-treated groups, respectively (P < .001 vs. baseline for netarsudil), a treatment difference of 0.03 µL/min/mm Hg (P ≤ .001). Mean diurnal IOP change from baseline at day 8 was -4.52 mm Hg for netarsudil versus -0.98 mm Hg for vehicle, a treatment difference of -3.54 mm Hg (P < .0001). Mean diurnal EVP change from baseline was -0.79 mm Hg in the netarsudil-treated group versus 0.10 mm Hg for vehicle, a treatment difference of -0.89 mm Hg (P < .001). All patients reporting an adverse event reported conjunctival hyperemia of mild or moderate severity.

CONCLUSIONS

Netarsudil acts on the conventional outflow pathway, both proximal and distal, to significantly reduce IOP in POAG and OHT by improving trabecular outflow facility and decreasing EVP.

A multicenter, open-label study of netarsudil for the reduction of elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension in a real-world setting

OBJECTIVE

Assess the real-world efficacy of netarsudil, either as monotherapy or concomitant therapy, in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT) requiring modification of intraocular pressure (IOP)-lowering treatment.

METHODS

Multicenter, prospective, interventional, open-label, Phase 4 study, clinical trial registration number: NCT03808688. Netarsudil ophthalmic solution 0.02% was prescribed at the recommended once-daily dosage, with treatment regimens determined by the investigators. Netarsudil could be used alone or in combination with other IOP-lowering medications, consistent with standard clinical practice. Primary efficacy endpoint: percentage reduction from baseline IOP at week 12.

RESULTS

Among 261 enrolled patients, 242 received ≥1 netarsudil dose and had ≥1 follow-up IOP measurement (efficacy population). Mean IOP in patients who were treatment-naïve at baseline and using netarsudil as monotherapy (n = 24) decreased by 16.9%. Netarsudil monotherapy was comparable in efficacy to prior therapy across subgroups, and those who replaced prostaglandin analog (n = 57) monotherapy demonstrated reduction of 2.5% from prostaglandin analog-treated baseline values. Among patients who used netarsudil as concomitant therapy (n = 151), reductions in mean IOP (± standard deviation) to week 12 were seen across subgroups who added netarsudil to a single agent (4.3 ± 2.88 mmHg; 20.5%) or ≥2 classes of concomitant therapy (4.5 ± 4.08 mmHg; 20.9%) and who used netarsudil to replace ≥1 other drug classes (0.4 ± 2.47 mmHg; 1.7%). Of 260 netarsudil-treated patients, 41 (15.8%) discontinued, including 29 (11.2%) due to adverse events.

CONCLUSIONS

In the real-world treatment of patients with OAG or OHT, netarsudil consistently maintained IOP control when it replaced previous IOP-lowering therapies and provided additional IOP-lowering efficacy when added to other treatments.

Phase 2 Randomized Clinical Study of Netarsudil Ophthalmic Solution in Japanese Patients with Primary Open-Angle Glaucoma or Ocular Hypertension

INTRODUCTION

Netarsudil reduces intraocular pressure (IOP) by increasing aqueous outflow through the trabecular meshwork (TM) pathway and decreasing episcleral venous pressure. The primary objective of this phase 2 study was to evaluate ocular hypotensive efficacy and safety of three netarsudil concentrations (0.01%, 0.02%, and 0.04%) relative to its placebo over 4 weeks in Japanese patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT).

METHODS

Patients were randomized to one of four treatment arms, netarsudil ophthalmic solution 0.01%, 0.02%, 0.04%, or placebo, and treated once-daily (QD) in the evening (P.M.) for 4 weeks. The primary efficacy variable was mean diurnal IOP (average of diurnal time points at 9 A.M., 11 A.M., and 4 P.M.) at week 4.

RESULTS

A total of 215 patients were randomized and 207 (96.3%) completed the study. The mean of mean diurnal IOP at baseline ranged from 20.28 to 21.14 mmHg across groups. At week 4, least squares (LS) mean of mean diurnal IOP adjusted for baseline was 16.53, 15.82, 16.06, and 18.94 mmHg in the netarsudil 0.01%, 0.02%, 0.04%, and placebo groups, respectively, demonstrating the superiority of netarsudil (all concentrations) over placebo. At week 4, mean reduction (mean percentage reduction) from baseline in mean diurnal IOP was 4.10 (19.8%), 4.80 (23.5%), 4.81 (23.8%), and 1.73 mmHg (8.2%), respectively, demonstrating statistically significant reductions (p < 0.0001) in all netarsudil concentrations over placebo. Adverse events (AEs) occurred in a concentration-dependent manner, and the incidence of ocular AEs was 34.5%, 42.6%, 68.6%, and 9.1% in the netarsudil 0.01%, 0.02%, 0.04%, and placebo groups, respectively. The most frequently reported AE was conjunctival hyperemia, with an incidence of 23.6%, 37.0%, 56.9%, and 1.8%, respectively. No serious AEs were reported.

CONCLUSION

Netarsudil ophthalmic solutions 0.01%, 0.02%, and 0.04% dosed QD (P.M.) demonstrated superiority to placebo in terms of hypotensive effectiveness at week 4 and were found to be safe and generally well tolerated. Netarsudil 0.02% QD provided an optimal efficacy and safety profile for the treatment of Japanese patients with POAG or OHT.

TRIAL REGISTRATION

NCT03844945.

Physiologic Consequences of Caveolin-1 Ablation in Conventional Outflow Endothelia

Purpose

Polymorphisms at the caveolin-1/2 locus are associated with glaucoma and IOP risk and deletion of caveolin-1 (Cav1) in mice elevates IOP and reduces outflow facility. However, the specific location/cell type responsible for Cav1-dependent regulation of IOP is unclear. We hypothesized that endothelial Cav1 in the conventional outflow (CO) pathway regulate IOP via endothelial nitric oxide synthase (eNOS) signaling.

Methods

We created a mouse with targeted deletion of Cav1 in endothelial cells (Cav1ΔEC) and evaluated IOP, outflow facility, outflow pathway distal vascular morphology, eNOS phosphorylation, and tyrosine nitration of iridocorneal angle tissues by Western blotting.

Results

Endothelial deletion of Cav1 resulted in significantly elevated IOP versus wild-type mice but not a concomitant decrease in outflow facility. Endothelial Cav1 deficiency did not alter the trabecular meshwork or Schlemm's canal morphology, suggesting that the effects observed were not due to developmental deformities. Endothelial Cav1 deletion resulted in eNOS hyperactivity, modestly increased protein nitration, and significant enlargement of the drainage vessels distal to Schlemm's canal. L-Nitro-arginine methyl ester treatment reduced outflow in Cav1ΔEC but not wild-type mice and had no effect on the size of drainage vessels. Endothelin-1 treatment decrease the outflow and drainage vessel size in both wild-type and Cav1ΔEC mice.

Conclusions

Our results suggest that hyperactive eNOS signaling in the CO pathway of both Cav1ΔEC and global Cav1 knockout mice results in chronic dilation of distal CO vessels and protein nitration, but that Cav1 expression in the trabecular meshwork is sufficient to rescue CO defects reported in global Cav1 knockout mice.

Anti-fibrotic activity of a rho-kinase inhibitor restores outflow function and intraocular pressure homeostasis

Glucocorticoids are widely used as an ophthalmic medication. A common, sight-threatening adverse event of glucocorticoid usage is ocular hypertension, caused by dysfunction of the conventional outflow pathway. We report that netarsudil, a rho-kinase inhibitor, decreased glucocorticoid-induced ocular hypertension in patients whose intraocular pressures were poorly controlled by standard medications. Mechanistic studies in our established mouse model of glucocorticoid-induced ocular hypertension show that netarsudil both prevented and reduced intraocular pressure elevation. Further, netarsudil attenuated characteristic steroid-induced pathologies as assessed by quantification of outflow function and tissue stiffness, and morphological and immunohistochemical indicators of tissue fibrosis. Thus, rho-kinase inhibitors act directly on conventional outflow cells to prevent or attenuate fibrotic disease processes in glucocorticoid-induced ocular hypertension in an immune-privileged environment. Moreover, these data motivate the need for a randomized prospective clinical study to determine whether netarsudil is indeed superior to first-line anti-glaucoma drugs in lowering steroid-induced ocular hypertension.

Reticular Epithelial Edema: An Uncommon Side Effect of ROCK/NET Inhibitor Netarsudil

A 66-year-old female with advanced primary open-angle glaucoma and Descemet's stripping endothelial keratoplasty OD with previously noted inferior stromal edema presented with a 1-month history of progressive decreased visual acuity after starting netarsudil twice daily. Her best-corrected visual acuity was 20/80 OD and no light perception OS. The right cornea was notable for inferior small epithelial bullae in a reticular pattern from 2 to 9 o'clock encroaching on the visual axis involving both sides of the graft-host junction. The reticular epithelial edema resolved upon discontinuation of netarsudil and best-corrected visual acuity improved to 20/50 but was limited by persistent stromal edema. We report a patient with a history of a partially decompensated Descemet's stripping endothelial keratoplasty who develops reticular epithelial corneal edema after starting netarsudil. This unique pattern of edema may present in the setting of preexisting endothelial cell dysfunction when netarsudil is used, a complication not noted in the Food and Drug Administration (FDA) trials.

Pooled Efficacy and Safety Profile of Netarsudil Ophthalmic Solution 0.02% in Patients With Open-angle Glaucoma or Ocular Hypertension

Supplemental Digital Content is available in the text.

Precis:

In pooled phase III analyses, once-daily netarsudil 0.02% resulted in intraocular pressure (IOP) reduction that was noninferior to twice-daily timolol 0.5%, with minimal treatment-related serious or systemic adverse events (AEs). Ocular AEs were generally tolerable.

Purpose:

The purpose of this study was to assess the efficacy and safety of the Rho kinase inhibitor netarsudil in patients with open-angle glaucoma or ocular hypertension.

Patients and Methods:

Pooled analysis of data from the ROCKET-1 to 4 phase III studies of once-daily (PM) netarsudil or twice-daily timolol in patients with open-angle glaucoma or ocular hypertension. The primary efficacy measure was mean IOP at 8:00 am, 10:00 am, and 4:00 pm at week 2, week 6, and month 3 in patients with baseline IOP <25 mm Hg.

Results:

In the pooled primary efficacy population (netarsudil, n=494; timolol, n=510), once-daily netarsudil was noninferior to twice-daily timolol at all 9 timepoints through month 3. Mean treated IOP ranged from 16.4 to 18.1 mm Hg among netarsudil-treated patients and 16.8 to 17.6 mm Hg among timolol-treated patients. In the pooled safety population (n=839 in each treatment group), treatment-related serious AEs occurred at similar frequencies in each treatment group (netarsudil, 0.1%; timolol, 0%). The most common ocular AE, conjunctival hyperemia (netarsudil, 54.4%; timolol, 10.4%), was graded as mild in 77.6% (354/456) of affected netarsudil-treated patients.

Conclusions:

Once-daily netarsudil resulted in IOP lowering that was noninferior to twice-daily timolol, with tolerable ocular AEs that were generally mild and self-resolving. As a first-in-class agent in the United States, with a novel mechanism of action, netarsudil may provide a useful therapeutic option for patients who would benefit from IOP lowering.

Effects of Ripasudil on Open-Angle Glaucoma after Circumferential Suture Trabeculotomy Ab Interno

We evaluated the effects of ripasudil on the distal aqueous outflow tract in patients with open-angle glaucoma (OAG) who underwent a 360° suture trabeculotomy ab interno followed by ripasudil treatment beginning 1 month postoperatively. We compared 27 of these patients, by using propensity score analysis, with 27 patients in a matched control group who had no ripasudil treatment. We assessed the changes in the mean intraocular pressure (IOP) and the relationship between the IOP changes and background factors. All eyes had a complete 360° Schlemm’s canal incision and phacoemulsification. The mean IOP at 1 and 3 months after ripasudil administration were significantly reduced by −1.7 ± 1.9 mmHg (p < 0.0001) and −1.3 ± 2.3 mmHg (p = 0.0081) in the ripasudil group, respectively, but IOP in the control group was not significantly reduced. The IOP reduction was significantly associated with the IOP before ripasudil treatment (p < 0.001). In conclusion, the use of ripasudil for patients with OAG after circumferential incision of the Schlemm’s canal produced significant IOP reductions. Ripasudil may affect the distal outflow tract, thereby leading to the IOP reduction.

Effect of postoperative corticosteroids on surgical outcome and aqueous autotaxin following combined cataract and microhook ab interno trabeculotomy

To evaluate the effect of postoperative corticosteroids on surgical outcome and autotaxin (ATX) levels after microhook ab interno trabeculotomy combined with cataract surgery (μLOT-CS), prospective, consecutive non-randomized case series comparing outcomes of 30 eyes with primary open angle glaucoma was performed. The aqueous ATX, intraocular pressure (IOP) and glaucoma medications were monitored for 3 months postoperatively. An in-vivo mouse μLOT model was generated. In vitro, ATX and fibrotic changes induced by dexamethasone (Dex) treatment following scratch (S) in cultured human trabecular meshwork (hTM) cells were assessed by immunofluorescence, immunoenzymatic assay, and RT-qPCR. Postoperative ATX at 1 week and the number of antiglaucoma medications at 3 months were significantly lower in non-steroid group, and steroid use was the only variable significantly associated with postoperative medications at 3 months in multiregression analyses. In vitro, ATX activity was significantly upregulated in the Dex + S group, and αSMA was significantly upregulated in the Dex and Dex + S groups. Fibronectin and COL1A1 were significantly upregulated in the S group. μLOT-CS decreased IOP and medications in the overall cohort, and non-use of postoperative steroids resulted in a smaller number of postoperative medications. Limiting postoperative steroids in μLOT may minimize IOP elevation and postoperative fibrosis.

[Rho kinase inhibitors as new local therapy option in primary open angle glaucoma]

BACKGROUND

In 2014 in Japan and 2017 in the USA, the Rho-kinase inhibitors were approved as a new antiglaucomatous substance group and will now be launched in Europe.

OBJECTIVE

On this occasion the current state of knowledge on Rho-kinase inhibitors is presented.

METHODS

In intensive search in PubMed the relevant experimental and clinical literature on the Rho-kinase inhibitors ripasudil and netarsudil and the combination of netarsudil and latanoprost were selected and compiled for this review.

RESULTS

The intraocular pressure lowering efficacy of ripasudil and netarsudil is in the range of the beta blocker timolol and the prostaglandin analogue latanoprost. In the fixed combination netarsudil/latanoprost the intraocular pressure reduction is greater than that of the single components and reaches a target pressure of below 15 mm Hg in 32%. Conjunctival hyperemia with 53-65% is the most common local side effect. Systemic side effects are very rare and so far there are no contraindications.

CONCLUSION

The Rho-kinase inhibitors are an interesting new introduction for glaucoma therapy, as each new pressure-lowering therapy represents an additional chance to reach the individually defined target pressure level in a glaucoma patient with local therapy; however, many of the pleiotropic effects associated with Rho-kinase inhibitors have so far only been found experimentally and will require clinical confirmation in the future.

In vivo estimation of murine iris stiffness using finite element modeling

The iris plays an important role in certain types of glaucoma, including primary angle-closure glaucoma and pigmentary glaucoma. Iris mechanics are also important in influencing trabecular meshwork deformation in response to intraocular pressure changes in some animal species. Although mice are widely used to study ocular disease, including glaucoma, the in vivo biomechanical properties of the murine iris are unknown. Thus, the primary objective of this study was to estimate murine iris biomechanical stiffness. We used optical coherence tomography (OCT) images of the anterior segment of living mice (n = 13, age = 7.3 ± 3.2 [mean ± SD] months) at sequentially increasing IOP levels, observing IOP-dependent iris deformations. We then used an inverse finite element model to predict iris deformations under the same conditions, estimating iris stiffness by maximizing agreement between OCT data and numerical simulations. Our results show an in vivo murine iris stiffness of 96.1 ± 54.7 kPa (mean ± SD), which did not correlate with age but was dependent on gender. Our results further showed strong evidence of reverse pupillary block, with mean posterior chamber pressure remaining at approximately 12 mmHg even as anterior chamber pressure was set to much higher levels. Our approach to monitoring iris stiffness in vivo is applicable to study potential changes of iris stiffness in various pathophysiological conditions and thus has significant potential for clinical care of ocular disease involving iris biomechanics.

A Small Molecule Inhibitor of VE-PTP Activates Tie2 in Schlemm's Canal Increasing Outflow Facility and Reducing Intraocular Pressure

Purpose

Tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie2) activation in Schlemm's canal (SC) endothelium is required for the maintenance of IOP, making the angiopoietin/Tie2 pathway a target for new and potentially disease modifying glaucoma therapies. The goal of the present study was to examine the effects of a Tie2 activator, AKB-9778, on IOP and outflow function.

Methods

AKB-9778 effects on IOP was evaluated in humans, rabbits, and mice. Localization studies of vascular endothelial protein tyrosine phosphatase (VE-PTP), the target of AKB-9778 and a negative regulator of Tie2, were performed in human and mouse eyes. Mechanistic studies were carried out in mice, monitoring AKB-9778 effects on outflow facility, Tie2 phosphorylation, and filtration area of SC.

Results

AKB-9778 lowered IOP in patients treated subcutaneously for diabetic eye disease. In addition to efficacious, dose-dependent IOP lowering in rabbit eyes, topical ocular AKB-9778 increased Tie2 activation in SC endothelium, reduced IOP, and increased outflow facility in mouse eyes. VE-PTP was localized to SC endothelial cells in human and mouse eyes. Mechanistically, AKB-9778 increased the filtration area of SC for aqueous humor efflux in both wild type and in Tie2+/- mice.

Conclusions

This is the first report of IOP lowering in humans with a Tie2 activator and functional demonstration of its action in remodeling SC to increase outflow facility and lower IOP in fully developed mice. Based on these studies, a phase II clinical trial is in progress to advance topical ocular AKB-9778 as a first in class, Tie2 activator for treatment for ocular hypertension and glaucoma.

The vital role for nitric oxide in intraocular pressure homeostasis

Catalyzed by endothelial nitric oxide (NO) synthase (eNOS) activity, NO is a gaseous signaling molecule maintaining endothelial and cardiovascular homeostasis. Principally, NO regulates the contractility of vascular smooth muscle cells and permeability of endothelial cells in response to either biochemical or biomechanical cues. In the conventional outflow pathway of the eye, the smooth muscle-like trabecular meshwork (TM) cells and Schlemm's canal (SC) endothelium control aqueous humor outflow resistance, and therefore intraocular pressure (IOP). The mechanisms by which outflow resistance is regulated are complicated, but NO appears to be a key player as enhancement or inhibition of NO signaling dramatically affects outflow function; and polymorphisms in NOS3, the gene that encodes eNOS modifies the relation between various environmental exposures and glaucoma. Based upon a comprehensive review of past foundational studies, we present a model whereby NO controls a feedback signaling loop in the conventional outflow pathway that is sensitive to changes in IOP and its oscillations. Thus, upon IOP elevation, the outflow pathway tissues distend, and the SC lumen narrows resulting in increased SC endothelial shear stress and stretch. In response, SC cells upregulate the production of NO, relaxing neighboring TM cells and increasing permeability of SC's inner wall. These IOP-dependent changes in the outflow pathway tissues reduce the resistance to aqueous humor drainage and lower IOP, which, in turn, diminishes the biomechanical signaling on SC. Similar to cardiovascular pathogenesis, dysregulation of the eNOS/NO system leads to dysfunctional outflow regulation and ocular hypertension, eventually resulting in primary open-angle glaucoma.

A Randomized, Phase 2 Study of 24-h Efficacy and Tolerability of Netarsudil in Ocular Hypertension and Open-Angle Glaucoma

Introduction

Pharmacotherapy to lower intraocular pressure (IOP) is a mainstay of treatment aimed at delaying progression of visual field loss in ocular hypertension (OHT) and open-angle glaucoma (OAG), but some topical treatments are less effective in controlling IOP at night. Peak IOP may be related to glaucoma progression and can occur outside office hours. A phase 2 study was conducted to evaluate the IOP-lowering efficacy of netarsudil across the diurnal and nocturnal periods.

Methods

This was a randomized, double-masked, single-center, vehicle-controlled, 9-day study. After washout of any prior ocular hypotensive agents, 12 patients with OHT or OAG underwent baseline IOP assessment at 15:00, 18:00, 21:00, 00:00, 03:00, 06:00, 09:00, and 12:00 h on day 1/day 2. Participants were then randomized in a 2:1 ratio to netarsudil ophthalmic solution 0.02% (n = 8) or vehicle (n = 4) for 7 days of self-administered dosing each evening. IOP was assessed at the same time points on day 8/day 9. All measurements were conducted with a Perkins tonometer in habitual positions by day (seated) and at night (supine).

Results

Baseline mean 24-h IOP was 22.4 mmHg in the netarsudil group and 22.9 mmHg in the vehicle group. Netarsudil was associated with a reduction in mean nocturnal IOP (measurements at 21:00, 00:00, 03:00, 06:00 h) of 3.5 mmHg, which was significant relative to baseline nocturnal IOP (P < 0.001) and the reduction in the vehicle group (0.4 mmHg; P < 0.001 vs. netarsudil). Reduction in mean diurnal IOP with netarsudil (3.5 mmHg) was the same as the nocturnal reduction and statistically significant versus baseline (P < 0.001) and the vehicle group (0.9 mmHg; P < 0.01). The magnitude of IOP reductions with netarsudil was consistent at each time point assessed over the 24-h period. No adverse events were reported.

Conclusion

Netarsudil exhibited consistent IOP-lowering efficacy over a 24-h period in this short-term study.

Trial Registration

Clinicaltrials.gov identifier: NCT02874846.

When pressure inside the eye (called intraocular pressure [IOP]) builds up, a patient may develop a condition known as glaucoma, in which damage to the optic nerve and possibly irreversible vision loss occur. Glaucoma can be preceded in some patients by a condition called ocular hypertension (OHT). Patients with OHT and the most common type of glaucoma (open-angle glaucoma [OAG]) should be treated to lower their IOP and decrease the risk for progressive visual loss. Several studies that have evaluated 24-h IOP control have indicated that some eye drops lower IOP less effectively at night than during the day. A pilot study was conducted in 12 patients with OHT or OAG to evaluate netarsudil’s IOP lowering effect during the day and at night. After a week of treatment with netarsudil or a similar eye drop that did not contain the active drug, patients who took netarsudil experienced the same decrease in IOP at night as during the day. IOP was statistically lower with netarsudil than with the drug-free comparator both during the day and at night. Although this was a small study in 12 patients, the results are of interest because they suggest that netarsudil might consistently reduce IOP over a 24-h period.

Effects of Netarsudil on Actin-Driven Cellular Functions in Normal and Glaucomatous Trabecular Meshwork Cells: A Live Imaging Study

The actin cytoskeleton of trabecular meshwork (TM) cells is a therapeutic target for lowering intraocular pressure (IOP) in glaucoma patients. Netarsudil (the active ingredient in Rhopressa^TM) is a Rho-associated protein kinase inhibitor that induces disassembly of actin stress fibers. Here, we used live cell imaging of SiR-actin-labeled normal (NTM) and glaucomatous TM (GTM) cells to investigate actin dynamics during actin-driven biological processes with and without netarsudil treatment. Actin stress fibers were thicker in GTM than NTM cells and took longer (>120 min) to disassemble following addition of 1 µM netarsudil. Actin-rich extracellular vesicles (EVs) were derived by two mechanisms: exocytosis of intracellular-derived vesicles, and cleavage of filopodial tips, which detached the filopodia from the substratum, allowing them to retract to the cell body. While some phagocytosis was noted in untreated TM cells, netarsudil potently stimulated phagocytic uptake of EVs. Netarsudil treatment induced lateral fusion of tunneling nanotubes (TNTs) that connected adjacent TM cells; TNTs are important for TM cellular communication. Together, our results suggest that netarsudil may clear outflow channels in TM tissue by inducing phagocytosis and/or by modulating TM communication via EVs and TNTs. These cellular functions likely work together to regulate IOP in normal and glaucomatous TM.

The β4-Subunit of the Large-Conductance Potassium Ion Channel KCa1.1 Regulates Outflow Facility in Mice

Purpose

The large-conductance calcium-activated potassium channel K_Ca1.1 (BK_Ca, maxi-K) influences aqueous humor outflow facility, but the contribution of auxiliary β-subunits to K_Ca1.1 activity in the outflow pathway is unknown.

Methods

Using quantitative polymerase chain reaction, we measured expression of β-subunit genes in anterior segments of C57BL/6J mice (Kcnmb1-4) and in cultured human trabecular meshwork (TM) and Schlemm's canal (SC) cells (KCNMB1-4). We also measured expression of Kcnma1/KCNMA1 that encodes the pore-forming α-subunit. Using confocal immunofluorescence, we visualized the distribution of β₄ in the conventional outflow pathway of mice. Using iPerfusion, we measured outflow facility in enucleated mouse eyes in response to 100 or 500 nM iberiotoxin (IbTX; N = 9) or 100 nM martentoxin (MarTX; N = 12). MarTX selectively blocks β₄-containing K_Ca1.1 channels, whereas IbTX blocks K_Ca1.1 channels that lack β₄.

Results

Kcnmb4 was the most highly expressed β-subunit in mouse conventional outflow tissues, expressed at a level comparable to Kcnma1. β₄ was present within the juxtacanalicular TM, appearing to label cellular processes connecting to SC cells. Accordingly, KCNMB4 was the most highly expressed β-subunit in human TM cells, and the sole β-subunit in human SC cells. To dissect functional contribution, MarTX decreased outflow facility by 35% (27%, 42%; mean, 95% confidence interval) relative to vehicle-treated contralateral eyes, whereas IbTX reduced outflow facility by 16% (6%, 25%).

Conclusions

The β₄-subunit regulates K_Ca1.1 activity in the conventional outflow pathway, significantly influencing outflow function. Targeting β₄-containing K_Ca1.1 channels may be a promising approach to lower intraocular pressure to treat glaucoma.

Integral role for lysyl oxidase-like-1 in conventional outflow tissue function and behavior

Lysyl oxidase-like-1 (LOXL1), a vital crosslinking enzyme in elastin fiber maintenance, is essential for the stability and strength of elastic vessels and tissues. Variants in the LOXL1 locus associate with a dramatic increase in risk of exfoliation syndrome (XFS), a systemic fibrillopathy, which often presents with ocular hypertension and exfoliation glaucoma (XFG). We examined the role of LOXL1 in conventional outflow function, the prime regulator of intraocular pressure (IOP). Using Loxl1^-/- , Loxl1^+/- , and Loxl1^+/+ mice, we observed an inverse relationship between LOXL1 expression and IOP, which worsened with age. Elevated IOP in Loxl1^-/- mice was associated with a larger globe, decreased ocular compliance, increased outflow facility, extracellular matrix (ECM) abnormalities, and dilated intrascleral veins, yet, no dilation of arteries or capillaries. Interestingly, in living Loxl1^-/- mouse eyes, Schlemm's canal (SC) was less susceptible to collapse when challenged with acute elevations in IOP, suggesting elevated episcleral venous pressure (EVP). Thus, LOXL1 expression is required for normal IOP control, while ablation results in altered ECM repair/homeostasis and conventional outflow physiology. Dilation of SC and distal veins, but not arteries, is consistent with key structural and functional roles for elastin in low-pressure vessels subjected to cyclical mechanical stress.

Ocular Disease Therapeutics: Design and Delivery of Drugs for Diseases of the Eye

The ocular drug discovery field has evidenced significant advancement in the past decade. The FDA approvals of Rhopressa, Vyzulta, and Roclatan for glaucoma, Brolucizumab for wet age-related macular degeneration (wet AMD), Luxturna for retinitis pigmentosa, Dextenza (0.4 mg dexamethasone intracanalicular insert) for ocular inflammation, ReSure sealant to seal corneal incisions, and Lifitegrast for dry eye represent some of the major developments in the field of ocular therapeutics. A literature survey also indicates that gene therapy, stem cell therapy, and target discovery through genomic research represent significant promise as potential strategies to achieve tissue repair or regeneration and to attain therapeutic benefits in ocular diseases. Overall, the emergence of new technologies coupled with first-in-class entries in ophthalmology are highly anticipated to restructure and boost the future trends in the field of ophthalmic drug discovery. This perspective focuses on various aspects of ocular drug discovery and the recent advances therein. Recent medicinal chemistry campaigns along with a brief overview of the structure-activity relationships of the diverse chemical classes and developments in ocular drug delivery (ODD) are presented.

Plant-derived angiogenin fusion protein's cytoprotective effect on trabecular meshwork damage induced by Benzalkonium chloride in mice

Background

Benzalkonium chloride (BAK), commonly used in glaucoma treatment, is an eye drop preservative with dose-dependent toxicity. Previous studies have observed the multi-functional benefits of angiogenin (ANG) against glaucoma. In our study, we evaluated ANG’s cytoprotective effect on the trabecular meshwork (TM) damage induced by BAK. Additionally, we developed a plant-derived ANG fusion protein and evaluated its effect on TM structure and function.

Methods

We synthesized plant-derived ANG (ANG-FcK) by fuzing immunoglobulin G’s Fc region and KDEL to conventional recombinant human ANG (Rh-ANG) purified from transgenic tobacco plants. We established a mouse model using BAK to look for degenerative changes in the TM, and to evaluate the protective effects of ANG-FcK and Rh-ANG. Intraocular pressure (IOP) was measured for 4 weeks and ultrastructural changes, deposition of fluorescent microbeads, type I and IV collagen, fibronectin, laminin and α-SMA expression were analyzed after the mice were euthanized.

Results

TM structural and functional degeneration were induced by 0.1% BAK instillation in mice. ANG co-treatment preserved TM outflow function, which we measured using IOP and a microbead tracer. ANG prevented phenotypic and ultrastructure changes, and that protective effect might be related to the anti-fibrosis mechanism. We observed a similar cytoprotective effect in the BAK-induced degenerative TM mouse model, suggesting that plant-derived ANG-FcK could be a promising glaucoma treatment.

Ripasudil Hydrochloride Hydrate in the Treatment of Glaucoma: Safety, Efficacy, and Patient Selection

Reduction of intraocular pressure (IOP) is the only reliable treatment for glaucoma that maintains the patient’s visual function throughout life, and IOP-lowering eyedrops are the mainstay of therapy. Ripasudil hydrochloride hydrate (brand name: Glanatec ophthalmic solution 0.4%; Kowa Company, Ltd., Japan) is a Rho-associated coiled-coil-containing protein kinase (ROCK) inhibitor that lowers IOP by increasing conventional aqueous outflow. Since the approval of ripasudil eyedrops in 2014, a large store of clinical data has been amassed in Japan. With regard to safety, conjunctival hyperemia is the most common adverse drug reaction (ADR) and is usually transient and mild. Blepharitis and allergic conjunctivitis are other major local ADRs. Systemic ADRs are rare, but we should be wary of allergic reactions. With regard to efficacy, ripasudil is expected to lower IOP in almost all glaucoma subtypes (including primary open-angle glaucoma, secondary glaucoma, and primary angle-closure glaucoma) and in all patterns of treatment initiation (monotherapy, combination therapy, switching therapy, and add-on therapy). However, the status of the trabecular meshwork may affect the IOP-lowering effect of ripasudil. In patient selection, current evidence-based information on the safety and efficacy of ripasudil should be fully considered. As irreversible damage to the trabecular meshwork would considerably affect efficacy, it may be better to start ripasudil treatment during an early stage of glaucoma.

Dose-dependent effects of netarsudil, a Rho-kinase inhibitor, on the distal outflow tract

PURPOSE

To characterize the effects of netarsudil on the aqueous humor outflow tract distal to the trabecular meshwork (TM). We hypothesized that netarsudil increases outflow facility in eyes with and without circumferential ab interno trabeculectomy (AIT) that removes the TM.

METHODS

Sixty-four porcine anterior segment cultures were randomly assigned to groups with (n = 32) and without circumferential AIT (n = 32). Cultures were exposed to 0.1, 1, and 10 μM netarsudil (N = 8 eyes per concentration). For each concentration, IOP and vessel diameters were compared with their respective pretreatment baselines. Outflow tract vessel diameters were assessed by spectral-domain optical coherence tomography (SDOCT) and rendered in 4D (XYZ time series).

RESULTS

Netarsudil at 1 μM reduced IOP both in eyes with TM (- 0.60 ± 0.24 mmHg, p = 0.01) and in eyes without TM (- 1.79 ± 0.42 mmHg, p < 0.01). At this concentration, vessels of the distal outflow tract dilated by 72%. However, at 0.1 μM netarsudil elevated IOP in eyes with TM (1.59 ± 0.36 mmHg, p < 0.001) as well as in eyes without TM (0.23 ± 0.32 mmHg, p < 0.001). Vessels of the distal outflow tract constricted by 31%. Similarly, netarsudil at a concentration of 10 μM elevated IOP both in eyes with TM (1.91 ± 0.193, p < 0.001) and in eyes without TM (3.65 ± 0.86 mmHg, p < 0.001). At this concentration, outflow tract vessels constricted by 27%.

CONCLUSION

In the porcine anterior segment culture, the dose-dependent IOP changes caused by netarsudil matched the diameter changes of distal outflow tract vessels. Hyper- and hypotensive properties of netarsudil persisted after TM removal.

In Vivo Imaging of Schlemm's Canal and Limbal Vascular Network in Mouse Using Visible-Light OCT

Purpose

To validate the ability of visible-light optical coherence tomography (vis-OCT) in imaging the full Schlemm's canal (SC) and its surrounding limbal vascular network in mice in vivo through a compound circumlimbal scan.

Methods

We developed an anterior segment vis-OCT system and a compound circumlimbal scanning method, which montages eight rotated raster scans. We calibrated the circumlimbal scan geometry using a three-dimensional printed phantom eyeball before imaging wild-type C57BL/6J mice. We measured SC size by segmenting SC cross sections from vis-OCT B-scan images and imaged the limbal microvascular network using vis-OCT angiography (vis-OCTA). To introduce changes in SC size, we used a manometer to adjust the intraocular pressure (IOP) to different levels. To create additional optical scattering contrast to enhance SC imaging, we surgically increased the episcleral venous pressure (EVP) and caused blood reflux into SC.

Results

Using the compound circumlimbal scan, our anterior segment vis-OCT noninvasively imaged the full SC and limbal microvascular network in mouse for the first time. We observed an average 123% increase in SC volume when we decreased the IOP by 10 mm Hg from the baseline IOP of 7 to 10 mm Hg and an average 72% decrease in SC volume when the IOP level was elevated by 10 mm Hg from the baseline IOP. We also observed location-dependent SC size responses to IOP changes. Blood reflux caused by increased EVP enabled vis-OCTA to directly visualize SC, which matched well with the segmented SC.

Conclusions

Vis-OCT and vis-OCTA can accurately image the entire SC and limbal microvascular network in vivo using the compound circumlimbal scan. Vis-OCT is also able to quantitatively measure SC responses to changing IOP levels.

Fixed-Dose Combination of Netarsudil and Latanoprost in Ocular Hypertension and Open-Angle Glaucoma: Pooled Efficacy/Safety Analysis of Phase 3 MERCURY-1 and -2

INTRODUCTION

New open-angle glaucoma (OAG) and ocular hypertension (OHT) therapies that reduce treatment burden and improve outcomes relative to currently available agents are needed. Netarsudil, a novel Rho kinase inhibitor approved by the US Food and Drug Administration, reduces intraocular pressure (IOP) by increasing trabecular outflow. Two phase 3 superiority studies compared a fixed-dose combination (FDC) of netarsudil and the prostaglandin latanoprost with each active component for IOP-lowering efficacy.

METHODS

Pooled efficacy and safety data were analyzed from MERCURY-1 and -2 studies in patients with OAG or OHT. Patients instilled one drop of netarsudil (0.02%)/latanoprost (0.005%) FDC (n = 483), netarsudil (0.02%, n = 499), or latanoprost (0.005%, n = 486) into each eye once-daily between 20:00 and 22:00. IOP was measured at 08:00, 10:00, and 16:00 at weeks 2, 6, and the primary endpoint at month 3.

RESULTS

Baseline mean diurnal IOP was 23.6, 23.6, and 23.5 mmHg in netarsudil/latanoprost FDC, netarsudil, and latanoprost groups, respectively. Mean diurnal IOP in each group was 15.3, 18.1, and 17.5 mmHg at week 2, 15.7, 18.4, and 17.4 mmHg at week 6, and 15.8, 18.4, and 17.3 mmHg at week 12. The netarsudil/latanoprost FDC met criteria for superiority compared with each active component (p < 0.0001 for all nine time points). At month 3, among patients randomized to netarsudil/latanoprost FDC or latanoprost, 58.4% vs 37.3% (p < 0.0001) achieved IOP ≤ 16 mmHg. Among patients randomized to netarsudil/latanoprost FDC or netarsudil or latanoprost, 30.9% vs 5.9% (p < 0.0001) vs 8.5% (p < 0.0001) achieved at least a 40% reduction from baseline in mean diurnal IOP. Pooled safety results were consistent with individual MERCURY studies.

CONCLUSION

Once-daily netarsudil/latanoprost FDC produced statistically significant and clinically relevant reductions in mean IOP that were statistically superior to IOP reductions achieved by netarsudil and latanoprost monotherapy. Results of the pooled efficacy and safety analyses were consistent with the individual studies.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers, NCT02558400 and NCT02674854.

Rho-Associated Protein Kinase Inhibitor Treatment Promotes Proliferation and Phagocytosis in Trabecular Meshwork Cells

Purpose

Continuous reductions in trabecular meshwork (TM) cellularity inhibit aqueous humor (AH) outflow, which is the main cause of primary open-angle glaucoma. Rho-associated protein kinase inhibitor (ROCKi) targets the TM to reduce intraocular pressure (IOP) and increase AH outflow facility. However, the underlying mechanisms are not entirely clear. Here, we aimed to investigate the effect of a ROCKi (Y-27632) on TM cell proliferation and phagocytosis.

Methods

Immortalized human TM (iHTM) cells, glaucomatous TM (GTM₃) cells, and primary human TM (pTM) cells were cultured and identified. The effects of various concentrations of Y-27632 on F-actin cytoskeleton were assessed using immunofluorescence. Cell proliferation effects were evaluated using a cell counting kit-8 (CCK8), cell counting, and Ki67 immunostaining. Cell phagocytosis was evaluated using immunofluorescence and flow cytometry in immortalized TM cells. C57BL/6J and Tg-MYOC^Y437H mice were used to investigate the proliferative effects of Y-27632 on TM cells in vivo. The effect of Y-27632 on IOP was monitored for 2 weeks, and the outflow facility was detected 2 weeks after IOP measurement. TM cells in mice were counted using immunohistochemistry.

Results

Y-27632 (100 μM) significantly promoted the proliferation of both immortal TM cells and pTM cells. In GTM₃ cells, phagocytosis was significantly greater in the Y-27632 group than in the control group, nearly reaching the level of phagocytosis in iHTM, as determined using immunofluorescence and flow cytometry. In Tg-MYOC^Y437H mice, treatment with Y-27632 significantly decreased IOP and increased outflow facility, which greatly influenced the long-term IOP-lowering effect. The number of TM cells in Tg-MYOC^Y437H mice was significantly improved after Y-27632 administration.

Conclusion

Y-27632 promoted cell proliferation and phagocytosis of TM cells, and its proliferative effect was demonstrated in a transgenic mouse model. These results revealed a new IOP-lowering mechanism of Y-27632 through effects on TM cells, suggesting the potential for a correlation between TM cellularity and long-term recovery of IOP.

Effects of 0.02% netarsudil ophthalmic solution on intraocular pressure of normotensive dogs

OBJECTIVES

To evaluate the effect of QD or BID 0.02% netarsudil ophthalmic solution (Aerie Pharmaceuticals) on intraocular pressure (IOP) in normotensive dogs and to describe any adverse effects.

ANIMALS STUDIED

Normotensive Labrador retriever dogs were included in this study: 10 received netarsudil in one eye and artificial tears in the contralateral eye QD, and 10 received netarsudil in one eye and artificial tears in the contralateral eye BID.

PROCEDURES

Intraocular pressure curves were acquired over a 3-day acclimation period, 5-day dosing period (QD or BID-10 dogs/group), and 3-day recovery period. Toxicity was assessed daily using slit-lamp biomicroscopy and the semiquantitative preclinical ocular toxicology scoring system.

RESULTS

Once-daily dosing did not lower IOP over the entire 5-day dosing period (95% CI 0.1 to -0.9 mm Hg, P = .20) or on the last day of dosing (95% CI 0.4 to -0.9 mm Hg, P = .65). Twice-daily dosing resulted in a statistically significant, but clinically unimportant, IOP reduction over the entire 5-day dosing period (-0.6 mm Hg; 95% CI 0.05 to -1.1 mm Hg, P = .02) and on the last day of dosing (-0.9 mm Hg; 95% CI 0.2 to -1.5 mm Hg, P = .003). Adverse events were limited to transient mild-to-moderate conjunctival hyperemia during the dosing phase in eyes receiving netarsudil vs control (P < .0001).

CONCLUSIONS

Netarsudil 0.02% ophthalmic solution twice daily resulted in a small, statistically significant, but clinically unimportant, IOP reduction in normotensive dogs. Future studies should investigate efficacy in glaucomatous dogs.