Enhancing the structure-function relationship in glaucoma using anatomical compensation of retinal nerve fibre layer.

BACKGROUND/AIMS: To investigate whether compensating retinal nerve fibre layer (RNFL) thickness measurements for demographic and anatomical ocular factors can strengthen the structure-function relationship in patients with glaucoma. METHODS: 600 eyes from 412 patients with glaucoma (mean deviation of the visual field (MD VF) -6.53±5.55 dB) were included in this cross-sectional study. Participants underwent standard automated perimetry and spectral-domain optical coherence tomography imaging (Cirrus; Carl Zeiss Meditec). Compensated RNFL thickness was computed considering age, refractive error, optic disc parameters and retinal vessel density. The relationship between MD VF and RNFL thickness measurements, with or without demographic and anatomical compensation, was evaluated sectorally and focally. RESULTS: The superior arcuate sector exhibited the highest correlation between measured RNFL and MD VF, with a correlation of 0.49 (95% CI 0.37 to 0.59). Applying the compensated RNFL data increased the correlation substantially to 0.62 (95% CI 0.52 to 0.70; p<0.001). Only 61% of the VF locations showed a significant relationship (Spearman's correlation of at least 0.30) between structural and functional aspects using measured RNFL data, and this increased to 78% with compensated RNFL measurements. In the 10°-20° VF region, the slope below the breakpoint for compensated RNFL thickness demonstrated a more robust correlation (slope=1.66±0.18 µm/dB; p<0.001) than measured RNFL (slope=0.27±0.67 µm/dB; p=0.688). CONCLUSION: Compensated RNFL data improve the correlation between RNFL measurements and VF parameters. This indicates that creating structure-to-function maps that consider anatomical variances may aid in identifying localised structural and functional loss in glaucoma.

Three-year Outcomes of an Expanded Asynchronous Virtual Glaucoma Clinic in Singapore.

PURPOSE: Virtual glaucoma clinics can help increase health care capacity, easing the disease burden of glaucoma. This study assesses the safety, rate of glaucoma progression, time efficiency, and cost-savings of our expanded Glaucoma Observation Clinic (GLOC) at the Singapore National Eye Centre over 3 years. METHODS: All patients seen at GLOC between July 2018 and June 2021 were included. Visual acuity, intraocular pressure, and visual fields or optic nerve head imaging were recorded, followed by a virtual review of the data by an ophthalmologist. An objective review of the management of 100 patients was conducted by 2 senior consultants independently as a safety audit. Patient outcomes including the rate of instability (due to worsening of clinical parameters necessitating a conventional clinic visit), glaucoma progression, the consultation review time efficiency, and cost-savings of GLOC were measured. RESULTS: Of 3458 patients, 16% had glaucoma, and the others had risk factors for glaucoma. The safety audit demonstrated a 95% interobserver agreement. The rate of instability was 14.6%, of which true progression was observed in 3.12%. The time taken for a glaucoma specialist to review a GLOC patient was 5.75±0.75 minutes compared with 13.7±2.3 minutes in a conventional clinic. The per capita manpower cost per GLOC patient per visit was $36.77 compared with $65.62 in the conventional clinic. This translates to a cost-saving of $280.65 over the lifetime of a hypothetical patient. CONCLUSIONS: Our expanded virtual glaucoma clinic is a safe, time-efficient, and cost-effective model with low rates of glaucoma progression, which could allow for significant health care capacity expansion.

Handheld chromatic pupillometry can reliably detect functional glaucomatous damage in eyes with high myopia.

BACKGROUND/AIMS: To assess pupillary light responses (PLRs) in eyes with high myopia (HM) and evaluate the ability of handheld chromatic pupillometry (HCP) to identify glaucomatous functional loss in eyes with HM. METHODS: This prospective, cross-sectional study included 28 emmetropes (EM), 24 high myopes without glaucoma (HM) and 17 high myopes with confirmed glaucoma (HMG), recruited at the Singapore National Eye Center. Monocular PLRs were evaluated using a custom-built handheld pupillometer that recorded changes in horizontal pupil radius in response to 9 s of exponentially increasing blue (469.1 nm) and red (640.1 nm) lights. Fifteen pupillometric features were compared between groups. A logistic regression model (LRM) was used to distinguish HMG eyes from non-glaucomatous eyes (EM and HM). RESULTS: All pupillometric features were similar between EM and HM groups. Phasic constriction to blue (p<0.001) and red (p=0.006) lights, and maximum constriction to blue light (p<0.001) were reduced in HMG compared with EM and HM. Pupillometric features of melanopsin function (postillumination pupillary response, PIPR area under the curve (AUC) 0-12 s (p<0.001) and PIPR 6 s (p=0.01) to blue light) were reduced in HMG. Using only three pupillometric features, the LRM could classify glaucomatous from non-glaucomatous eyes with an AUC of 0.89 (95% CI 0.77 to 1.00), sensitivity 94.1% (95% CI 82.4% to 100.0%) and specificity 78.8% (95% CI 67.3% to 90.4%). CONCLUSION: PLRs to ramping-up light stimuli are unaltered in highly myopic eyes without other diagnosed ocular conditions. Conversely, HCP can distinguish glaucomatous functional loss in eyes with HM and can be a useful tool to detect/confirm the presence of glaucoma in patients with HM.

Oral Ibuprofen is Associated With Reduced Likelihood of Early Bleb Failure After Trabeculectomy in High-Risk Glaucoma Patients.

PRCIS: Individuals prescribed ibuprofen after trabeculectomy have better postoperative intraocular pressure (IOP) control and a higher chance of bleb survival despite being at a higher risk of scarring. PURPOSE: To investigate the effects of early adjunctive oral ibuprofen treatment on IOP and bleb failure in eyes at high risk of scarring. METHODS: In these retrospective analyses, 288 eyes of 273 patients (mean ± SD age: 68.56 ± 10.47 y; 32.60% females) with primary glaucoma who underwent trabeculectomy/phacotrabeculectomy at the Singapore National Eye Centre between April 2020 and April 2021 with a follow-up duration ≥1 year were included. Of these, 77 (26.7%) eyes deemed to be at high risk of scarring were administered oral ibuprofen ≥3 months postoperatively (mean ± SD ibuprofen administration duration: 4.08 ± 2.28 wk). Participant's IOPs at baseline and at postoperative weeks 1, 2-3; and months 1, 2, 3, 6, and 12 were recorded. Bleb failure was defined as 2 consecutive IOP readings of >21, >18, and >15 mm Hg, and/or requiring remedial postoperative laser or surgery. RESULTS: The ibuprofen group experienced significantly greater postoperative IOP reductions at week 1 [mean difference, 95%CI: -2.89 (-5.22, -0.56) mm Hg] and month 1 [-2.29 (-4.53, -0.05) mm Hg]; and substantially lower odds of bleb failure at the >18 mm Hg [odds ratio, 95% CI: 0.39 (0.20-0.79)] and >15 mm Hg [0.52 (0.29-0.94)] thresholds, compared with the non-ibuprofen group. No differences in adverse ocular hypotony events were observed. CONCLUSION: Early adjunctive oral ibuprofen administered to individuals at high risk of posttrabeculectomy scarring is associated with greater IOP reductions and reduced likelihood of bleb failure. Our results suggest that oral nonsteroidal anti-inflammatory drugs may be a safe way of improving trabeculectomy survival in high-risk eyes.

Evaluation of a steroid delivery system to mitigate the severity of proliferative vitreoretinopathy in a minipig model.

Purpose: To investigate the efficacy of liposomal prednisolone phosphate to mitigate the severity of proliferative vitreoretinopathy (PVR) in a minipig model of PVR. Methods: A total of 18 eyes of 9 minipigs underwent PVR induction surgically. Eyes were randomized equally into three groups: intravitreal injection of liposomal prednisolone phosphate (LPP), triamcinolone acetonide (TA), and controls. PVR severity was graded on fundoscopic examination using a modified version of the Silicon Study Classification System. Severe PVR was defined as grade 2-5 on this classification, and the proportion of eyes with retinal detachment from severe PVR, defined as retinal re-detachment, i.e., PVR grade 2-5, was compared between treatment and control groups. Results: On day 28, five eyes (83.3%) in the control group were observed to have severe PVR. Within the LPP group, one (16.7%) eye developed retinal detachment due to severe PVR. Grade 0 PVR was observed in four (66.7%) eyes, grade 1 in one (16.7%) eye, and grade 5 in one (16.7%) eye. Within the TA group, grade 0 PVR was observed in four eyes (66.7%), grade 1 in two eyes (16.6%), and grade 5 in one (16.7%) eye. The difference in the proportion of eyes with severe PVR was significantly lower in the LPP group compared to controls at day 28 (16.7% vs 83.3%, p=0.02). There was no significant difference in the rate of severe PVR or median PVR grade between the liposomal prednisolone phosphate and triamcinolone acetonide groups. Conclusion: Liposomal prednisolone phosphate reduces the severity of PVR in a minipig model of PVR.

The development of a glaucoma-specific health-related quality of life item bank supporting a novel computerized adaptive testing system in Asia.

BACKGROUND: A glaucoma-specific health-related quality of life (HRQoL) item bank (IB) and computerized adaptive testing (CAT) system relevant to Asian populations is not currently available. We aimed to develop content for an IB focusing on HRQoL domains important to Asian people with glaucoma; and to compare the content coverage of our new instrument with established glaucoma-specific instruments. METHODS: In this qualitative study of glaucoma patients recruited from the Singapore National Eye Centre (November 2018-November 2019), items/domains were generated from: (1) glaucoma-specific questionnaires; (2) published articles; (3) focus groups/semi-structured interviews with glaucoma patients (n = 27); and (4) feedback from glaucoma experts. Data were analyzed using the constant comparative method. Items were systematically refined to a concise set, and pre-tested using cognitive interviews with 27 additional glaucoma patients. RESULTS: Of the 54 patients (mean ± standard deviation [SD] age 66.9 ± 9.8; 53.7% male), 67 (62.0%), 30 (27.8%), and 11 (10.2%) eyes had primary open angle glaucoma, angle closure glaucoma, and no glaucoma respectively. Eighteen (33.3%), 11 (20.4%), 8 (14.8%), 12 (22.2%), and 5 (9.3%) patients had no, mild, moderate, severe, or advanced/end-stage glaucoma (better eye), respectively. Initially, 311 items within nine HRQoL domains were identified: Visual Symptoms, Ocular Comfort Symptoms, Activity Limitation, Driving, Lighting, Mobility, Psychosocial, Glaucoma management, and Work; however, Driving and Visual Symptoms were subsequently removed during the refinement process. During cognitive interviews, 12, 23 and 10 items were added, dropped and modified, respectively. CONCLUSION: Following a rigorous process, we developed a 221-item, 7-domain Asian glaucoma-specific IB. Once operationalised using CAT, this new instrument will enable precise, rapid, and comprehensive assessment of the HRQoL impact of glaucoma and associated treatment efficacy.

A Pooled Assessment of Ocular Surface Disease After Switching from Preserved Prostaglandins to Tafluprost Across Six Countries in Asia.

Background: Preserved prostaglandin analogs (PGAs) have been linked to ocular surface disease (OSD). While the benefits of preservative-low (PL) or -free (PF) Tafluprost (Santen Inc., Japan) were reported in real-world studies in Western countries, this is the first study in Asia to assess the effectiveness and safety of switching from preserved PGA to PL or PF-Tafluprost. Methods: We conducted a meta-analysis on studies that included adults (>18 years of age) with a Corneal Fluorescein Staining Score (CFS) >1. These individuals had switched to PL or PF-tafluprost after using a preserved PGA therapy for at least 3 months for glaucoma and were identified from Santen's tafluprost study database. A total of six studies from South Korea, Philippines, Malaysia, Singapore, Thailand, Taiwan were pooled for analysis. Results: An intraocular pressure (IOP) reduction of 5.9% (0.91 mmHg) was seen in 265 patients. However, this result was not statistically significant (95% CI: -3.64, 1.81; Figure 1). Among 132 patients, a 47.9% reduction in the CFS (95% CI: -3.65, -1.91) was seen. Tear film break-up (n=183) significantly increased by 1.06 seconds (95% CI: 0.65, 1.47). In 88 patients, the bulbar conjunctiva score decreased by -0.46 (95% CI: -0.81, -0.10) and palpebral conjunctiva score decreased by -0.42 (95% CI: -0.67-0.17). One or more new adverse reactions were reported in 3% of the individuals after switching. Conclusion: Tafluprost IOP reduction is comparable to other PGAs, with significant improvements in the ocular surface and minimal adverse reactions which were already previously reported.

Valproic acid modulates collagen architecture in the postoperative conjunctival scar.

Valproic acid (VPA), widely used for the treatment of neurological disorders, has anti-fibrotic activity by reducing collagen production in the postoperative conjunctiva. In this study, we investigated the capacity of VPA to modulate the postoperative collagen architecture. Histochemical examination revealed that VPA treatment was associated with the formation of thinner collagen fibers in the postoperative days 7 and 14 scars. At the micrometer scale, measurements by quantitative multiphoton microscopy indicated that VPA reduced mean collagen fiber thickness by 1.25-fold. At the nanometer scale, collagen fibril thickness and diameter measured by transmission electron microscopy were decreased by 1.08- and 1.20-fold, respectively. Moreover, delicate filamentous structures in random aggregates or closely associated with collagen fibrils were frequently observed in VPA-treated tissue. At the molecular level, VPA reduced Col1a1 but induced Matn2, Matn3, and Matn4 in the postoperative day 7 conjunctival tissue. Elevation of matrilin protein expression induced by VPA was sustained till at least postoperative day 14. In primary conjunctival fibroblasts, Matn2 expression was resistant to both VPA and TGF-ß2, Matn3 was sensitive to both VPA and TGF-ß2 individually and synergistically, while Matn4 was modulable by VPA but not TGF-ß2. MATN2, MATN3, and MATN4 localized in close association with COL1A1 in the postoperative conjunctiva. These data indicate that VPA has the capacity to reduce collagen fiber thickness and potentially collagen assembly, in association with matrilin upregulation. These properties suggest potential VPA application for the prevention of fibrotic progression in the postoperative conjunctiva. KEY MESSAGES: VPA reduces collagen fiber and fibril thickness in the postoperative scar. VPA disrupts collagen fiber assembly in conjunctival wound healing. VPA induces MATN2, MATN3, and MATN4 in the postoperative scar.

Effects of Valproic Acid and Mitomycin C Combination Therapy in a Rabbit Model of Minimally Invasive Glaucoma Surgery.

Purpose: This study aimed to compare the effectiveness of combination therapy consisting of low-dose mitomycin C (MMC) and valproic acid (VPA) against high-dose MMC for improving the scar phenotype in minimally invasive glaucoma surgery (MIGS). Methods: A rabbit model of MIGS incorporating the PreserFlo MicroShunt was treated with high (0.4 mg/mL) or low (0.1 mg/mL) doses of MMC or with combination therapy consisting of low-dose (0.1 mg/mL) MMC and VPA. Operated eyes were examined by live ocular imaging, histochemical evaluation, multiphoton quantitation of collagen characteristics, and molecular analyses. Results: Although high-dose MMC obliterated the vasculature, combination therapy vastly improved the postoperative tissue morphology by maintaining the vasculature without increased vascularization. Combination therapy also altered collagen morphology and reduced encapsulation of the MicroShunt distal end, which remained at risk with MMC treatment alone. Multiphoton quantitation indicated that the combination therapy significantly reduced collagen density and fiber dimensions compared with monotherapy. At the molecular level, combination therapy significantly reduced Vegfa, Vegfc, and Vegfd expression and inhibited Col1a1 upregulation from baseline levels, all of which low-dose MMC alone was unable to achieve. Notably, COL1A1 protein levels appeared more consistently suppressed by combination therapy compared with high-dose MMC alone. Conclusions: Compared with high-dose MMC, combination therapy was less toxic by sparing the vasculature and potentially more effective in reducing scarring via the regulation of collagen content and organization. Translational Relevance: VPA may be combined with low-dose MMC to replace high-dose MMC to deliver safe and effective anti-scarring outcomes.

Effect of peripheral iridectomy on VEGF-A and TGF-ß levels in rabbit aqueous humour.

BACKGROUND: Peripheral iridectomy (PI), routinely performed during glaucoma filtration surgery, may contribute to scarring. This study aims to determine whether PI alters the concentrations of VEGF-A and TGF-ß isoforms in the rabbit aqueous humour. METHODS: Anterior chamber paracentesis (ACP) was performed in both eyes of six New Zealand white rabbits, with additional surgical PI performed in the right eyes. Eyes were examined on postoperative days (PODs) 1, 7, 30 and 60 by means of the tonopen, slit-lamp biomicroscopy, and bead-based cytokine assays for TGF-ß and VEGF-A concentrations in the aqueous humor. RESULTS: ACP caused a significant reduction in intraocular pressure (IOP) from mean preoperative 11.47 ± 1.01 mmHg to 5.67 ± 1.63 mmHg on POD 1 while PI did not cause further IOP reduction. Limbal conjunctival vasculature appeared slightly increased on POD 1 in both ACP and PI eyes with PI also causing mild bleeding from damaged iris vessels. Two PI eyes developed fibrinous anterior chamber reaction and/ or peripheral anterior synechiae. Aqueous VEGF-A levels were not significantly different between eyes treated with ACP and PI. Aqueous TGF-ß concentrations distributed in the ratio of 4:800:1 for TGF-ß1:TGF-ß2:TGF-ß3 respectively. While aqueous TGF-ß2 was not significantly induced by either procedure at any time point, TGF-ß1 and TGF-ß3 were significantly induced above baseline levels by PI on POD 1. CONCLUSION: PI increases the risk of inflammation. The combined induction of aqueous TGF-ß1 and TGF-ß3 by PI in glaucoma surgery may impact surgery success in glaucoma subtypes sensitive to these isoforms.

Effect of valproic acid on functional bleb morphology in a rabbit model of minimally invasive surgery.

PURPOSE: To determine the effect of valproic acid (VPA) on bleb morphology and scar characteristics in a rabbit model of minimally invasive glaucoma surgery (MIGS). METHODS: Nine New Zealand white rabbits were subjected to MIGS with intraoperative implantation of the PreserFlo MicroShunt. Rabbits were then administered with subconjunctival injections of phosphate buffered saline (PBS) (n=4) or with VPA (n=5). Bleb morphology was examined by slit-lamp biomicroscopy and in vivo confocal microscopy. Postoperative day 28 tissues were examined by immunohistochemical evaluation and label-free multiphoton microscopy to visualise the collagen matrix, by terminal deoxynucleotidyl transferase dUTP nick-end labelling assay and immunofluorescent labelling for Ki67 expression to detect apoptosis and cell growth, and by real-time quantitative PCR to measure Col1a1, Fn, and Smad6 transcript expression. RESULTS: VPA-treated blebs were detectable on day 28, while the PBS-treated blebs were not detectable by day 14. VPA-treated blebs were diffuse, extended posteriorly with near normal conjunctival vascularity and featured a combination of reticular/blurred stromal pattern with evidence of relatively large stromal cysts. Instead of the deposition of thick, disorganised collagen fibres characteristic of the PBS bleb, the VPA bleb contained conspicuously thinner collagen fibres which were associated with similarly thinner fibronectin fibres. In corroboration, Col1a1 and Fn mRNA expression was reduced in the VPA blebs, while increased Smad6 expression implicated the disruption of the transforming growth factor beta pathway. Apoptosis and cell growth profiles appeared similar with both treatments. CONCLUSIONS: The results support the application of VPA to enhance bleb morphology associated with good bleb function in MIGS with no apparent cytotoxicity.

Aqueous outflow channels and its lymphatic association: A review.

The human eye has a unique immune architecture and behavior. While the conjunctiva is known to have a well-defined lymphatic drainage system, the cornea, sclera, and uveal tissues were historically considered "alymphatic" and thought to be immune privileged. The very fact that the aqueous outflow channels carry a clear fluid (aqueous humor) along the outflow pathway makes it hard to ignore its lymphatic-like characteristics. The development of novel lymphatic lineage markers and expression of these markers in aqueous outflow channels and improved imaging capabilities has sparked a renewed interest in the study of ocular lymphatics. Ophthalmic lymphatic research has had a directional shift over the last decade, offering an exciting new physiological platform that needs further in-depth understanding. The evidence of a presence of distinct lymphatic channels in the human ciliary body is gaining significant traction. The uveolymphatic pathway is an alternative new route for aqueous outflow and adds a new dimension to pathophysiology and management of glaucoma. Developing novel animal models, markers, and non-invasive imaging tools to delineate the core anatomical structure and physiological functions may help pave some crucial pathways to understand disease pathophysiology and help develop novel targeted therapeutic approaches for glaucoma.

Liposomal drug delivery system for anti-inflammatory treatment after cataract surgery: a phase I/II clinical trial.

Liposomes as a drug delivery system may overcome the problems associated with non-compliance to eyedrops and inadequate control of inflammation after cataract surgery. We evaluated the safety and efficacy of a single subconjunctival injection of liposomal prednisolone phosphate (LPP) for the treatment of post-cataract surgery inflammation. This is a phase I/II, open-label non-comparative interventional trial of patients undergoing cataract surgery. All patients received a single injection of subconjunctival LPP intraoperatively. The primary outcome measure was the proportion of eyes with an anterior chamber cell count of 0 at postoperative month 1. Ocular and non-ocular adverse events, including elevated intraocular pressure, rebound iritis and pseudophakic macular edema were monitored. Five patients were enrolled in this study. The mean age was 66.6 ± 6.2 and 4 (80%) were male. The proportion of patients with AC cell grading of 0 was 0%, 80%, 80%, and 100% at day 1, week 1, month 1, and month 2 after cataract surgery, respectively. Mean laser flare photometry readings were significantly elevated at week 1 after cataract surgery (48.8 ± 18.9, p = 0.03) compared with baseline, decreasing to 25.8 ± 9.2 (p = 0.04) at month 1 and returned to baseline by month 2 (10.9 ± 5.1, p = 1.0). No ocular or non-ocular adverse events were observed. Liposomal prednisolone phosphate, administered as a single subconjunctival injection intraoperatively, can be a safe and effective treatment for post-cataract surgery inflammation. The delivery of steroids with a liposomal drug delivery system could potentially replace eyedrops as anti-inflammatory therapy following cataract surgery.

Full circumferential morphological analysis of Schlemm's canal in human eyes using megahertz swept source OCT.

We performed full circumferential imaging of the Schlemm's canal (SC) of two human eyes using a Fourier domain mode-lock laser (FDML) based 1.66-MHz SS-OCT prototype at 1060 nm. Eight volumes with overlapping margins were acquired around the limbal area with customized raster scanning patterns designed to fully cover the SC while minimizing motion artifacts. The SC was segmented from the volumes using a semi-automated active contour segmentation algorithm, whose mean dice similarity coefficient was 0.76 compared to the manual segmentation results. We also reconstructed three-dimensional (3D) renderings of the 360° SC by stitching the segmented SCs from the volumetric datasets. Quantitative metrics of the full circumferential SC were provided, including the mean and standard deviation (SD) of the cross-sectional area (CSA), the maximum CSA, the minimum and maximum SC opening width, and the number of collector channels (CC) stemming from the SC.

Outcomes of an Asynchronous Virtual Glaucoma Clinic in Monitoring Patients at Low Risk of Glaucoma Progression in Singapore.

PURPOSE: To assess the implementation outcomes of a new asynchronous virtual clinic, the Glaucoma Observation Clinic (GLOC), at the Singapore National Eye Center, in monitoring patients at low risk for glaucoma progression. METHODS: Patients with low risk of glaucoma progression were followed up at GLOC. Visual acuity, intraocular pressure, and visual field testing or optic nerve head imaging were assessed by nurses and technicians, with virtual review of data by an ophthalmologist separately. The implementation outcomes were defined as patient satisfaction, assessed by a nurse-administered questionnaire; the rate of referrals back to the glaucoma outpatient department; the patients' journey time (minutes); the time taken for the specialist review (minutes), and the per capita manpower cost compared with current glaucoma outpatient model. RESULTS: A total of 377 patients were included, with the majority being glaucoma disc suspects (n = 250, 66.4%) and primary angle closure suspects (n = 54, 14.3%). Most patients (more than 90%) reported being satisfied, and only 7.7% (n = 29) were referred back to the specialist outpatient glaucoma clinic due to possible glaucoma progression. Compared with the glaucoma outpatient clinic, the average journey time in GLOC was 50% less (59.3 mins vs 132 mins), the average time for a specialist review was 3 times faster (5.8 mins vs 19.5 mins), and the per capita manpower cost of GLOC was halved ($20.07 vs $39.78). CONCLUSIONS: GLOC is a time-efficient, cost-saving, and sustainable model of care for managing patients with low risk of glaucoma progression. It was well received by patients and freed up the conventional clinic to treat patients with complex needs.

Association of peripheral anterior synechiae with anterior segment parameters in eyes with primary angle closure glaucoma.

To investigate the association of peripheral anterior synechiae (PAS) with intraocular pressure (IOP) and anterior-segment parameters in subjects with primary angle-closure glaucoma (PACG). A total of 267 subjects with PACG were recruited and underwent gonioscopy and anterior-segment optical coherence tomography (ASOCT). Customized software was used to measure ASOCT parameters, including angle opening distance (AOD750) and trabecular-iris-space-area (TISA750) at 750 µm from the scleral spur, anterior chamber depth, width, area and volume (ACD, ACW, ACA, ACV), iris thickness (IT750), iris area (IAREA), and lens vault (LV). Presenting IOP was defined as the first IOP reading before the initiation of IOP-lowering treatment. The mean age of the 267 subjects was 67.0 ± 8.9 years, 140 (52.4%) were male, and 246 (92.1%) were of Chinese ethnicity. PAS was present in 122 (45.7%) subjects, and was most frequently found in the superior quadrant (79.5%). Subjects with PAS had greater presenting IOP (28.7 ± 12.9 vs 22.4 ± 9.7 mmHg, p < 0.001), narrower AOD750 (p < 0.001), smaller TISA750 (p < 0.001), ACD (p = 0.04), ACA (p = 0.02), ACV (p = 0.01) and larger LV (p = 0.01) compared to PACG eyes without PAS. No significant differences were noted for iris parameters. A multivariate logistic regression analysis showed that higher presenting IOP (ß = 0.20, p < 0.001), worse visual field mean deviation (ß = - 0.20, p = 0.01) and narrower AOD750 (ß = - 0.25, p = 0.03) were the only parameters that significantly correlated with the extent of PAS in clock hours. Almost one-half of the subjects with PACG demonstrated PAS; these eyes were associated with higher presenting IOP, smaller anterior segment dimensions and more severe disease.

Altered Iris Aquaporin Expression and Aqueous Humor Osmolality in Glaucoma.

Purpose: Aquaporins (AQPs) facilitate transmembrane osmotic water transport and may play a role in iris fluid conductivity, which is implicated in the pathophysiology of glaucoma. In this study, we compared the iris expression of AQPs and aqueous osmolality between primary angle closure glaucoma (PACG), primary open-angle glaucoma (POAG), and nonglaucoma eyes. Methods: AQP1-5 transcripts from a cohort of 36 PACG, 34 POAG and 26 nonglaucoma irises were measured by quantitative real-time PCR. Osmolality of aqueous humor from another cohort of 49 PACG, 50 POAG, and 50 nonglaucoma eyes were measured using an osmometer. The localization of AQP1 in both glaucoma and nonglaucoma irises was determined by immunofluorescent analysis. Results: Of the five AQP genes evaluated, AQP1 and AQP2 transcripts were significantly upregulated in both PACG (3.48- and 8.07-fold, respectively) and POAG (3.12- and 11.58-fold, respectively) irises relative to nonglaucoma counterparts. The aqueous osmolalities of PACG (303.68 mmol/kg) and POAG (300.79 mmol/kg) eyes were significantly lower compared to nonglaucoma eyes (312.6 mmol/kg). There was no significant difference in expression of AQP transcripts or aqueous osmolality between PACG and POAG eyes. Conclusions: PACG and POAG eyes featured significant increase in AQP1 and AQP2 expression in the iris and reduced aqueous osmolality compared to nonglaucoma eyes. These findings suggest that the iris may be involved in altered aqueous humor dynamics in glaucoma pathophysiology. Because PACG did not differ from POAG in both properties studied, it is likely that they are common to glaucoma disease in general.

Positive-charge tuned gelatin hydrogel-siSPARC injectable for siRNA anti-scarring therapy in post glaucoma filtration surgery.

Small interfering RNA (siRNA) therapy is a promising epigenetic silencing strategy. However, its widespread adoption has been severely impeded by its ineffective delivery into the cellular environment. Here, a biocompatible injectable gelatin-based hydrogel with positive-charge tuned surface charge is presented as an effective platform for siRNA protection and delivery. We demonstrate a two-step synthesis of a gelatin-tyramine (Gtn-Tyr) hydrogel with simultaneous charge tunability and crosslinking ability. We discuss how different physiochemical properties of the hydrogel interact with siSPARC (siRNA for secreted protein, acidic and rich in cysteine), and study the positive-charge tuned gelatin hydrogel as an effective delivery platform for siSPARC in anti-fibrotic treatment. Through in vitro studies using mouse tenon fibroblasts, the positive-charge tuned Gtn-Tyr hydrogel shows sustained siSPARC cellular internalization and effective SPARC silencing with excellent biocompatibility. Similarly, the same hydrogel platform delivering siSPARC in an in vivo assessment employing a rabbit model shows an effective reduction in subconjunctival scarring in post glaucoma filtration surgery, and is non-cytotoxic compared to a commonly used anti-scarring agent, mitomycin-C. Overall, the current siRNA delivery strategy involving the positive-charge tuned gelatin hydrogel shows effective delivery of gene silencing siSPARC for anti-fibrotic treatment. The current charge tunable hydrogel delivery system is simple to fabricate and highly scalable. We believe this delivery platform has strong translational potential for effective siRNA delivery and epigenetic silencing therapy.

RelB regulates basal and proinflammatory induction of conjunctival CCL2.

Purpose: This study investigated the involvement of NF-kB in regulating postoperative conjunctival inflammation.Methods: Experimental surgery was performed as described for the mouse model of conjunctival scarring. Expression of NF-κB in postoperative conjunctival tissues or conjunctival fibroblasts were assessed by real-time PCR, immunoblotting and immunofluorescence analyses. Downregulation of RelB was achieved using small interfering RNA. Cellular cytokine secretion was determined using multiplex cytokine assay.Results: RelB was the most highly induced member of the NF-kB family on day 2 post-surgery. Elevated RelB may be found associated with vimentin-positive cells and fibroblasts in vivo and in vitro. In conjunctival fibroblasts, RelB may be induced by TNF-α but not TGF-ß2 while its silencing caused selective induction of CCL2 secretion by both basal and TNF-α-stimulated fibroblasts.Conclusions: High RelB induction in the inflammatory phase and the selective modulation of CCL2 suggest a specific anti-inflammatory role for RelB in the postoperative conjunctiva.