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Purpose: We studied the IOP-lowering effects of NCX 1741, a novel nitric oxide (NO)-donating derivative of the phosphodiesterase type-5 inhibitor, avanafil, in Cynomolgus monkey with laser-induced ...

Introduction: Aqueous humor and its dynamics (AHD) serve numerous functions to sustain ocular health and clear vision. Current methods to assess AHD have led to improved understanding of ocular phy...

Purpose. This study investigated how a conscious change in ocular accommodation affects intraocular pressure (IOP) and ocular biometrics in healthy adult volunteers of different ages. Methods. Thirty-five healthy volunteers without ocular disease or past ocular surgery, and with refractive error between −3.50 and +2.50 diopters, were stratified into 20, 40, and 60 year old (y.o.) age groups. Baseline measurements of central cornea thickness, anterior chamber depth, anterior chamber angle, cornea diameter, pupil size, and ciliary muscle thickness were made by autorefraction and optical coherence tomography (OCT), while IOP was measured by pneumotonometry. Each subject’s right eye focused on a target 40 cm away. Three different tests were performed in random order: (1) 10 minutes of nonaccommodation (gazing at the target through lenses that allowed clear vision without accommodating), (2) 10 minutes of accommodation (addition of a minus 3 diopter lens), and (3) 10 minutes of alternating between accommodation and nonaccommodation (1-minute intervals). IOP was measured immediately after each test. A 20-minute rest period was provided between tests. Data from 31 subjects were included in the study. ANOVA and paired t-tests were used for statistical analyses. Results. Following alternating accommodation, IOP decreased by 0.7 mmHg in the right eye when all age groups were combined ( p = 0.029). Accommodation or nonaccommodation alone did not decrease IOP. Compared to the 20 y.o. group, the 60 y.o. group had a thicker ciliary muscle within 75 μm of the scleral spur, a thinner ciliary muscle at 125–300 μm from the scleral spur, narrower anterior chamber angles, shallower anterior chambers, and smaller pupils during accommodation and nonaccommodation ( p ’s

To improve understanding of intraocular pressure (IOP) and its variance, this project identifies systemic and ocular characteristics of healthy eyes of adult volunteers including IOP variation, ocular biometrics, and aqueous humor dynamics (AHDs). These data serve as baseline controls for further studies from the Eye Dynamics and Engineering Network (EDEN) Consortium.Multicenter open-label clinical trial in healthy adults randomized to 1 week treatment with 2 approved glaucoma drugs in a crossover design.Among 135 healthy participants, 122 participants (aged 55.2 ± 8.8 years; 92 females, 30 males) completed the protocol.Participants from the University of Michigan, Mayo Clinic, and University of Nebraska Medical Center underwent measurements of ocular biometrics, AHD, and IOP using 4 tonometers. Intraocular pressure data during 3 study visits without glaucoma medications were used in the analysis. The PhenX Toolkit survey acquired standardized data on medical history, surgical history, medications, smoking and alcohol exposures, and physical measures.The variability of IOP measurements within eyes was assessed as visit-to-visit IOP variation, within-visit IOP variation, and within-visit positional IOP variation. The concordance (or correlation) between eyes was also assessed.Average positional change of4.7 mmHg was detected with a range of 0.5-11.0 mmHg. Pearson correlation of IOP between eyes within a visit was 0.87 (95% confidence interval [CI], 0.82-0.91) for Goldmann applanation tonometry, 0.91 (95% CI, 0.88-0.94) for Icare rebound tonometry, and 0.91 (95% CI, 0.88-0.94) for pneumatonometry. There was a 4% to 12% asymmetric fluctuation of 3 mmHg or more between eyes between visits using rebound tonometry, 9% with Goldmann applanation tonometry, and 3% to 4% by pneumotonometry. The coefficient of variation between visits for the same eye ranged from 11.2% to 12.9% for pneumatonometry, from 13.6% to 17.4% for rebound tonometry, and 15.8% to 16.2% for Goldmann applanation tonometry.The current study from the EDEN Consortium describes measurement methods and data analyses with emphasis on IOP variability. Future papers will focus on changes in ocular biometrics and AHD with timolol or latanoprost treatment.

Though roughly 30–50% of aqueous outflow resistance resides distal to Schlemm’s canal (SC), the morphology of the conventional outflow pathway distal to SC has not been thoroughly evaluated. This study examined the morphological changes along proximal and distal aspects of the conventional aqueous outflow pathway and their association with decreased outflow facility in an experimental model of glaucoma in cynomolgus macaques. Nd:YAG laser burns were made to 270–340 degrees of the trabecular meshwork (TM) of one eye (n = 6) or both eyes (n = 2) of each monkey to induce ocular hypertension. Distinct regions of the TM were left unlasered. Contralateral eyes (n = 5) were not lasered and were utilized as controls. Monkeys were sacrificed ≥ 60 months after their last laser treatment. All eyes were enucleated and perfused at 15 mmHg for 30 minutes to measure outflow facility. Two pairs of eyes were also perfused with fluorescein to examine segmental outflow. All eyes underwent perfusion-fixation for 1 hr. Anterior segments were cut into radial wedges and processed for light and electron microscopy. Width, height, and cross-sectional area (CSA) of SC were compared between high- and low-flow regions of control eyes, and between non-lasered regions of laser-treated eyes and control eyes. Number and CSA of intrascleral veins (ISVs) were compared between non-lasered and lasered regions of laser-treated eyes and control eyes, and between high- and low-flow regions of control eyes. Scleral collagen fibril diameter was compared between control eyes and lasered and non-lasered regions of laser-treated eyes. Median outflow facility was significantly decreased in laser-treated eyes compared to control eyes (P = 0.02). Median CSA and height of SC were smaller in high- flow regions than low-flow regions of control eyes (P < 0.05). Median width of SC was not significantly different between high- and low-flow regions of control eyes (P > 0.05). Median CSA, width, and height of SC were not different between non-lasered regions and control eyes (P > 0.05). SC was partially or completely obliterated in lasered regions. Median number of ISVs was significantly decreased in lasered regions compared to non-lasered regions (P < 0.01) and control eyes (P < 0.01). Median CSA of ISVs did not differ between these groups (P > 0.05). Median number and CSA of ISVs were not significantly different between high- and low-flow regions of control eyes (P > 0.05). Lasered regions displayed looser scleral stroma and smaller median diameter of collagen fibrils adjacent to the TM compared to non-lasered regions (P < 0.05) and control eyes (P < 0.05). Dense TM, partial to complete obliteration of SC, and a decreased number of patent ISVs may account in part for the decreased outflow facility in monkey eyes with laser-induced ocular hypertension. The significance of changes in scleral structure in laser-treated eyes warrants further investigation.

For >2 decades, EP2 agonists have been the subject of antiglaucoma research and development by scientists in industry and academia around the world. The road has led to the recent approval...

Hyposecretion of aqueous humor has been postulated to adversely affect the health of the trabecular meshwork and outflow resistance. However, the effect of medications that reduce aqueous humor production on outflow facility in living human eyes is unclear. This study evaluated the effect of timolol, an aqueous humor flow suppressant, on outflow facility in healthy eyes.Prospective, before-and-after study.In a multicenter study, 113 healthy participants over 40 years of age were included. Intraocular pressure (IOP) was measured with the participant in the sitting position by using a pneumatonometer. The outflow facility was measured with the participant in the supine position by 2-minute pneumatonography. After participants self-administered drops of timolol 0.5% for 1 week, twice daily in each eye, both measurements were repeated.Mean IOP decreased from 15.1 ± 3.0 mm Hg at baseline to 12.4 ± 2.4 mm Hg (P0.001) after 1 week of timolol use. Mean outflow facility decreased from 0.23 ± 0.08 μL/min/mm Hg at baseline to 0.18 ± 0.08 μL/min/mm Hg (P0.001) after timolol. The change in outflow facility was negatively correlated with baseline outflow facility (r = -0.51; P 0.001).Timolol reduces outflow facility in healthy human eyes, and this effect is greater in eyes with higher baseline outflow facility. This phenomenon may be related to reduced aqueous humor flow, but the precise mechanism remains to be determined.

Purpose: Two features define the future of glaucoma therapeutics: (1) greatly improved ocular hypotensive efficacy and (2) a delivery method that improves patient convenience and complianc...

Background and purpose Prostanoid EP2 receptor agonists exhibit several activities including ocular hypotension, tocolysis and anti-inflammatory activity. This report describes the affinity and selectivity of a structurally novel, non-prostanoid EP2 receptor agonist, PGN-9856, and its therapeutic potential. Experimental approach The pharmacology of a series of non-prostanoid EP2 receptor agonists was determined according to functional and radioligand binding studies, mostly using human recombinant prostanoid receptor transfectants. The selectivity of PGN-9856, as the preferred compound, was subsequently determined by using a diverse variety of non-prostanoid target proteins. The therapeutic potential of PGN-9856 was addressed by determining its activity in relevant primate cell, tissue and disease models. Key results PGN-9856 was a selective and high affinity (pKi ≥ 8.3) ligand at human recombinant EP2 receptors. In addition to high affinity binding, it was a potent and full EP2 receptor agonist with a high level of selectivity at EP1 , EP3 , EP4 , DP, FP, IP and TP receptors. In cells overexpressing human recombinant EP2 receptors, PGN-9856 displayed a potency (pEC50 ≥ 8.5) and a maximal response (increase in cAMP) comparable to that of the endogenous agonist PGE2 . PGN-9856 exhibited no appreciable affinity (up 10 μM) for a range of 53 other receptors, ion channels and enzymes. Finally, PGN-9856 exhibited tocolytic, anti-inflammatory and long-acting ocular hypotensive properties consistent with its potent EP2 receptor agonist properties. Conclusions and implications PGN-9856 is a potent, selective and efficacious prostanoid EP2 receptor agonist with diverse potential therapeutic applications: tocolytic, anti-inflammatory and notably anti-glaucoma.

Outflow facility is a measurement of the ease in which aqueous humor flows out of the anterior chamber through the primary resistance tract of the trabecular meshwork. Tonography is an adapted procedure of tonometry in which intraocular pressure (IOP) is measured before, during and after applying a weight to the eye, yielding an outflow facility value in μL/min/mm Hg. Ocular rigidity, and pseudofacility impact tonography and interpretation of outflow facility measurements. The tonography method has numerous assumptions and limitations, but it remains a key research tool to measure outflow facility and analyze aqueous humor dynamics. Tonography helps understand how IOP is maintained in the healthy eye and how it is altered in disease states such as glaucoma. This review discusses the development, principles and practice of tonography in addition to the instruments used in tonography.

Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings.

Purpose To explore the demographic and clinical variables associated with intraocular pressure (IOP) lowering after cataract extraction (CE) alone or CE in combination with the iStent (Glaukos Corporation) placement (CE+IS). Design Retrospective data extraction and survival analysis of consecutive patients identified over a 2-year period. Participants Patients with mild to moderate glaucoma who underwent CE (48 eyes of 32 patients) or CE+IS (61 eyes of 37 patients) were analyzed. Methods Inability to reduce the number of medications or the IOP by at least 20% compared with baseline on 2 consecutive visits was considered surgical failure. Using Cox proportional hazards models, survival analysis was performed, and demographic and clinical variables were evaluated as risk factors. Main Outcome Measures Time to failure after surgical procedure. Results CE+IS had lower odds of failure than CE alone (hazard ratio [HR], 2.01; P = 0.047). In White patients, CE+IS showed greater odds of success compared with CE alone (HR, 2.86; P = 0.007). For non-White patients, no difference was found in the outcomes for the 2 procedures (HR, 0.59; P = 0.48). In the multivariate analysis, non-White race (HR, 8.75; P = 0.0002) and longer axial length (HR, 1.61; P = 0.03) were associated with greater hazard of failure after CE+IS. In the CE group, greater odds of failure were associated with steeper corneal curvature (HR, 1.74; P = 0.008), shallower anterior chamber (HR, 0.22; P = 0.008), and longer axial length (HR, 1.58; P = 0.01). Conclusions Addition of the iStent to CE improved the duration of IOP lowering in White patients, but not in non-White patients. Associations between IOP lowering after CE and biometric parameters may allow for leveraging these clinical parameters for better case selection for these procedures.

To investigate the mechanism of the intraocular pressure (IOP)-lowering effect of a novel selective prostaglandin E2 receptor 2 (EP2) receptor agonist, omidenepag isopropyl (OMDI).The effect of OMDI on IOP and aqueous humor dynamics was evaluated in cynomolgus monkeys with unilateral laser-induced ocular hypertension. In a crossover manner, the hypertensive eye of each monkey was dosed once daily with 20 μL of either 0.002% OMDI or vehicle. On day 7 of dosing, IOP was measured by pneumatonometry, aqueous humor flow and outflow facility were evaluated by fluorophotometry, and uveoscleral outflow was calculated mathematically. Treatments were compared by paired t-tests.OMDI at 0.002% significantly lowered IOP by 27%, 35%, and 44% at 0.5, 1.5, and 4 h after the last dosing, respectively. There was no difference in aqueous humor flow between vehicle and OMDI treatments. When comparing OMDI to the vehicle treatment, outflow facility and uveoscleral outflow were significantly (P 0.05) increased by 71% and 176%, respectively.OMDI, a novel IOP-lowering compound, reduced IOP by increasing outflow facility and uveoscleral outflow in nonhuman primates.

Glaucoma is a chronic, progressive, and debilitating optic neuropathy that causes retinal damage and visual defects. The pathophysiologic mechanisms of glaucoma remain ill-defined, and there is an indisputable need for contributions from basic science researchers in defining pathways for translational research. However, glaucoma researchers today face significant challenges due to the lack of a map of integrated pathways from bench to bedside and the lack of consensus statements to guide in choosing the right research questions, techniques, and model systems. Here, we present the case for the development of such maps and consensus statements, which are critical for faster development of the most efficacious glaucoma therapy. We underscore that interrogating the preclinical path of both successful and unsuccessful clinical programs is essential to defining future research. One aspect of this is evaluation of available preclinical research tools. To begin this process, we highlight the utility of currently available animal models for glaucoma and emphasize that there is a particular need for models of glaucoma with normal intraocular pressure. In addition, we outline a series of discoveries from cell-based, animal, and translational research that begin to reveal a map of glaucoma from cell biology to physiology to disease pathology. Completion of these maps requires input and consensus from the global glaucoma research community. This article sets the stage by outlining various approaches to such a consensus. Together, these efforts will help accelerate basic science research, leading to discoveries with significant clinical impact for people with glaucoma.

Purpose This study was designed to evaluate the changes in aqueous humor dynamics (AHD) produced by selective laser trabeculoplasty (SLT) and to explore if baseline AHD parameters are predictive of IOP response to SLT. Methods Thirty-one consecutive subjects diagnosed with ocular hypertension or primary open-angle glaucoma scheduled to undergo SLT as their primary IOP-lowering therapy were enrolled in this prospective observational study. Subjects underwent baseline assessment of AHD in both eyes. Variables assessed were IOPs at 9 AM and noon, aqueous humor flow rate (fluorophotometry), episcleral venous pressure (EVP, venomanometry), outflow facility (pneumatonography and fluorophotometry) and uveoscleral outflow (calculated using modified Goldmann equation). All subjects underwent 360 degrees SLT and AHD measurements were repeated 3 months later. Results Compared with baseline, IOPs after SLT were significantly lower at 9 AM (22.9 ± 5.1 vs. 19.7 ± 3.0 mm Hg; P = 0.001) and noon (23.4 ± 4.6 vs. 20.0 ± 3.5 mm Hg; P < 0.001). Outflow facility by fluorophotometry was significantly increased from 0.17 ± 0.11 μL/min/mm Hg at baseline to 0.24 ± 0.14 μL/min/mm Hg at 3 months (P = 0.008). Outflow facility by tonography (baseline: 0.16 ± 0.07 μL/min/mm Hg vs. 3 months: 0.22 ± 0.16 μL/min/mm Hg; P = 0.046) was similarly increased. No change in aqueous flow or EVP was observed. There were no changes in IOP or AHD in the contralateral untreated eye. Using multiple linear regression models, higher baseline aqueous flow, lower baseline outflow facility, and possibly lower uvescleral outflow were associated with more IOP lowering with SLT. Conclusions The IOP-lowering effect of SLT is mediated through an increase in outflow facility. There is no contralateral effect. Higher aqueous flow and lower outflow facility may be predictive of better response to SLT.

Since all prostanoid receptors affect intraocular pressure (IOP) and endogenous prostanoids are found in ocular tissues, the pressor effects of prostanoid antagonists were comprehensively evaluated. The absence of effects of most of these antagonists was not entirely anticipated. To ensure no false-negative results, ocular biodisposition studies were conducted.Monkeys with laser-induced ocular hypertension were used to study antagonist effects on IOP. Ocular biodisposition of each antagonist was assessed in rabbits, with LC/MS/MS analyses of tissue extracts and blood.EPThese antagonist studies provided no evidence for individual endogenous prostanoids exerting a meaningful role in regulating IOP. They do reaffirm the critical importance of studying ocular bioavailability for confirming negative data. Large differences among the antagonists in anterior segment and even ocular surface tissue biodisposition were observed in rabbits. It appears from these monkey studies, supported by rabbit ocular bioavailability data, that an absence of drug effect in the eye cannot be adequately substantiated without determination of ocular pharmacokinetics.

For2 decades, EP

Primary open angle glaucoma (POAG) is an optic neuropathy and an irreversible blinding disease. The etiology of glaucoma is not known but numerous risk factors are associated with this disease including aging, elevated intraocular pressure (IOP), race, myopia, family history and use of steroids. In POAG, the resistance to the aqueous humor drainage is increased leading to elevated IOP. Lowering the resistance and ultimately the IOP has been the only way to slow disease progression and prevent vision loss. The primary drainage pathway comprising of the trabecular meshwork (TM) is made up of relatively large porous beams surrounded by extracellular matrix (ECM). Its juxtacanalicular tissue (JCT) or the cribriform meshwork is made up of cells embedded in dense ECM. The JCT is considered to offer the major resistance to the aqueous humor outflow. This layer is adjacent to the endothelial cells forming Schlemm's canal, which provides approximately 10% of the outflow resistance. The ECM in the TM and the JCT undergoes continual remodeling to maintain normal resistance to aqueous humor outflow. It is believed that the TM is a major contributor of ECM proteins and evidence points towards increased ECM deposition in the outflow pathway in POAG. It is not clear how and from where the ECM components emerge to hinder the normal aqueous humor drainage. This review focuses on the involvement of the ECM in ocular hypertension and glaucoma and the mechanisms by which various ocular hypotensive drugs, both current and emerging, target ECM production, remodeling, and deposition.

Introduction: In the age of micro invasive /minimally invasive glaucoma surgery (MIGS), numerous glaucoma drainage devices are gaining importance. Hydrus is the latest device undergoing FDA approved clinical trials and is showing promising results in terms of intraocular pressure reduction in mild to moderate glaucoma when combined with cataract surgery.Areas covered: This review provides a detailed discussion of the preclinical and clinical trials of the Hydrus Microstent. A brief description of other new Schlemm’s canal based surgical procedures is also provided. An extensive literature search was made using the following keywords; Hydrus, Microstent, Schlemm’s canal scaffold, MIGS and outflow facility. Information on active clinical trials was obtained from clinicaltrails.gov. Recent and ongoing research activities on MIGS were obtained from abstracts presented at ARVO and AAO in recent years.Expert commentary: Hydrus microstent bypasses the trabecular meshwork and dilates a part of the Schlemm...

Primary open-angle glaucoma (POAG) is a multifactorial optic neuropathy characterized by progressive retinal ganglion cell death and visual field loss. Some speculate that sex plays a role in the risk of developing POAG and that the physiological differences between men and women may be attributed to the variable effects of sex hormones on intraocular pressure, ocular blood flow, and/or neuroprotection. Estrogen, in the form of premenopausal status, pregnancy, and postmenopausal hormone therapy is associated with an increase in ocular blood flow, decrease in intraocular pressure and neuroprotective properties. The vasodilation caused by estrogen and its effects on aqueous humor outflow may contribute. In contrast, although testosterone may have known effects in the cardiovascular and cerebrovascular systems, there is no consensus as to its effects in ocular health or POAG. With a better understanding of sex hormones in POAG, sex hormone-derived preventative and therapeutic considerations in disease management may provide for improved sex-specific patient care.

Canine glaucoma is a group of disorders that are generally associated with increased intraocular pressure (IOP) resulting in a characteristic optic neuropathy. Glaucoma is a leading cause of irreversible vision loss in dogs and may be either primary or secondary. Despite the growing spectrum of medical and surgical therapies, there is no cure, and many affected dogs go blind. Often eyes are enucleated because of painfully high, uncontrollable IOP. While progressive vision loss due to primary glaucoma is considered preventable in some humans, this is mostly not true for dogs. There is an urgent need for more effective, affordable treatment options. Because newly developed glaucoma medications are emerging at a very slow rate and may not be effective in dogs, work toward improving surgical options may be the most rewarding approach in the near term. This Viewpoint Article summarizes the discussions and recommended research strategies of both a Think Tank and a Consortium focused on the development of more effective therapies for canine glaucoma; both were organized and funded by the American College of Veterinary Ophthalmologists Vision for Animals Foundation (ACVO‐VAF). The recommendations consist of (a) better understanding of disease mechanisms, (b) early glaucoma diagnosis and disease staging, (c) optimization of IOP‐lowering medical treatment, (d) new surgical therapies to control IOP, and (e) novel treatment strategies, such as gene and stem cell therapies, neuroprotection, and neuroregeneration. In order to address these needs, increases in research funding specifically focused on canine glaucoma are necessary.

Cultured trabecular meshwork (TM) cells are a valuable model system to study the cellular mechanisms involved in the regulation of conventional outflow resistance and thus intraocular pressure; and their dysfunction resulting in ocular hypertension. In this review, we describe the standard procedures used for the isolation of TM cells from several animal species including humans, and the methods used to validate their identity. Having a set of standard practices for TM cells will increase the scientific rigor when used as a model, and enable other researchers to replicate and build upon previous findings.

This protocol provides a step-by-step guide to shotgun sphingolipid analysis of aqueous humor. We describe the Bligh and Dyer crude lipid extraction method and electrospray ionization tandem mass spectrometry (ESI-MS/MS) coupled with MZmine 2.21 data processing for identification and ratiometric quantitation of sphingosine, sphingosine-1-phosphate, sphingomyelin, and ceramide.

iTRAQ 4plex method enables multiplexing of up to four samples for simultaneous quantitation to improve sensitivity and scope of proteomic analysis. Here, we describe iTRAQ 4plex labeling of human aqueous humor specimens followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and data analysis for peptide identification and quantitation using Proteome Discoverer software. The protocol can be applied for other animals as well; however, pooling of specimens may be required to obtain sufficient amount of protein for labeling.

Glaucoma, where the retinal ganglion cells (RGCs) carrying the visual signals from the retina to the visual centers in the brain are progressively lost, is the most common cause of irreversible blindness. The management approaches, whether surgical, pharmacological, or neuroprotective do not reverse the degenerative changes. The stem cell approach to replace dead RGCs is a viable option but currently faces several barriers, such as the lack of a renewable, safe, and ethical source of RGCs that are functional and could establish contacts with bona fide targets. To address these barriers, we have derived RGCs from the easily accessible adult limbal cells, reprogrammed to pluripotency by a non-nucleic acid approach, thus circumventing the risk of insertional mutagenesis. The generation of RGCs from the induced pluripotent stem (iPS) cells, also accomplished non-cell autonomously, recapitulated the developmental mechanism, ensuring the predictability and stability of the acquired phenotype, comparable to that of native RGCs at biochemical, molecular, and functional levels. More importantly, the induced RGCs expressed axonal guidance molecules and demonstrated the potential to establish contacts with specific targets. Furthermore, when transplanted in the rat model of ocular hypertension, these cells incorporated into the host RGC layer and expressed RGC-specific markers. Transplantation of these cells in immune-deficient mice did not produce tumors. Together, our results posit retinal progenitors generated from non-nucleic acid-derived iPS cells as a safe and robust source of RGCs for replacing dead RGCs in glaucoma. Stem Cells 2013;33:1743–1758

Purpose: To investigate the changes in intraocular pressure (IOP), aqueous flow, and outflow facility, as well as efficacy of IOP-lowering drugs before and after sexual development in rabbits. Methods: Male Dutch-belted rabbits were studied at night between the ages of 8 and 44 weeks. During these times, body weight, testicular volume, and serum testosterone were measured to monitor sexual maturity. Ocular measurements included anterior chamber depth, central corneal thickness, IOP, aqueous flow, and outflow facility. Systemic acetazolamide or topical timolol, latanoprost, or saline were administered pre- and postpuberty to assess drug effects on these parameters. Results: Body weight, testicular volume, and serum testosterone increased until 28 weeks of age. IOP increased during prepuberty (R(2) = 0.49, P = 0.003), dropped significantly during puberty, rising again immediate postpuberty, and changing little thereafter. Postpuberty compared with prepuberty found higher IOP (P

Purpose It is not known if outflow facilities measured by pneumatonography and Schiotz tonography are interchangeable. In this study we compared outflow facility measured by pneumatonography to outflow facility measured by digital Schiotz tonography. Methods Fifty-six eyes from 28 healthy participants, ages 41 to 68 years, were included. Intraocular pressure (IOP) was measured in the sitting and supine positions with a pneumatonometer. With the subject in the supine position, IOP was recorded for 2 minutes by using a pneumatonometer with a 10-g weight and for 4 minutes by using a custom digital Schiotz tonometer. Outflow facility was determined from the changes in pressure and intraocular volume and a standard assumed ocular rigidity coefficient for each instrument, respectively, and by using an ocular rigidity coefficient calculated by measuring pressure without and with a weight added to the pneumatonometer tip. Results The outflow facility was 0.29 ± 0.09 μL/min/mm Hg by Schiotz tonography and 0.24 ± 0.08 μL/min/mm Hg by pneumatonography (P < 0.001) when using the standard assumed constant ocular rigidity coefficient. Mean calculated ocular rigidity coefficient was 0.028 ± 0.01 μL-1, and outflow facility determined by using this coefficient was 0.23 ± 0.08 μL/min/mm Hg by Schiotz tonography and 0.21 ± 0.07 μL/min/mm Hg by pneumatonography (P = 0.003). Outflow facilities measured by the two devices were correlated when the ocular rigidity was assumed (r = 0.60, P < 0.001) or calculated (r = 0.70, P < 0.001). Conclusions Outflow facilities measured by pneumatonography were correlated with those measured by Schiotz tonography, but Schiotz tonography reported approximately 10% to 20% higher facilities when using the standard method. When ocular rigidity was determined for each eye, differences were smaller. Measurements from these devices cannot be compared directly.

This study evaluates ocular biometrics and aqueous humour dynamics (AHD) in healthy Chinese volunteers to determine how the various ocular parameters interact to maintain physiological intraocular pressure (IOP) at all ages.Sixty-nine volunteers enrolled in this cross-sectional study and were categorised into young (20-30 years) and old (≥50 years) groups. Measurements included IOP, ocular biometrics and AHD. Data were analysed using mixed model with random sampling to account for both eyes from the same individual. Spearman's rank correlation with bootstrap resampling was used to find associations between parameters.Compared with young subjects, old subjects had significantly (p0.05) thinner corneas (CCT; 549.7±5.7 vs 530.6±5.3 µm; mean±SEM), shallower anterior chambers (3.14±0.05 vs 2.37±0.05 mm) and slower aqueous flow (Fa; 3.0±0.1 vs 2.7±0.1 µL/min). Uveoscleral outflow slowed (Fu; 1.0±0.2 vs 0.7±0.1) but not significantly. A positive linear association between IOP and episcleral venous pressure was found (young: RIn the healthy ageing Chinese eye, IOP remains unchanged, while Fa slows, which is counterbalanced by slowing of Fu. Aqueous humour exits the eye preferentially through the trabecular route at all ages. Ageing is also associated with shallowing of the anterior chamber and thinning of the cornea. A slower Fa with lower outflow facility supports existence of autoregulatory mechanisms.

BackgroundGlaucoma prevalence and subtype profile vary across different racial and ethnic groups. This study provides a comparative evaluation of differences in aqueous humour dynamics (AHD) and ocular biometrics in healthy Chinese and Caucasian adults of two different age groups.MethodsData from two independent studies with identical designs were compared. Cohorts included young adults (20–30 years old, 32 Chinese and 39 Caucasians) and older adults (>50 years old, 37 Chinese and 46 Caucasians). Parameters of AHD and ocular biometrics were evaluated. Group comparisons were made by generalised estimating equation methods.ResultsDifferences in young adult Caucasians compared with similarly aged Chinese were thinner central cornea (−29.27 µm, pConclusionDifferences in AHD and biometrics between Caucasian and Chinese adults include larger ACVs which may contribute to the wider angles reported in Caucasians, and slower Fa rates coupled with faster Fu rates which may contribute to their lower IOP and lower overall risk of glaucoma.

Optic nerve and retinal diseases such as glaucoma, age-related macular degeneration (AMD) and retinitis pigmentosa (RP) are significant public health concerns and have a momentous impact on patients' functional status and quality of life. These diseases are among the most common causes of visual impairment worldwide and account for billions of dollars in healthcare expenditures and lost productivity. The importance of adequate treatment of these conditions and the need for efficacious therapeutic drugs cannot be overstated. Unoprostone continues to be developed as a potential treatment for these debilitating diseases.This review provides background information on unoprostone isopropyl (unoprostone), a prostanoid and synthetic docosanoid approved for the treatment of open-angle glaucoma and ocular hypertension, and recapitulates safety and efficacy data as it relates to this indication. Additionally, this review describes potential new uses of unoprostone as therapy for dry AMD and RP. A literature search of peer-reviewed publications was performed utilizing PubMed. Searches were last updated on 10 September 2012.Current data indicate that unoprostone does significantly lower intraocular pressure (IOP) and has a favorable safety and tolerability profile. However, the IOP-lowering effects of unoprostone do not compare with other commercially available prostanoids and it has the disadvantage of a twice-daily rather than once-daily dosing regimen. Nonetheless, recent data suggest that unoprostone may improve neuronal survival and increase ocular blood flow, indicating that it may have some value as a therapy for glaucoma, RP and dry AMD. Further studies are needed to confirm whether unoprostone provides any clinically significant advantage over the other commercially available prostanoids.

This study examines the effects of 2 Rho kinase inhibitors on intraocular pressure (IOP) and aqueous humor dynamics.IOPs of New Zealand albino rabbits with ocular normotension and cynomolgus macaques (nonhuman primate, NHP) with chronic unilateral laser-induced glaucoma were measured at baseline and periodically after a 9 a.m. dose of H-1152, Y-27632, or vehicle. In a separate group of NHPs, aqueous flow, outflow facility, uveoscleral outflow, and IOP were determined after treatment with Y-27632 or vehicle control.Decreases in IOP were found in rabbits (n = 5) at 6 h after one dose of 2% Y-27632 (29%, P = 0.0002) or 1% H-1152 (35%, P = 0.0001), and in hypertensive eyes of NHPs (n = 7-9) at 3 h after one dose of 2% Y-27632 (35%, P = 0.005) or 1% H-1152 (51%, P = 0.0003). With 2 doses of 1% Y-27632 or vehicle in NHP hypertensive eyes (n = 12), significant drug effects were IOP reduction of 28% (P = 0.05) at 2.5 h after the second dose and increases in aqueous flow (36%; P = 0.013), uveoscleral outflow (59%, P = 0.008), and outflow facility (40%; P = 0.01). In normotensive eyes of the same animals, aqueous flow increased by 21% (P = 0.03). No significant change was found in any of the other parameters.Y-27632 and H-1152 lower IOP in rabbits and hypertensive eyes of NHPs for at least 6 h after single doses. The Y-27632 effect on IOP in hypertensive NHP eyes is caused by increases in outflow facility and uveoscleral outflow. An increase in aqueous humor formation attenuates but does not prevent an IOP decrease.

This study evaluates aqueous humor dynamics in rhesus monkeys from the University of Florida inbred colony with ocular normotension and naturally occurring ocular hypertension. Eight monkeys with untreated intraocular pressures (IOPs) of less than 18 mmHg in one eye (ONT group) and seven with untreated IOPs of greater than or equal to 18 mmHg in one eye (OHT group) were included in the study. Assessments included central cornea thickness by ultrasound pachymetry, IOP by tonometry, aqueous flow and outflow facility by fluorophotometry, and uveoscleral outflow by mathematical calculation. Animals were sedated with ketamine for all measurements. Values from the two eyes of each animal were averaged, with the exception of one animal that had only one good eye. Comparisons between groups were made by Student's two-tailed unpaired t-tests. Compared to the ONT group, the OHT group had higher IOPs at all times measured (4:00 PM the day before the study, 21.2 ± 6.5 versus 14.4 ± 1.5 mmHg, p = 0.01; 9:00 AM the day of the study, 20.7 ± 6.6 versus 14.8 ± 1.2 mmHg, p = 0.03; 11:00 AM the day of the study, 16.0 ± 1.6 versus 13.3 ± 2.9 mmHg, p = 0.05) and lower aqueous flow (2.12 ± 0.40 versus 4.54 ± 1.11 μl/min, p = 0.0001), outflow facility (0.17 ± 0.10 versus 0.33 ± 0.07 μl/min/mmHg, p = 0.01) and uveoscleral outflow (p < 0.05). The elevated IOP in inbred Florida rhesus monkeys is a result of significantly reduced outflow facility and uveoscleral outflow. These animals also have slower aqueous flow than the ONT animals which does not contribute to the higher IOP.

The study of aqueous humor dynamics (AHD) in mice is becoming more prevalent as more strains with elevated intraocular pressure (IOP) are developed. High IOP is usually associated with reduced outflow facility making this one of the more important AHD parameters to evaluate. Ocular measurements in mice require anesthesia that has profound effects on IOP but unknown effects on outflow facility. This study evaluates the effects of anesthesia duration and latanoprost treatment on outflow facility and IOP in BALB/c mice.IOPs were measured in conscious and anesthetized mice by tonometry. Outflow facility was evaluated in 15-min intervals at three pressure levels over two 45-min periods. Comparisons were made between latanoprost-treated eyes and untreated contralateral eyes. To determine the effect of anesthesia duration on IOP, a microneedle method was used to follow IOP for 120 min in separate mice.IOP was 9.7 +/- 0.3 mmHg (mean +/- SEM) in conscious mice and 7.1 +/- 0.02 within 10 min of anesthesia initiation (p0.01). IOP changed significantly between but not within assessment periods. IOP at 75 min was significantly (p = 0.004) reduced compared to IOP at 15 min after initial anesthesia. In control eyes, outflow facility did not change between the two 45-min assessment periods during the 120 min test (p = 0.80). In latanoprost-treated eyes, outflow facility increased compared with control eyes during both assessment periods (p = 0.03). A test of filters in series with known resistance found that the method was sensitive enough to detect a change in outflow facility of 0.001 microl/min/mmHg.Administration of ketamine/xylazine anesthesia for 120 min did not alter outflow facility or lessen the effect of latanoprost on outflow facility in mice as determined by a new analysis system. Accurate IOP measurements must be made within minutes of anesthesia administration but outflow facility measurements can be made with less haste.

To investigate whether the intraocular pressure (IOP) reduction and mechanism of action of timolol and latanoprost change between 1 and 6 weeks of treatment.Thirty participants on no ocular medications completed this double-masked, 6-visit, crossover study. At each visit IOP was determined by pneumatonometry, aqueous flow by fluorophotometry, and outflow facility by fluorophotometry and tonography. Separate values of uveoscleral outflow were calculated using the Goldmann equation, an episcleral venous pressure of 11 mm Hg, and each of the 2 outflow facility values. In a randomized fashion, both eyes were treated for 6 weeks with latanoprost 0.005% once daily or timolol 0.5% twice daily. Measurements were repeated at 1 and 6 weeks of dosing. After 6 weeks of washout, the second drug was administered in a crossover manner. One and 6 weeks of treatment were compared with appropriate baselines using 1-way analyses of variance (ANOVA).Timolol reduced aqueous flow by 27% at week 1 (P0.001) and 16% at week 6 (P=0.03). Latanoprost increased uveoscleral outflow several fold at each visit (P0.05). Neither drug altered outflow facility. Neither drug showed a detectable change in aqueous humor dynamics at week 6 compared with week 1. Both drugs significantly (P0.001) reduced IOP at 1 and 6 weeks of treatment.Timolol and latanoprost significantly reduce IOP by different mechanisms. Timolol reduces aqueous flow whereas latanoprost increases uveoscleral outflow. Continued treatment with timolol or latanoprost for 6 weeks did not alter effects on aqueous humor dynamics. Outflow facility changes sometimes reported with prostaglandin analogues were not detected in this study.

Nitric oxide (NO) is involved in a variety of physiological processes including ocular aqueous humor dynamics by targeting mechanisms that are complementary to those of prostaglandins. Here, we have characterized a newly synthesized compound, NCX 125, comprising latanoprost acid and NO-donating moieties.NCX 125 was synthesized and tested in vitro for its ability to release functionally active NO and then compared with core latanoprost for its intraocular pressure (IOP)-lowering effects in rabbit, dog, and nonhuman primate models of glaucoma.NCX 125 elicited cGMP formation (EC(50) = 3.8 + or - 1.0 microM) in PC12 cells and exerted NO-dependent iNOS inhibition (IC(50) = 55 + or - 11 microM) in RAW 264.7 macrophages. NCX 125 lowered IOP to a greater extent compared with equimolar latanoprost in: (a) rabbit model of transient ocular hypertension (0.030% latanoprost, not effective; 0.039% NCX 125, Delta(max) = -10.6 + or - 2.3 mm Hg), (b) ocular hypertensive glaucomatous dogs (0.030% latanoprost, Delta(max)= -6.7 + or - 1.2 mm Hg; 0.039% NCX 125, Delta(max) = -9.1 + or - 3.1 mm Hg), and (c) laser-induced ocular hypertensive non-human primates (0.10% latanoprost, Delta(max) = -11.9 + or - 3.7 mm Hg, 0.13% NCX 125, Delta(max) = -16.7 + or - 2.2 mm Hg). In pharmacokinetic studies, NCX 125 and latanoprost resulted in similar latanoprost-free acid exposure in anterior segment ocular tissues.NCX 125, a compound targeting 2 different mechanisms, is endowed with potent ocular hypotensive effects. This may lead to potential new perspectives in the treatment of patients at risk of glaucoma.

This study investigated the relationship between decreased outflow facility (C) and changes in hydrodynamic aqueous humor outflow patterns and morphology in cynomolgus monkey eyes with unilateral chronically elevated intraocular pressure (IOP). Argon laser photocoagulation burns to the trabecular meshwork (TM) were made in one eye of each monkey (N = 3), leaving the contralateral eye as a normotensive control. IOPs were followed by pneumatonometry for 16-70 months. C was measured by fluorophotometry before sacrifice. To label the hydrodynamic patterns of outflow, the eyes were enucleated and perfused with fluorescent microspheres (0.5 microm; 0.002%) at the last pressure measured before death minus 7 mmHg. The eyes were perfusion-fixed at the same pressure. Confocal images were taken along the inner wall (IW) of the Schlemm's canal (SC). The total length (TL) and the filtration length (FL) of the IW decorated by tracers were measured in frontal sections. The average percent effective filtration length (PEFL = FL/TL) was calculated for each eye. Sections exhibiting SC were processed and examined under light and electron microscopy. The average IOP was significantly higher in laser-treated eyes (mean +/- SD = 61.33 +/- 4.16 mmHg) than controls (22.67 +/- 4.16 mmHg, P = 0.002). The average C was 13-fold lower in laser-treated eyes (0.03 +/- 0.02 microl/min/mmHg) than controls (0.39 +/- 0.17 microl/min/mmHg, P = 0.057). By confocal microscopy, in control eyes, SC was open and a segmental distribution of microspheres was found in the TM with a greater concentration near the collector channel (CC) ostia. Much less tracer labeling was seen along SC in laser-treated eyes than control eyes. The average PEFL in controls (47.47 +/- 10.79%) was 6-fold larger than in laser-treated eyes (8.40 +/- 4.81%, P = 0.048). The average distance between the inner and outer wall of SC was 5-fold greater in control eyes (18.99 +/- 6.03 microm) than in laser-treated eyes (3.47 +/- 0.33 microm, P = 0.048). By light microscopy, there was extensive pigmentation throughout the TM, denser extracellular matrix in the JCT region, and most of SC collapsed with focal herniations of the IW and JCT protruding into the CC ostia in laser-treated eyes. By electron microscopy, few or no microspheres were observed in laser-treated areas and the areas with SC collapse. More microspheres were observed near the CC ostia area in non-lasered areas. In conclusion, in the laser-induced glaucoma model, laser damage results in a reduction in the available area for outflow across the IW of SC which contributes to the decrease in C and thus elevation of the IOP. Constriction of SC, caused by the chronic elevation of IOP, further decreases the available area for outflow across the IW which decreases C even more in a vicious cycle. This study suggests that the available area for aqueous humor outflow across the IW of SC may play a role in regulating outflow resistance and maintaining IOP.

The aims of the current studies were to determine the in vitro and in vivo ocular and non-ocular pharmacological properties of cabergoline using well documented receptor binding, cell-based functional assays, and in vivo models. Cabergoline bound to native and/or human cloned serotonin-2A/B/C (5HT(2A/B/C)), 5HT(1A), 5HT(7), alpha(2B), and dopamine-2/3 (D(2/3)) receptor subtypes with nanomolar affinity. Cabergoline was an agonist at human recombinant 5HT(2), 5HT(1A) and D(2/3) receptors but an antagonist at 5HT(7) and alpha(2) receptors. In primary human ciliary muscle (h-CM) and trabecular meshwork (h-TM) cells, cabergoline stimulated phosphoinositide (PI) hydrolysis (EC(50)=19+/-7 nM in TM; 76 nM in h-CM) and intracellular Ca(2+) ([Ca(2+)](i)) mobilization (EC(50)=570+/-83 nM in h-TM; EC(50)=900+/-320 nM in h-CM). Cabergoline-induced [Ca(2+)](i) mobilization in h-TM and h-CM cells was potently antagonized by a 5HT(2A)-selective antagonist (M-100907, K(i)=0.29-0.53 nM). Cabergoline also stimulated [Ca(2+)](i) mobilization more potently via human cloned 5HT(2A) (EC(50)=63.4+/-10.3 nM) than via 5HT(2B) and 5HT(2C) receptors. In h-CM cells, cabergoline (1 microM) stimulated production of pro-matrix metalloproteinases-1 and -3 and synergized with forskolin to enhance cAMP production. Cabergoline (1 microM) perfused through anterior segments of porcine eyes caused a significant (27%) increase in outflow facility. Topically administered cabergoline (300-500 microg) in Dutch-belted rabbit eyes yielded 4.5 microMM and 1.97 microM levels in the aqueous humor 30 min and 90 min post-dose but failed to modulate intraocular pressure (IOP). However, cabergoline was an efficacious IOP-lowering agent in normotensive Brown Norway rats (25% IOP decrease with 6 microg at 4h post-dose) and in conscious ocular hypertensive cynomolgus monkeys (peak reduction of 30.6+/-3.6% with 50 microg at 3h post-dose; 30.4+/-4.5% with 500 microg at 7h post-dose). In ketamine-sedated monkeys, IOP was significantly lowered at 2.5h after the second topical ocular dose (300 microg) of cabergoline by 23% (p

PURPOSE To determine the effect of central corneal thickness (CCT) on the efficacy of intraocular pressure (IOP)-reducing drugs in patients with ocular hypertension (OHT). METHODS This retrospective study analyzed research records of 115 OHT patients and 97 ocular normotensive (ONT) volunteers. CCT was measured by slit-lamp pachymetry and IOP by pneumatonometry. The OHT patients were divided into Thick (>540 microm, n=52) and Thin (

PURPOSE The prostaglandin F2alpha (PGF2α) analogue bimatoprost lowers intraocular pressure (IOP) by increasing uveoscleral outflow at doses shown to elicit redness of the eye. With the aim to enhance the IOP-lowering effect of bimatoprost we studied NCX 470 [(S,E)-1-((1R,2R,3S,5R)-2-((Z)-7-(ethylamino)-7-oxohept-2-enyl)-3,5-dihydroxycyclopentyl)-5-phenylpent-1-en-3-yl 6-(nitrooxy)hexanoate], a dual-acting compound combining bimatoprost with nitric oxide (NO) known to mainly act via relaxation of trabecular meshwork and Schlemm's canal. METHODS New Zealand white rabbits with transient hypertonic saline-induced IOP elevation (tOHT-rabbits), cynomolgus monkeys with laser-induced ocular hypertension (OHT-monkeys), and normotensive dogs (ONT-dogs) were used. The levels of NCX 470, bimatoprost, and bimatoprost acid were determined in aqueous humor (AH), cornea (CR), and iris/ciliary body (ICB) by liquid chromatography-mass spectrometry/mass (LC-MS/MS), while cGMP in AH and ICB was monitored using an enzyme immunoassay (EIA) kit in pigmented Dutch Belted rabbits. RESULTS NCX 470 (0.14%, 30 μL) lowered IOP in tOHT-rabbits with an E(max) of -7.2 ± 2.8 mm Hg at 90 minutes. Bimatoprost at equimolar dose (0.1%, 30 μL) was noneffective in this model. NCX 470 (0.042%, 30 μL) was more effective than equimolar (0.03%, 30 μL) bimatoprost in ONT-dogs (IOP change, -5.4 ± 0.7 and -3.4 ± 0.7 mm Hg, respectively, P < 0.05) and in OHT-monkeys (IOP change, -7.7 ± 1.4 and -4.8 ± 1.7 mm Hg, respectively, P < 0.05) at 18 hours post dosing. NCX 470 (0.042%, 30 μL) or bimatoprost (0.03%, 30 μL) resulted in similar bimatoprost acid exposure in AH, CR, and ICB while cGMP was significantly increased in AH and ICB at 18 and 24 hours after NCX 470 dosing. CONCLUSIONS NCX 470 lowers IOP more than equimolar bimatoprost in three animal models of glaucoma by activating PGF2α and NO/cGMP signaling pathways.