Reduced Aqueous Humor Outflow Pathway Arborization in Childhood Glaucoma Eyes.

Purpose: To compare aqueous humor outflow (AHO) pathway patterns between eyes of childhood glaucoma patients and non-glaucomatous patients receiving cataract surgery. Methods: Aqueous angiography was performed in childhood glaucoma eyes (n = 5) receiving glaucoma surgery and in pediatric (n = 1) and healthy adult (n = 5) eyes receiving cataract surgery. Indocyanine green (0.4%) was introduced into the anterior chamber, and AHO was imaged using an angiographic camera (SPECTRALIS HRA+OCT with Flex Module). Images were acquired and analyzed (ImageJ with Analyze Skeleton 2D/3D plugin) from the nasal sides of the eyes, the usual site of glaucoma angle procedures. Image analysis endpoints included AHO vessel length, maximum vessel length, number of branches, number of branch junctions, and vessel density. Results: Qualitatively, childhood glaucoma eyes demonstrated lesser AHO pathway arborization compared to pediatric and adult eyes without glaucoma. Quantitatively, childhood glaucoma and healthy adult cataract eyes showed similar AHO pathway average branch lengths and maximum branch lengths (P = 0.49-0.99). However, childhood glaucoma eyes demonstrated fewer branches (childhood glaucoma, 198.2 ± 35.3; adult cataract, 506 ± 59.5; P = 0.002), fewer branch junctions (childhood glaucoma, 74.6 ± 13.9; adult cataract, 202 ± 41.2; P = 0.019), and lower vessel densities (childhood glaucoma, 8% ± 1.4%; adult cataract, 17% ± 2.5%; P = 0.01). Conclusions: Childhood glaucoma patients demonstrated fewer distal AHO pathways and lesser AHO pathway arborization. These anatomical alternations may result in a new source of trabecular meshwork-independent AHO resistance in this disease cohort. Translational Relevance: Elevated distal outflow pathway resistance due to decreased AHO pathway arborization may explain some cases of failed trabecular bypass surgery in childhood glaucoma.

Bleb vessel density as a predictive factor for surgical revisions after Preserflo Microshunt implantation.

PURPOSE: Bleb failure is a common complication after glaucoma filtration surgery. Different bleb classification schemes incorporating filtration bleb vascularization have been proposed, but the reported correlation with intraocular pressure (IOP) has been variable, possibly because of subjective vascularization grading. The purpose of the present study was to evaluate bleb vascularization after Preserflo Microshunt (PM) implantation using anterior segment OCT-angiography (AS-OCTA) as a biomarker for bleb failure. METHODS: Twenty-three eyes of twenty-three patients underwent PM implantation. Up to 12 months after surgery PM scleral passage-centred AS-OCTA measurements (PLEX Elite 9000) for bleb-vessel density (BVD) determination were performed and IOP as well as necessity for surgical revisions (needling and open revision) were documented. After multi-step image analysis (region of interest definition, artefact removal, binarization, BVD calculation), the predictive value of early postoperative BVD for surgical revisions was assessed using logistic regression modelling. RESULTS: Baseline IOP (23.57 ± 7.75 mmHg) decreased significantly to 8.30 ± 2.12, 9.17 ± 2.33 and 11.70 ± 4.40 mmHg after 1, 2 and 4 week(s), and 13.48 ± 5.83, 11.87 ± 4.49, 12.30 ± 6.65, 11.87 ± 3.11 and 13.05 ± 4.12 mmHg after 2, 3, 6, 9 and 12 month(s), respectively (p < 0.001). Nine patients (39%) needed surgical revisions after a median time of 2 months. Bleb vessel densities at 2 and 4 weeks were significantly associated with future surgical revisions upon logistic regression analysis (2 W/4 W likelihood-ratio test p-value: 0.0244/0.0098; 2 W/4 W area under the receiver operating characteristics curve: 0.796/0.909). CONCLUSION: Filtration bleb vessel density can be determined using AS-OCTA in the early postoperative period and is predictive for bleb failure after PM implantation.

Lack of Correlation Between Segmental Trabecular Meshwork Pigmentation and Angiographically Determined Outflow in Ex-Vivo Human Eyes.

PRECIS: Trabecular meshwork pigmentation is not correlated with angiographically determined aqueous humor outflow in an ex-vivo perfusion model using human eyes. PURPOSE: To evaluate whether segmental trabecular meshwork (TM) pigmentation is correlated to segmental aqueous humor outflow (AHO) in human eyes. METHODS: Post-mortem human eyes were acquired, and anterior segments were dissected. TM pigmentation was photographed 360-degrees around the eye. The anterior segments were then mounted onto a perfusion apparatus and perfused with DPBS until a stabile baseline outflow facility was achieved. Aqueous angiography (AHO angiography) was performed using fluorescein (2%), and segmental AHO was documented around the limbus using an angiographic camera (Spectralis HRA+OCT). Circumferential and nasal TM pigmentation were compared to respective angiographic outflow imaging using a Pearson's correlation analysis. RESULTS: Segmental TM pigment distribution and segmental AHO were seen. TM pigment was statistically greatest in the inferior quadrant. AHO angiographic outflow was numerically greatest in the nasal quadrant, but this was not statistically significant. No statistically significant correlation was observed (r=-0.083, P=0.06) between segmental TM pigmentation and segmental AHO angiographic signal. Analyzing just the nasal quadrant, a significant weak negative correlation was found (r=-0.296, P=0.001). DISCUSSION: Segmental TM pigmentation circumferentially around the eye is not a good proxy for segmental AHO circumferentially around the eye and should not be used to guide trabecular minimally invasive glaucoma surgeries.

Greater Outflow Facility Increase After Targeted Trabecular Bypass in Angiographically Determined Low-low Regions.

PURPOSE: To investigate the impact of trabecular bypass surgery targeted to angiographically determined high- vs. low-aqueous humor outflow areas on outflow facility (C) and intraocular pressure (IOP). DESIGN: Ex vivo comparative study. SUBJECTS: Postmortem ex vivo porcine and human eyes. METHODS: Porcine (n = 14) and human (n = 13) whole globes were acquired. In both species, anterior segments were dissected, mounted onto a perfusion chamber, and perfused using Dulbecco's phosphate buffered solution containing glucose in a constant flow paradigm to achieve a stable baseline. Fluorescein was perfused into the anterior chamber and used to identify baseline segmental high- and low-flow regions of the conventional outflow pathways. The anterior segments were divided into 2 groups, and a 5 mm needle goniotomy was performed in either a high- or low-flow area. Subsequently, C and IOP were quantitatively reassessed and compared between surgery in baseline "high-flow" and "low-flow" region eyes followed by indocyanine green angiography. MAIN OUTCOME MEASURES: Outflow facility. RESULTS: In all eyes, high- and low-flow segments could be identified. Performing a 5-mm goniotomy increased outflow facility to a variable extent depending on baseline flow status. In the porcine high-flow group, C increased from 0.31 ± 0.09 to 0.39 ± 0.09 µL/mmHg/min (P = 0.12). In the porcine low-flow group, C increased from 0.29 ± 0.03 to 0.56 ± 0.10 µL/mmHg/min (P < 0.001). In the human high-flow group, C increased from 0.38 ± 0.20 to 0.41 ± 0.20 µL/mmHg/min (P = 0.02). In the human low-flow group, C increased from 0.25 ± 0.11 to 0.32 ± 0.11 µL/mmHg/min (<0.001). There was statistically significant greater increase in C for eyes where surgery was targeted to baseline low-flow regions in both porcine (0.07 ± 0.09 vs. 0.27 ± 0.13, P = 0.007 µL/mmHg/min, high vs low flow) and human eyes (0.03 ± 0.03 vs. 0.07 ± 0.02, P = 0.03 µL/mmHg/min, high vs. low flow). CONCLUSIONS: Targeting surgery to low-flow areas of the trabecular meshwork yields higher overall facility increase and IOP reduction compared to surgery in high-flow areas. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Differences in Outflow Facility Between Angiographically Identified High- Versus Low-Flow Regions of the Conventional Outflow Pathways in Porcine Eyes.

Purpose: To investigate differences in outflow facility between angiographically determined high- and low-flow segments of the conventional outflow pathway in porcine eyes. Methods: Porcine anterior segments (n = 14) were mounted in a perfusion chamber and perfused using Dulbecco's phosphate buffered solution with glucose. Fluorescein angiography was performed to determine high- and low-flow regions of the conventional outflow pathways. The trabecular meshwork (TM) was occluded using cyanoacrylate glue, except for residual 5-mm TM areas that were either high or low flow at baseline, designating these eyes as "residual high-flow" or "residual low-flow" eyes. Subsequently, outflow was quantitatively reassessed and compared between residual high-flow and residual low-flow eyes followed by indocyanine green angiography. Results: Fluorescein aqueous angiography demonstrated high-flow and low-flow regions. Baseline outflow facilities were 0.320 ± 0.08 and 0.328 ± 0.10 µL/min/mmHg (P = 0.676) in residual high-flow and residual low-flow eyes before TM occlusion, respectively. After partial trabecular meshwork occlusion, outflow facility decreased to 0.209 ± 0.07 µL/min/mmHg (-32.66% ± 19.53%) and 0.114 ± 0.08 µL/min/mmHg (-66.57% ± 23.08%) in residual high- and low-flow eyes (P = 0.035), respectively. There was a significant difference in the resulting IOP increase (P = 0.034). Conclusions: Angiographically determined high- and low-flow regions in the conventional outflow pathways differ in their segmental outflow facility; thus, there is an uneven distribution of local outflow facility across different parts of the TM.

Urocortin-positive nerve fibres and cells are present in the human choroid.

BACKGROUND: Choroidal vascular regulation is mediated by the autonomic nervous system in order to gain proper blood flow control. While the mechanisms behind this control are unknown, neuroregulatory peptides are involved in this process. To better understand choroidal function, we investigate the presence of urocortin-1 (UCN), a neuroregulatory peptide with vascular effects, in the human choroid and its possible intrinsic and extrinsic origin. METHODS: Human choroid and eye-related cranial ganglia (superior cervical ganglion- SCG, ciliary ganglion-CIL, pterygopalatine ganglion-PPG, trigeminal ganglion-TRI) were prepared for immunohistochemistry against UCN, protein-gene product 9.5 (PGP9.5), substance P (SP), tyrosine hydroxylase (TH) and vesicular acetylcholine transporter (VAChT). For documentation, confocal laser scanning microscopy was used. RESULTS: In choroidal stroma, UCN-immunoreactivity was present in nerve fibres, small cells and intrinsic choroidal neurons (ICN). Some UCN+ nerve fibres colocalised for VAChT, while others were VAChT. A similar situation was found with SP: some UCN+ nerve fibres showed colocalisation for SP, while others lacked SP. Colocalisation for UCN and TH was not observed. In eye-related cranial ganglia, only few cells in the SCG, PPG and TRI were UCN+, while many cells of the CIL displayed weak UCN immunoreactivity. CONCLUSION: UCN is part of the choroidal innervation. UCN+/VAChT+ fibres could derive from the few cells of the PPG or cells of the CIL, if these indeed supply the choroid. UCN+/SP+ fibres might originate from ICN, or the few UCN+ cells detected in the TRI. Further studies are necessary to establish UCN function in the choroid and its implication for choroidal autonomic control.

Subconjunctival Lymphatics Respond to VEGFC and Anti-Metabolites in Rabbit and Mouse Eyes.

Purpose: To characterize and pharmacologically influence subconjunctival lymphatics in rabbit and mouse eyes. Methods: Rabbits received subconjunctival injections of trypan blue or fixable fluorescent dextrans. Bleb-related outflow pathways were quantified. Immunofluorescence for vessel-specific markers (lymphatics [podoplanin and LYVE-1] and blood vessels [CD31]) were performed in native rabbit conjunctiva and after fixable fluorescent dextran injection. Vascular endothelial cell growth factor-C (VEGFC) was injected subconjunctivally in rabbits. mRNA and protein were assessed for the above markers using RT-PCR and Western blot. Alternatively, mouse studies used Prox1-tdTomato transgenic reporter mice. Subconjunctival injection conditions included: no injection, balanced salt solution (BSS), VEGFC, 5-fluorouracil (5FU) and two concentrations of mitomycin-C (MMC). Two mouse injection protocols (short and long) with different follow-up times and number of injections were performed. Mouse eyes were enucleated, flat mounts created, and subconjunctival branching and length assessed. Results: Rabbit eyes demonstrated clear bleb-related subconjunctival outflow pathways that were distinct from blood vessels and were without nasal/temporal predilection. Immunofluorescence against vessel-specific markers showed lymphatics and blood vessels in rabbit conjunctiva, and these lymphatics overlapped with bleb-related subconjunctival outflow pathways. Subconjunctival VEGFC increased lymphatic (P = 0.004-0.04) but not blood vessel (P = 0.77-0.84) mRNA or protein in rabbits. Prox1-tdTomato transgenic reporter mice demonstrated natively fluorescent lymphatics. Subconjunctival VEGFC increased murine lymphatic branching and length (P ≤ 0.001-0.004) while antimetabolites (P ≤ 0.001-0.043) did the opposite for the long protocol. Discussion: Subconjunctival lymphatics are pharmacologically responsive to both VEGFC and antimetabolites in two animal models studied using different methodologies. These results may be important for bleb-forming glaucoma surgeries or ocular drug delivery.

Aqueous Angiography-guided Minimally Invasive Glaucoma Surgery.

How to cite this article: Dada T, Verma S, Bukke AN, et al. Aqueous Angiography-guided Minimally Invasive Glaucoma Surgery. J Curr Glaucoma Pract 2022;16(1):1-3.

Case report: atypical, unilateral optic nerve infiltration as the first sign of acute lymphoblastic leukemia (ALL) relapse.

BACKGROUND: We describe a case of an atypical presentation of leukemic optic nerve infiltration. CASE PRESENTATION: A patient with acute lymphoblastic leukemia (ALL) in remission suffered from sudden right eye vision loss. At the time of presentation, the affected eye presented with an afferent pupillary defect, while the fundus examination was normal. A complete work up of the patient revealed no signs of ALL relapse, but MR imaging of the optic nerve showed contrast agent uptake consistent with optic nerve infiltration. The patient developed a fulminant ALL relapse and died shortly after. Histology of the optic nerve showed a leukemic infiltration with CD10 positive cells. CONCLUSIONS: This is the first report of an ALL relapse in the optic nerve without intraocular signs. Patients' medical history should therefore be taken into consideration in patients with unclear vision loss.

Bleb-related Porcine Lymphatic Outflow is Greater from Subconjunctival compared to Subtenon Blebs.

Aim: Understanding the mechanism of fluid outflow by comparing the subconjunctival and subtenon spaces can lead to improved ocular therapeutics. The purpose of the current study is to evaluate subconjunctival vs subtenon lymphatic outflow by creating tracer-filled blebs in each location. Methods: Porcine (n = 20) eyes received subconjunctival or subtenon injection(s) of fixable and fluorescent dextrans. Blebs were angiographically imaged using a Heidelberg Spectralis ([Heidelberg Retina Angiograph] HRA + OCT; Heidelberg Engineering) and bleb-related lymphatic outflow pathways were counted. Optical coherence tomography (OCT) imaging of these pathways was used to assess structural lumens and the presence of valve-like structures. Furthermore, a comparison between tracer injection locations (superior/inferior/temporal/nasal) was made. Histologic analyses for subconjunctival and subtenon outflow pathways were performed, to confirm tracer co-localization with molecular lymphatic markers. Results: Subconjunctival blebs demonstrated a greater number of lymphatic outflow pathways compared to subtenon blebs in every quadrant [superior: 6.10 ± 1.18 (subconjunctival) vs 0.50 ± 0.27 (subtenon); temporal: 2.30 ± 0.40 vs 0.10 ± 0.10; nasal: 5.30 ± 0.60 vs 0.30 ± 0.21; inferior: 6.00 ±1.29 vs 0.1 ± 0.1; all comparisons p < 0.001]. For subconjunctival blebs, the temporal quadrant showed fewer lymphatic outflow pathways compared to the nasal side (p = 0.005). Discussion: Subconjunctival blebs accessed greater lymphatic outflow compared to subtenon blebs. Furthermore, regional differences existed, with fewer lymphatic vessels temporal than at the other locations. Clinical significance: Aqueous humor drainage after glaucoma surgery is incompletely understood. The present manuscript adds to our understanding of how lymphatics might influence filtration bleb function. How to cite this article: Lee JY, Strohmaier CA, Akiyama G, et al. Bleb-related Porcine Lymphatic Outflow Is Greater from Subconjunctival compared to Subtenon Blebs. J Curr Glaucoma Pract 2022;16(3):144-151.

Inhibition of the cysteinyl leukotriene pathways increases survival of RGCs and reduces microglial activation in ocular hypertension.

Glaucoma is the second leading cause of blindness worldwide. This multifactorial, neurodegenerative group of diseases is characterized by the progressive loss of retinal ganglion cells (RGCs) and their axons, leading to irreversible visual impairment and blindness. There is a huge unmet and urging need for the development of new and translatable strategies and treatment options to prevent this progressive loss of RGC. Accumulating evidence points towards a critical role of neuroinflammation, in particular microglial cells, in the pathogenesis of glaucoma. Leukotrienes are mediators of neuroinflammation and are involved in many neurodegenerative diseases. Therefore, we tested the leukotriene receptors CysLT1R/GPR17-selective antagonist Montelukast (MTK) for its efficacy to modulate the reactive state of microglia in order to ameliorate RGCs loss in experimental glaucoma. Ocular hypertension (OHT) was induced unilaterally by injection of 8 µm magnetic microbead (MB) into the anterior chamber of female Brown Norway rats. The contralateral, untreated eye served as control. Successful induction of OHT was verified by daily IOP measurement using a TonoLab rebound tonometer. Simultaneously to OHT induction, one group received daily MTK treatment and the control group vehicle solution by oral gavage. Animals were sacrificed 13-15 days after MB injection. Retina and optic nerves (ON) of OHT and contralateral eyes were analyzed by immunofluorescence with specific markers for RGCs (Brn3a), microglial cells/macrophages (Iba1 and CD68), and cysteinyl leukotriene pathway receptors (CysLT1R and GPR17). Protein labeling was documented by confocal microscopy and analyzed with ImageJ plugins. Further, mRNA expression of genes of the inflammatory and leukotriene pathway was analyzed in retinal tissue. MTK treatment resulted in a short-term IOP reduction at day 2, which dissipated by day 5 of OHT induction in MTK treated animals. Furthermore, MTK treatment resulted in a decreased activation of Iba1+ microglial cells in the retina and ON, and in a significantly increased RGC survival in OHT eyes. Within the retina, GPR17 and CysLT1R expression was demonstrated in single RCGs and in microglial cells respectively. Further, increased mRNA expression of pro-inflammatory genes was detected in OHT induced retinas. In the ON, OHT induction increased the number of GPR17+ cells, showing a trend of reduction following MTK treatment. This study shows for the first time a significantly increased RGC survival in an acute OHT model following treatment with the leukotriene receptor antagonist MTK. These results strongly suggest a neuroprotective effect of MTK and a potential new therapeutic strategy for glaucoma treatment.

Episcleral venous pressure response to brain stem stimulation: Effect of topical lidocaine.

Episcleral venous pressure (EVP) is important for steady state intraocular pressure (IOP), as it has to be overcome by aqueous humor in order to leave the eye. Recent evidence suggests a neuronal tone being present, as topical anesthesia lowered EVP. The superior salivatory nucleus in the brainstem could be identified to elicit increases in EVP during electrical stimulation. In the present study the effect of topical anesthesia on the stimulation effect was investigated. 8 Spraque Dawley rats were anesthetized, artificially ventilated with CO2 monitoring and continuous blood pressure monitoring. Intraocular pressure was measured continuously through a cannula in the vitreous body. Episcleral venous pressure was measured by direct cannulation of an episcleral vein via a custom made glass pipette connected to a servonull micropressure system. Electrical stimulation of the superior salivatory nucleus (9 µA, 200 pulses of 1 ms duration) increased EVP from 8.51 ± 1.82 mmHg to 10.97 ± 1.93 mmHg (p = 0.004). After application of topical lidocaine EVP increased from 7.42 ± 1.59 mmHg to 9.77 ± 1.65 mmHg (p = 0.007). The EVP response to stimulation before and after lidocaine application was not statistically significantly different (2.45 ± 0.5 vs 2.35 ± 0.49 mmHg, p = 0.69), while the decrease in baseline EVP was (8.51 vs. 7.42 mmHg, p = 0.045). The present data suggest that distinct neuronal mechanisms controlling the episcleral circulation of rats exist. This is in keeping with previous reports of two distinct arterio-venous anastomoses, one in the limbal circulation and one in the conjunctival/episcleral circulation.

Choroidal melanocytes: subpopulations of different origin?

BACKGROUND: The human choroid derives from the mesectoderm, except the melanocytes originating from the neuroectoderm. To date, it is unclear whether all choroidal melanocytes share the same origin or might have different origins. The purpose of this study was to screen immunohistochemically for mesenchymal elements in the adult healthy human choroid, in the malignant melanoma of the choroid, as well as in the developing human fetal choroid. METHODS: Human choroids were obtained from cornea donors and prepared as flat whole mounts for paraffin- and cryoembedding. Globes enucleated for choroidal melanoma and eyes from human fetuses between 11 and 20 weeks of gestation were also embedded in paraffin. Sections were processed for immunohistochemistry of the mesenchymal marker vimentin, the melanocyte marker Melan-A, and the macrophage marker CD68, followed by light-, fluorescence-, and confocal laser scanning-microscopy. RESULTS: The normal choroid contained 499 ± 139 vimentin, 384 ± 78 Melan-A, and 129 ± 57 CD68 immunoreactive cells/mm2. The vimentin immunopositive cell density was significantly higher than the density of Melan-A and CD68 immunopositive cells (p < 0.001, respectively). By confocal microscopy, 24 ± 8% of all choroidal melanocytes displayed vimentin immunoreactivity. In choroidal melanomas, numerous melanoma cells of the epithelioid and spindle cell type revealed immunopositivity for both vimentin and Melan-A. The intratumoral density of vimentin immunoreactive cells was 1758 ± 106 cells/mm2, significantly higher than the density of Melan-A and CD68 immunopositive cells (p < 0.001, respectively). Comparing to healthy choroidal tissue, the choroidal melanomas revealed significantly higher densities of vimentin, Melan-A, and CD68 immunoreactive cells (p < 0.001, respectively). In the developing human fetal choroid, numerous vimentin and Melan-A immunopositive cells were detected not before the 16th week of gestation, with some of them showing colocalization of vimentin and Melan-A. CONCLUSIONS: The adult healthy human choroid is endowed with a significant number of vimentin immunopositive mesenchymal structures, including a subpopulation of vimentin immunoreactive choroidal melanocytes. These vimentin immunopositive melanocytic cells are also present in choroidal melanomas as well as in the developing human fetal choroid. Therefore, different embryologic origins can be considered for choroidal melanocytes.

Vascular Aspects in Glaucoma: From Pathogenesis to Therapeutic Approaches.

Glaucomatous optic neuropathies have been regarded as diseases caused by high intraocular pressure for a long time, despite the concept of vascular glaucoma dating back to von Graefe in 1854. Since then, a tremendous amount of knowledge about the ocular vasculature has been gained; cohort studies have established new vascular risk factors for glaucoma as well as identifying protective measures acting on blood vessels. The knowledge about the physiology and pathophysiology of the choroidal, retinal, as well as ciliary and episcleral circulation has also advanced. Only recently have novel drugs based on that knowledge been approved for clinical use, with more to follow. This review provides an overview of the current vascular concepts in glaucoma, ranging from novel pathogenesis insights to promising therapeutic approaches, covering the supply of the optic nerve head as well as the aqueous humor production and drainage system.

Change in visual acuity 12 and 24 months after transscleral ab interno glaucoma gel stent implantation with adjunctive Mitomycin C.

PURPOSE: To analyze changes in best-corrected visual acuity (BCVA) after implantation of the transscleral ab interno glaucoma gel stent (XEN Gel Stent; Allergan, Dublin) in patients with open-angle glaucoma. METHODS: In a single-center, prospective, non-randomized study of 137 eyes with open-angle glaucoma which underwent implantation with XEN, 69 eyes underwent XEN implantation alone (group 1) and 68 eyes underwent XEN implantation and cataract surgery (group 2). BCVA (Bailey-Lovie chart, logMAR scale) was evaluated at baseline, postoperative day 1, weeks 1 and 2, and months 1, 3, 6, 12, and 24. Risk factors for decline in BCVA were analyzed in multivariate models. RESULTS: Baseline BCVA in group 1 was 0.21 ± 031; the group's mean BCVA did not change at any postoperative visit, although a ≥ 2-line loss of BCVA was detected in 15% (95% CI 7-29%) and 4% (95% CI 0-20%) after months 12 and 24, respectively. Baseline BCVA in group 2 was 0.33 ± 031; vision increased significantly at months 3 (0.22 ± 0.29, p = 0.015), 6 (0.20 ± 0.26, p = 0.006), 12 (0.18 ± 0.29, p = 0.001), and 24 (0.18 ± 0.29, p = 0.005). A ≥ 2-line loss of BCVA was reported in 4% (95% CI 1-15%) and 7% (95% CI 1-24%) after months 12 and 24, respectively. CONCLUSIONS: There was no deterioration of BCVA in group 1; those in group 2 had an overall significant increase in BCVA. BCVA decrease was lower than is typically reported in the literature post-trabeculectomy.

Immunohistochemical Characterization of Neurotransmitters in the Episcleral Circulation in Rats.

Purpose: Episcleral venous pressure (EVP) greatly influences steady-state IOP and recent evidence suggests a neuronal influence on EVP. Yet little is known about the innervation of the episcleral circulation and, more specifically, the neurotransmitters involved. We identify possible neurotransmitter candidates in the episcleral circulation of rats. Methods: Eight immersion-fixated rat eyes taken from four animals were cut into serial sections, followed by standard immunohistochemistry. Antibodies against choline acetyltransferase, dopamine-ß-hydroxylase, synaptophysine, PGP 9.5, VIP, neuronal nitric oxide synthase (nNOS), substance P, CGRP, and galanin were used. Additionally, colocalization experiments with smooth muscle actin and neurofilament (200 kDa) were performed. Results: In all specimens, the episcleral vessels showed immunoreactivity for smooth muscle actin and were reached by neurofilament (200 kDa)-positive structures. Furthermore, these structures colocalized with immunoreactivity for PGP 9.5, synaptophysine, choline acetyl transferase (ChAT), dopamine-ß-hydroxylase, VIP, CGRP, nNOS, substance P and galanin. Conclusions: These findings indicate that there is neuronal input to the episcleral circulation. ChAT and VIP as well as dopamine-ß-hydroxylase suggest parasympathetic and sympathetic innervation. Further studies are needed on whether the positively-stained structures are of functional significance for the regulation of the episcleral venous pressure and thereby IOP.

Effect of the outer stent position on efficacy after minimally invasive transscleral glaucoma gel stent implantation.

PURPOSE: The outer stent lumen can be located either deeper (in or under Tenon's layer) or more superficially in the conjunctival stroma after the transscleral XEN Glaucoma Gel Microstent (XEN-GGM; Allergan Plc., USA) implantation. The present study aimed to investigate the effect of the postoperative conjunctival implant position on surgical success and intraocular pressure (IOP) after XEN-GGM. METHODS: Prospective data from 66 consecutive open-angle glaucoma eyes of 54 patients were collected preoperatively and 1 and 2 weeks, and 1, 6 and 12 months postoperatively. The layer of implantation was determined in the first month postoperatively as intra- and subtenon or intraconjunctival depending on the location of the outer lumen of the stent in OCT (Visante OCT; Zeiss, Germany). Primary outcome measures were differences in relative IOP reduction at 12 months between the two groups. Further, complete and qualified surgical success, number of secondary needlings and number of IOP-lowering medications and absolute IOP were assessed. RESULTS: Relative IOP reduction was higher in intra- and subtenon group (n = 37/66, 56%) at week 1 (-54% versus -19%, p < 0.001), week 2 (-39% versus -21%, p = 0.02), month 1 (-42% versus -28%, p = 0.035) and month 12 (-39% versus -24%, p = 0.024). The mean absolute IOP was lower in intra- and subtenon group at week 1 (10.8 [95%CI, 8.8-14.1] versus 16.6 [95%CI, 14.1-19.0] mmHg, p < 0.001) and months 12 (13.9 [95%CI, 12.4-15.4] versus 16.7 [95%CI, 14.6-18.8] mmHg, p = 0.041). At month 6, a lower burden for IOP-lowering medication was shown for the intra- and subtenon group (0.2 ± 0.5 versus 1.0 ± 1.1, p = 0.034). The mean number of secondary needlings, which were done in 47/66 (71%) of the eyes, was lower in the intra- and subtenon group in the first year (1.9 ± 1.7 versus 1.2 ± 1.2, p = 0.03). Qualified surgical success was higher in the intra- and subtenon group (90% versus 61%, p = 0.01) after 1 year. CONCLUSION: The present study demonstrates a higher efficacy achieved with lower secondary needling rates in deeper implant positions in conjunctiva after XEN-GGM.

Longitudinal bleb morphology in anterior segment OCT after minimally invasive transscleral ab interno Glaucoma Gel Microstent implantation.

PURPOSE: Like the classic trabeculectomy, the minimally invasive, ab interno XEN Glaucoma Gel Microstent (XEN-GGM) creates a filtration bleb in the conjunctiva. The goal of this study was to investigate internal bleb morphology over time with anterior segment optical coherence tomography (AS-OCT) after XEN-GGM implantation. METHODS: In a prospective, single-centre, single-armed cohort study, blebs were characterized using AS-OCT in 78 eyes of 60 patients at day 1, at weeks 1 and 2 and at months 1, 3, 6, 9 and 12 after XEN-GGM implantation in patients with open-angle glaucoma. Morphological bleb characteristics were correlated with IOP and surgical success. RESULTS: Anterior segment optical coherence tomography data indicate early and late bleb changes in the course of 12 months. Uniform blebs in AS-OCTs showed higher IOPs at all examinations between week 1 (17.7 ± 4.8 mmHg versus 11.3 ± 7.1 mmHg, p = 0.001) and month 3 (16.4 ± 6.1 versus 13.4 ± 6.1, p = 0.04). Subconjunctival tissue separation bleb morphology was associated with lower mean IOPs during the course of 12 months (r = -0.75, p = 0.031). Predictors for surgical failure at month 12 were microcystic multiform bleb morphology in AS-OCT at month 3 (60% versus 15%, relative risk 4.0, p = 0.043) and uniform bleb morphology at month 9 (33% versus 23%, relative risk 1.4, p = 0.015). CONCLUSION: Bleb appearance after XEN surgery seems to be different to classic trabeculectomy literature. The present data suggest correlation of IOP and surgical long-term success with bleb morphology in AS-OCT. Prevalence of small diffuse cysts is directly associated with lower IOPs, while cystic encapsulation at 3 months predicts higher surgical failure.

Four-year results of a minimally invasive transscleral glaucoma gel stent implantation in a prospective multi-centre study.

IMPORTANCE: The transscleral XEN Glaucoma Gel Microstent (XEN-GGM, Allergan Plc., Parsippany, New Jersey) is implanted by a minimally invasive ab interno technique. BACKGROUND: The present study aims to assess the long-term clinical outcomes in patients after XEN-GGM implantation. DESIGN: This prospective, non-randomized, multi-centred study was conducted in three countries (Austria, Canada and Germany). PARTICIPANTS: Sixty-four consecutive eyes of 64 patients with open angle glaucoma received the XEN-GGM (63 µm) without Mitomycin C. Thirty-five (55%) were solo procedures, and 29 (45%) were combined with cataract surgery. METHODS: Visits were planned at baseline, 6 months, 1, 2, 3 and 4 years postoperatively. MAIN OUTCOME MEASURES: The main outcome measures were mean intraocular pressure (IOP), mean number of IOP lowering medication. Secondary outcome parameters were: visual acuity, visual fields and complete surgical failure (defined as presence of a secondary IOP lowering procedure or loss of light perception) at 4 years, postoperatively. RESULTS: Mean best-medicated baseline IOP was 22.5 ± 4.2 mmHg and decreased significantly to 13.4 ± 3.1 mmHg 4 years postoperatively (-40%, n = 34, P < 0.001). Mean number of IOP lowering medication decreased significantly from 2.4 ± 1.3 preoperatively to 1.2 ± 1.3 (-50%, n = 34, P < 0.001) postoperatively. Visual field mean deviation showed no significant change between preoperative and postoperative examinations. Complete surgical failure rate per year was 10%. CONCLUSIONS AND RELEVANCE: The XEN-GGM resulted in lower IOP and a reduction in medications from baseline over 4 years of follow-up. There was no detectable decrease in visual fields over the study. The surgical failure rate is comparable to other filtration surgeries.

Retinal Pericytes: Characterization of Vascular Development-Dependent Induction Time Points in an Inducible NG2 Reporter Mouse Model.

Purpose/aim of the study: In the retina, defects in pericytes (PCs) function/loss are associated with various complications; however, the exact pathological mechanisms are still not fully elucidated. Following the behavior of retina-resident PCs during health and disease will reveal new insights for both the understanding of pathological mechanisms and the development of new regenerative therapies for the treatment of retinopathies. The main goal of this study is to determine whether the NG2-reporter mouse (NG2CreERTM-eGFP) is a suitable model to study the fate of retina-resident PCs. MATERIAL AND METHODS: Vascular development-dependent reporter induction in retinal PCs was evaluated at different time points [(a) > P21, (b) < P21, and (c) P1 to > P21)] and additionally four different modes of application were tested. Reporter expression was evaluated by enhanced green fluorescent protein (eGFP) immunofluorescence by confocal microscopy and induction efficiency was calculated by analyzing NG2-expressing PCs in comparison to eGFP-labeled PCs in the three capillary layers. RESULTS: eGFP-positive PCs were detected in the three retinal capillary layers at all time points and administration routes tested. Multiple tamoxifen (TAM) applications in adult (> P21) NG2CreERTM-eGFP mice resulted in 3.59% eGFP-positive PCs. 2.37% eGFP-labeled PCs were detected after single intraperitoneal TAM injections at early postnatal days (P2/P5); however, just 1.61% PCs revealed reporter expression upon activation via the lactating mother (P4-P7). The highest number of eGFP-labeled PCs (7.09%) was detected following triple TAM administrations (P10-P12). The number of reporter-positive PCs doubled using homozygous animals. CONCLUSION: Despite low recombination efficiency in the used PC-specific fate mapping mouse model, changes in NG2 promoter activity of PCs during vascular development are indicated by single and multiple TAM inductions at different developmental time points. Nevertheless, these findings need further confirmation in up-coming studies by using homozygous NG2CreERTM-eGFP mice and additionally by mating the NG2CreERTM with a different reporter mouse to increase the low recombination efficiency.