Glucosamine is the most common nutrition supplement used in the United States. It is promoted not only as a pain reliever but also a therapy to slow osteoarthritis. Although studies with 3,800 patients with osteoarthritis of the knee or hip found that glucosamine was no better than placebo, it continues to be used for these two indications due to its perceived safety. However, reports of an increased intraocular pressure are alarming, especially in glaucoma. Glycosaminoglycans play a key role in the physiology of the cornea, conventional outflow of aqueous humor and the retina. In theory, long-term treatment with glucosamine could reach a concentration that impacts the morphology and function of ocular tissues. We recommend ophthalmologists counsel glaucoma patients about the potential risks of glucosamine and encourage cessation in uncontrolled intraocular pressure.

Purpose: To investigate the relationship of lamina cribrosa displacement to corneal biomechanical properties and visual function after mitomycin C-augmented trabeculectomy. Method: Eighty-one primary open angle eyes were imaged before and after trabeculectomy using an enhanced depth spectral-domain optical coherence tomography (SDOCT). Corneal biomechanical properties were measured with the Ocular Response Analyser before the surgery. The anterior lamina cribrosa (LC) was marked at several points in each of six radial scans to evaluate LC displacement in response to Intraocular pressure (IOP) reduction. A Humphrey visual field test (HVF) was performed before the surgery as well as three and six months postoperatively. Results: Factors associated with a deeper baseline anterior lamina cribrosa depth (ALD) were cup-disc ratio (P=0.04), baseline IOP (P= 0.01), corneal hysteresis (P= 0.001), and corneal resistance factor (P= 0.001). After the surgery, the position of LC became more anterior (negative), posterior (positive) or remained unchanged. The mean LC displacement was -42 μm (P= 0.001) and was positively correlated with the magnitude of IOP reduction (regression coefficient: 0.251, P=0.02), and negatively correlated with age (regression coefficient: - 0.224, P= 0.04) as well as baseline cup-disk ratio (Regression coefficient: -0.212,P= 0.05) Eyes with a larger negative LC displacement were more likely to experience an HVF improvement of more than 3 dB gain in mean deviation (P= 0.002). Conclusion: A lower SDOCT cup-disc ratio, younger age, and a larger IOP reduction were correlated with a larger negative LC displacement and improving HVF. Corneal biomechanics did not predict LC displacement.

Purpose: To investigate trabeculopuncture (TP) for predicting the outcome of ab interno trabeculectomy (AIT). AIT is an effective, low-risk procedure for open angle glaucoma. Despite widespread utilization, it fails in patients with an unidentified distal outflow resistance. Methods: We bisected 81 enucleated porcine eyes and perfused them for 72 hours. They were assigned to two groups: trial (n=42) and control (n=39). Intraocular pressure (IOP) was measured continuously. At 24 hours, four YAG-laser trabeculopunctures on the nasal trabecular meshwork were performed, followed by a 180° AIT at the same site at 48 hours. Eyes were divided into TP and AIT responders and non-responders; the proportion of TP responders between both AIT groups was compared. Results: Both post-TP and post-AIT IOPs were lower than baseline IOP (p=0.015 and p<0.01, respectively). The success rates of TP and AIT were 69% and 85.7%, respectively. The proportion of TP responders among AIT responders was greater than that of AIT non-responders (p<0.01). Sensitivity and specificity values of TP as predictive test for AIT success were 77.7% and 83.3%, respectively. The positive and negative predictive values were 96.6% and 38.5%, respectively. Conclusion: A 10% reduction in IOP after TP can be used as predictor for the success (>20% IOP decrease) of 180° AIT in porcine eyes.

Glaucoma is a blinding disease largely caused by increased resistance to drainage of fluid from the eye’s anterior chamber, resulting in elevated intraocular pressure (IOP). A major site of fluid outflow regulation and pathology is the trabecular meshwork (TM) at the entrance of the eye’s drainage system. We aimed to characterize the structural and functional properties of a newly developed tissue-engineered anterior segment eye culture model. We hypothesized that repopulation of a decellularized TM with non-native TM cells could restore aspects of normal TM. The decellularization protocol removed all cells and debris while preserving the ECM. Seeded cells localized to the TM region and progressively infiltrated the meshwork ECM. Cells reached a distribution comparable to control TM after four days of perfusion culture. After a perfusion rate increase challenge, tissue-engineered cultures reestablished normal IOPs (reseeded = 13.7±0.4 mmHg, decellularized = 35.2±2.2 mmHg, p < 0.0001). eGFP expressing CrFK control cells caused a high and unstable IOP (27.0±6.2 mmHg). In conclusion, we describe a readily available, storable, and biocompatible scaffold for anterior segment perfusion culture of non-native cells. Tissue-engineered organs demonstrated similarities to native tissues and may reduce the need for scarce donor globes in outflow research.

Purpose: To evaluate the efficacy and survival rates of trabectome-mediated ab interno trabeculectomy combined with non-fenestrated Baerveldt glaucoma implants (BT) in comparison to Baerveldt glaucoma implant alone (B).Method: A total of 175 eyes undergoing primary glaucoma surgery (60 eyes BT and 115 B) were enrolled in this retrospective comparative case series. Participants were identified using the procedural terminology codes. Groups were then matched using Coarsened Exact Matching (51 eyes in each group). The primary outcome measure was surgical success, defined as 5 mmHg < IOP ≤ 21 mmHg, and IOP reduction ≥ 20% from baseline, and no reoperation for glaucoma. Secondary outcome measures were intraocular pressure, the number of glaucoma medications, and best corrected visual acuity (BCVA).Results: The cumulative probability of success at one year was 61% in BT, and 50% in B. IOP decreased significantly from 23.5±2.4 mmHg at baseline to 14.1±2.7 mmHg at the final follow up in BT (P= 0.001). The corresponding numbers for B were 23.2± 2.0 and 13.9± 1.6, respectively (P= 0.001). There was no significant difference in IOP at the final follow-up (P=0.56). The number of medications at baseline was 2.3±0.3 in both groups. However, BT needed significantly fewer drops at all postoperative time intervals and used 1.1±0.3 (BT) and 2.0±0.4 eye drops (B) at the final follow-up visit (P= 0.004). No dangerous hypotony or hypertension occurred in BT.Conclusion: Similar rates of success and IOP reduction were observed in BT and B. BT needed significantly fewer glaucoma medications. Tube fenestration was not necessary in BT resulting in less postoperative hypotony and hypertension.

Purpose: We hypothesized that a recently introduced epibulbar micro-shunt (PRESERFLO, P) produces nycthemeral (24h) intraocular pressure (IOP) profiles different from ab-interno trabeculectomy (Trabectome, T). P is a flow restrictor that drains fluid into the sub-tenon space. In contrast, T increases conventional outflow, which is limited by episcleral venous pressure. Methods: In this prospective cohort, we analyzed 68 patients (34 P and 34 T) who presented for 24-h IOP monitoring 6 to 12 months after surgery. IOP and tonographic outflow facility were measured in the habitual position using a pneumatonometer. The IOP variation was considered the primary outcome measure. Glaucoma medications were also compared. Results: P had a higher baseline IOP than T (24.8±10.0 vs. 17.3±7.9 mmHg, p=0.001). Postoperatively, P and T had similar nycthemeral IOP profiles, but IOP in P was significantly lower than in T, except at 4 pm. P had a lower absolute IOP variation than T (5.8±2.6 vs. 7.1±2.7 mmHg, p=0.049). The relative IOP variation was similar in both (34.8±13.2 vs. 37.2±13.1, p=0.45) as was the tonographic outflow facility (0.35±0.23 vs. 0.26±0.18 µl/min/mmHg, p=0.097). Conclusion: Nycthemeral IOP profiles of P and T were similar, but P had lower IOPs and less variation than T. This could reflect how T, unlike P, is more impacted by habitual, positional factors, especially at night.

Purpose: To compare the standard implantation technique of a new ab externo microshunt (PRESERFLO) to a posterior technique with a small incision. The standard anterior approach (A) requires a relatively large, 6-8 mm perilimbal peritomy. In contrast, the posterior approach (P) involves only a 2-3 mm snip incision 2 mm posterior to the limbus. Methods: Charts of 126 PRESERFLO patients (54 A and 72 P) were retrospectively analyzed. Follow-up was 270 days. We compared the surgical time, intraocular pressure (IOP), number of medications, and complications. Results: The preoperative IOP in A was 21.8±8.5 mmHg and 23.9±8.1 mmHg in P (p=0.08). The surgical time for A was 26±0.8 minutes and 10±0.4 minutes for B (p<0.001). Following a low-pressure phase during the first week, A and P had an IOP value of 10.8±5.9 mmHg and 10.6±4.5 mmHg at 30 days, respectively (p=0.62). IOPs remained at this level throughout the study (all intra-group p> 0.08). There were no inter-group differences in IOP at any visit (all p-values > 0.3). Patients in A and P took 3.2 ± 1.3 and 3.3 ± 1.0 pressure-lowering medications at baseline, respectively (p=0.4). These values declined to 0.2 ± 0.6 in A and 0.3 ± 0.7 in P at 270 days. Both groups had a similar number of revisions (13 (10.3%) versus 10 (7.9%, p=0.14)) and complications (26 (20.8%) versus 31 (24.6%, all p>0.25). Conclusion: The posterior PRESERFLO insertion technique was 2.6 times faster than the standard anterior technique and yielded similar results with a large reduction in IOP and medications and a safety profile favorable over traditional filtering surgery.

Purpose: To compare ab interno trabeculectomy by trabecular meshwork excision to plasma-mediated ablation in primary open-angle glaucoma. Methods: Retrospectively collected data of TrabEx+ (TEx, n=56) and Trabectome (T, n=99) were compared by coarsened exact matching to reduce confounding and matched based on baseline IOP and age. Primary outcomes were IOP and number of glaucoma medications. Complications and need for additional glaucoma surgery were assessed. Patients were followed for up to one year. Results: 53 TEx could be matched to T. Baseline IOP was 16.5±4.6 mmHg in both; age was 73.7±8.8 and 71.5±9.9 years in TEx and T, respectively. TEx were taking more medications than T (p<0.001). IOP was reduced to 14.8±4.3 in TEx and to 13.4±3.4 in T at 6 months, and to 14.9±6.0 (p=0.13) in TEx and to 14.1±3.8 mmHg (all p<0.05) in T at 12 months. Medications were reduced at both 6 and 12 months (p< 0.05). No differences were seen between TEx and T at 6 and 12 months. In TEx, only one serious complication occurred, and two patients required further glaucoma surgery. Conclusion: Although both groups had a baseline IOP considered low for ab-interno trabeculectomy, IOP and medications were reduced further at 6 and 12 months. IOP reduction did not reach significance in TEx at 12 months. The inter-group comparison did not reveal any significant differences. Both had a low complication rate.

Pigment dispersion can lead to pigmentary glaucoma, a poorly understood condition of younger myopic eyes with fluctuating high intraocular pressure. It has been difficult to investigate its pathogenesis without a model similar to human eyes in size and behavior. Here we present a porcine ex vivo model that recreates several features of pigmentary glaucoma, including intraocular hypertension, accumulation of pigment in the trabecular meshwork, and declining phagocytosis. We found that trabecular meshwork cells regulate outflow, form actin stress fibers, and have a decreased phagocytic activity. Gene expression microarrays and a pathway analysis of TM monolayers as well as ex vivo anterior segment perfusion cultures indicated that RhoA plays a central role in regulating the cytoskeleton, motility, and phagocytosis in the trabecular meshwork, providing new insights and targets to investigate in pigmentary glaucoma.

Purpose: This study investigated the hypotensive effect of RKI-1447, a Rho kinase inhibitor, in a porcine ex vivo pigmentary glaucoma model. Methods: Twenty-eight porcine anterior chambers were perfused with medium supplemented with 1.67 × 10⁷ pigment particles/mL for 48 hours before treatment with RKI-1447 (n = 16) or vehicle control (n = 12). Intraocular pressure (IOP) was recorded and outflow facility was calculated. Primary trabecular meshwork cells were exposed to RKI-1447 or vehicle control; effects on the cytoskeleton, motility, and phagocytosis were evaluated. Result: Compared to baseline, the perfusion of pigment caused a significant increase in IOP in the RKI-1447 group (P = 0.003) at 48 hours. Subsequent treatment with RKI-1447 significantly reduced IOP from 20.14 ± 2.59 mmHg to 13.38 ± 0.91 mmHg (P = 0.02). Pigment perfusion reduced the outflow facility from 0.27 ± 0.03 at baseline to 0.18 ± 0.02 at 48 hours (P < 0.001). This was partially reversed with RKI-1447. RKI-1447 caused no apparent histological changes in the micro- or macroscopic TM appearance. RKI-1447-treated primary TM cells showed significant disruption of the actin cytoskeleton both in the presence and absence of pigment (P < 0.001) but no effect on TM migration was observed. Pigment-treated TM cells exhibited a reduction in TM phagocytosis, which RKI-1447 reversed. Conclusion: RKI-1447 significantly reduces IOP by disrupting TM stress fibers and increasing TM phagocytosis. These features may make it useful for the treatment of secondary glaucomas with an increased phagocytic load.

Objective: The Rho GTPase/Rho kinase pathway is an important target in glaucoma treatment. This study investigated the hypotensive effect of RKI-1447, a Rho kinase inhibitor developed for cancer treatment, in a porcine ex vivo pigmentary glaucoma model. Materials and Methods: Twenty-eight fresh porcine anterior chambers were perfused with pigment medium (1.67 × 10⁷ pigment particles/mL) for 48 hours before being subjected to the RKI-1447 (n = 16) or the vehicle control (n = 12). Another twelve eyes with normal medium perfusion served as the control. The intraocular pressure (IOP) was recorded at two-minute intervals and the outflow facility was calculated. To investigate the intracellular mechanism of the IOP reduction, primary trabecular meshwork cells were exposed to RKI-1447 or the vehicle control and then analyzed for changes in cytoskeleton, motility, and phagocytosis. Results: Compared to the baseline, the perfusion of pigment caused a significant increase in IOP in the RKI-1447 group (P = 0.003) at 48 hours. Subsequent treatment with RKI-1447 significantly reduced IOP from 20.14 ± 2.59 mmHg to 13.38 ± 0.91 mmHg (P = 0.02). Pigment perfusion reduced the outflow facility from 0.27 ± 0.03 at baseline to 0.18 ± 0.02 at 48 hours (P < 0.001). This was partially reversed with RKI-1447. RKI-1447 exhibited no apparent changes in the micro- or macroscopic appearance, including histology. Primary TM cells exposed to RKI-1447 showed a significant disruption of the actin cytoskeleton both in the presence and absence of pigment exposure (P < 0.001) but no effect on TM migration was observed. Pigment-treated TM cells exhibited a reduction in TM phagocytosis, which RKI reversed. Conclusions: RKI-1447 is a novel ROCK inhibitor that significantly reduces IOP by disrupting TM stress fibers and increasing TM phagocytosis. These features may make it especially useful for the treatment of secondary glaucomas with an increased phagocytosis load but also for other open angle glaucomas.

Purpose: To evaluate the efficacy and survival rates of same session ab interno trabeculectomy with the trabectome and Ahmed glaucoma valve implant (AT) in comparison to the Ahmed glaucoma valve alone (A). Method: A total of 107 eyes undergoing primary glaucoma surgery were enrolled in this retrospective comparative case series, including 48 eyes which underwent AT and 59 eyes which received A alone. Participants were identified using the procedural terminology codes, and their medical records were reviewed. The primary outcome measure was surgical success, defined as intraocular pressure (IOP) > 5 mmHg, ≤ 21 mmHg, and IOP reduction ≥ 20% from baseline at two consecutive visits after three months, no reoperation for glaucoma. Secondary outcome measures were IOP, the number of glaucoma medications, incidence of a hypertensive phase, and best corrected visual acuity (BCVA). Results: The cumulative probability of success at one year was 70% in AT, and 65% in A (p=0.85). IOP decreased significantly from 26.6 ± 10.1 mmHg at baseline to 14.7 ± 3.3 mmHg at the final follow-up in AT (p= 0.001). The corresponding numbers for A were 28.8 ± 10.2 and 16.7 ± 4.9, respectively (p= 0.001). The final IOP was significantly lower in AT (p= 0.022). The number of medications at baseline was comparable in both groups (2.6 ± 1.2 in AT and 2.5 ± 1.3 in A, p=0.851). Corresponding number at 1 year visit was 1.2±2 in AT and 2.8±1.8 in A (p=0.001). The incidence of a hypertensive phase was 18.7% in AT and 35.5% in A (p=0.05). HP resolved in only 30% of eyes. The criteria for HP resolution were fulfilled in 9 eyes (30%). There was no difference in the rate of resolution of the hypertensive phase between AT and A (33.3% and 28.5%, respectively, p=0.67). Conclusion: Ahmed glaucoma valve implant with same session trabectome surgery significantly decreased the rate of the hypertensive phase and postoperative IOP as well as the number of glaucoma medications.

Purpose: To determine whether 24-hour IOP monitoring can be a predictor for glaucoma progression and to analyze the inter-eye relationship of IOP, perfusion and progression parameters. Methods: We extracted data from manually drawn IOP curves with HIOP-Reader, a software suite we developed. The relationship between measured IOPs and mean ocular perfusion pressures (MOPP) to retinal nerve fiber layer (RNFL) thickness was analyzed. We determined the ROC curves for peak IOP (Tmax), average IOP (Tavg), IOP variation (IOPvar) and historical IOP cut-off levels to detect glaucoma progression (rate of RNFL loss). Bivariate analysis was conducted to check for various inter-eye relationships. Results: 217 eyes were included. The average IOP was 14.8±3.5 mmHg, with a 24-hour variation of 5.2±2.9 mmHg. 52% of eyes with RNFL data showed disease progression. There was no significant difference in Tmax, Tavg and IOPvar between progressors and non-progressors (all p>0.05). Except for Tavg and the temporal RNFL, there was no correlation between disease progression in any quadrant, Tmax, Tavg and IOPvar. 24-hour and outpatient IOP variables had poor sensitivities and specificities in detecting disease progression. The correlation of inter-eye parameters was moderate; correlation with disease progression was weak. Conclusion: In line with our previous study, IOP data obtained during a single visit (outpatient or inpatient monitoring) make for a poor diagnostic tool, no matter the method deployed. Glaucoma progression and perfusion pressure in left and right eyes correlated weakly to moderately with each other.

Purpose: Nycthemeral (24-hour) glaucoma inpatient intraocular pressure (IOP) monitoring has been used in Europe for more than 100 years to detect peaks missed during regular office hours. Data supporting this practice is lacking, partially because it is difficult to correlate manually drawn IOP curves to objective glaucoma progression. To address this, we deployed automated IOP data extraction tools and tested for a correlation to a progressive retinal nerve fiber layer loss on spectral-domain optical coherence tomography (SDOCT). Methods: We created and deployed a machine-learning image analysis software to extract IOP data from hand-drawn, nycthemeral IOP curves of 225 retrospectively identified glaucoma patients. The relationship between demographic parameters, IOP and mean ocular perfusion pressure (MOPP) data to SDOCT data was analyzed. Sensitivities and specificities for the historical cut-off values of 15 mmHg and 22 mmHg in detecting glaucoma progression were calculated. Results: IOP data could be extracted efficiently. The IOP average was 15.2±4.0 mmHg, nycthemeral IOP variation was 6.9±4.2 mmHg, and MOPP was 59.1±8.9 mmHg. Peak IOP occurred at 10 AM and trough at 9 PM. Disease progression occurred mainly in the temporal-superior and -inferior SDOCT sectors. No correlation could be established between demographic, IOP, or MOPP parameters and SDOCT disease progression. The sensitivity and specificity of both cut-off points (15 and 22 mmHg) were insufficient to be clinically useful. Outpatient IOPs were non-inferior to nycthemeral IOPs. Conclusion: IOP data obtained during a single visit make for a poor diagnostic tool, no matter whether obtained using nycthemeral measurements or during outpatient hours.

Purpose: To investigate the extent of anterior chamber angle circumference needed to maintain a physiological outflow facility (C). Methods: Twenty anterior segments of porcine eyes were assigned to 5 groups, each with a different degree of cyanoacrylate-mediated angle closure: 90° (n = 4), 180° (n = 4), 270° (n = 4), 360° (n = 4) and four unoccluded control eyes. The outflow facility was measured at baseline, 3, 12, 24, and 36 hours after angle closure. Outflow patterns were evaluated with canalograms and the histomorphology was compared. Results: Baseline outflow facilities of the five groups were similar (F = 0.922, P = 0.477). Complete, circumferential occlusion over 360° induced a significant decrease in facility from baseline at all time-points (P ≤ 0.023 at 3, 12, 24 and 36 hours). However, no difference from baseline was found in any of the partially-occluded (0–270°) groups (F ≥ 0.067, P ≥ 0.296 at 3, 12, 24 and 36 hours). The canalograms confirmed the extent of occlusion with flow through the unblocked regions. Histology revealed no adverse effects of blockage on the TM or aqueous plexus in the unoccluded angle portions. The unoccluded TM appeared normal. Conclusion: Cyanoacrylate-mediated angle occlusion created a reproducible angle closure model. 90° of unoccluded anterior chamber angle circumference was sufficient to maintain physiological outflow. This model may help understand how outflow can be regulated in healthy, nonglaucomatous TM.

Purpose: To analyze the five-year results of Trabectome ab interno trabeculectomy of a single glaucoma center. Method: In this retrospective interventional single-center case series, data of 93 patients undergoing ab interno trabeculotomy between September 2010, and December 2012 were included. Kaplan-Meier analysis was performed using success criteria defined as postoperative intraocular pressure (IOP) ≤21 mm Hg, or >20% reduction from preoperative IOP, and no need for further glaucoma surgery. Risk factors for failure were identified using Cox proportional hazards ratio (HR). Results: The retention rate for five years follow-up was 66%. The cumulative probability of success at 1, 2, 3, 4 and 5 years was 82.6%, 76.7%, 73.9%, 72.3%, and 67.5%. Risk factors for failure were lower baseline IOP (HR=0.27, P=0.001), younger age (HR=0.25, P=0.02), and higher central corneal thickness (HR=0.18, P= 0.01). Pseudoexfoliation was associated with a higher success rate (HR= 0.39, P=0.02). IOP was decreased significantly from 20.0±5.6 mmHg at baseline to 15.6±4.6 mmHg at 5-year follow-up (P=0.001). The baseline number of glaucoma medications was 1.8±1.2, which decreased to 1.0±1.2 medications at 5 years. Conclusion: Trabectome surgery was associated with a good long-term efficacy and safety profile in this single-center case series with a high retention rate. A higher baseline IOP, older age, thinner cornea, and pseudoexfoliation glaucoma were associated with a higher success rate.

Purpose: To evaluate three different microincisional ab interno trabeculectomy procedures in a porcine eye perfusion model. Methods: In perfused porcine anterior segments, 90 degrees of trabecular meshwork (TM) were ablated using the Trabectome (T; n = 8), Goniotome (G; n = 8), or Kahook device (K; n = 8). After 24 hours, additional 90 degrees of TM were removed. Intraocular pressure (IOP) and outflow facility were measured at 5 µL/min and 10 µL/min perfusion to simulate an elevated IOP. Structure and function were assessed with canalograms and histology. Results: At 5 µL/min infusion rate, T resulted in a greater IOP reduction than G or K from baseline (76.12% decrease versus 48.19% and 47.96%, P = 0.013). IOP reduction between G and K was similar (P = 0.420). Removing another 90 degrees of TM caused an additional IOP reduction only in T and G but not in K. Similarly, T resulted in the largest increase in outflow facility at 5 µL/min compared with G and K (first ablation: 3.41 times increase versus 1.95 and 1.87; second ablation: 4.60 versus 2.50 and 1.74) with similar results at 10 µL/min (first ablation: 3.28 versus 2.29 and 1.90 (P = 0.001); second ablation: 4.10 versus 3.01 and 2.01 (P = 0.001)). Canalograms indicated circumferential flow beyond the ablation endpoints. Conclusions: T, G and K significantly increased the outflow facility. In this model, T had a larger effect than G and K.

Purpose: To correlate outflow function and outflow tract vessel diameter changes induced by nitric oxide (NO). Methods: In a porcine anterior segment perfusion model, the effects of a nitric oxide donor (100 µM DETA-NO) on outflow facility were compared to controls (n=8 per group) with trabecular meshwork (TM) and after circumferential ab interno trabeculectomy (AIT). Outflow structures were assessed with spectral domain optical coherence tomography (SD-OCT) before and after NO, or an NO synthase inhibitor (100 µM L-NAME) and the vasoconstrictor, endothelin-1 (100 pg/mL ET-1). Scans were processed with a custom macro script and aligned for automated reslicing and quantification of cross-sectional outflow tract areas (CSA). Results: The facility increased after DETA-NO (0.189±0.081 μL/min·mmHg, p=0.034) and AIT (0.251±0.094 μL/min·mmHg, p=0.009), respectively. Even after AIT, DETA-NO increased the facility by 61.5% (0.190±0.074 μL/min·mmHg, p=0.023) and CSA by 13.9% (p<0.001). L-NAME + ET-1 decreased CSA by -8.6% (p<0.001). NO increased the diameter of focal constrictions 5.0±3.8 fold. Conclusions: NO can dilate vessels of the distal outflow tract and increase outflow facility in a TM-independent fashion. There are short, focally constricting vessel sections that display large diameter changes and may have a substantial impact on outflow.

Purpose: To investigate whether microsurgical excision of trabecular meshwork (TM) in an ex vivo pigmentary glaucoma model can normalize the hypertensive phenotype. Methods: Eight eyes of a porcine pigmentary glaucoma model underwent 90° of microsurgical TM excision with an aspirating dual-blade (Goniotome (G)). 24 hours later, an additional 90° of TM were removed. Anterior segments with sham surgeries served as the control (C). Outflow facility and intraocular pressure (IOP) were analyzed. Histology with hematoxylin and eosin (H&E) was obtained. Results: After the first 90° TM excision, IOP was significantly lower in G (10.23±2.39 mmHg, n=7) than C (20.04±1.97mmHg, n=8, P<0.01). Outflow facility in G (0.38±0.07 µl/min/mmHg) was higher than C (0.16±0.02 µl/min/mmHg, P<0.01). After the second 90° TM excision, IOP in G (6.46±0.81 mmHg, n=7) was significantly lower than C (20.25±1.66 mmHg, n=8, P<0.001), while the outflow facility in G (0.50±0.05 µl/min/mmHg, n=7) was higher than C (0.16±0.01 µl/min/mmHg, n=8, P<0.001). Compared to the first excision, excision of an additional 90° did not change of IOP (P=0.20) or outflow facility (P=0.17) further. Conclusion: Excision of 90° of TM in a pigmentary glaucoma model using an aspirating dual-blade decreased IOP and increased outflow facility. Translational Relevance: Microsurgical TM excision over 90° can effectively restore outflow in pigmentary glaucoma.

Purpose: To create a highly balanced comparison of ab interno trabeculectomy (Trabectome, AIT) and trabecular bypass stenting (iStent, TBS).Setting: Eye and Ear Institute, Pittsburgh, Ross Eye Institute, Buffalo, and Glaucoma Associates of Texas, Dallas, USA.Design: Retrospective Exact Matching analysis.Methods: AIT and TBS patients were included from three large glaucoma practices. The primary outcome measure was the unmedicated IOP ≤ 21 mmHg at 2-year follow-up visit. A secondary measure was unmedicated IOP reduction ≥ 20% at 2 years. Patients were matched by baseline IOP, the number of glaucoma medications and glaucoma type using Exact Matching and by age using Nearest Neighbor matching. Patients without a close match were excluded. All surgeries were combined with phacoemulsification. Results: 154 AIT and 110 TBS eyes were analyzed. 48 AIT patients were exactly matched to 48 TBS patients. Both groups had a baseline IOP of 15.3±3.1 mmHg. At 24 months, the mean IOP was 13.9±3.3 for AIT versus 16.8±2.8 mmHg for TBS (p=0.04), while the number of medications was 0.7±1.0 for AIT versus 1.7±1.2 for TBS (p=0.04). The proportion of subjects achieving IOP ≤ 21 mmHg without medications at 24 months was 53% in AIT versus 16.6% in TBS (P < 0.05). At 24-month follow up 17.6% of patients in AIT had ≥ 20% IOP reduction without medication versus no patient in TBS. Conclusions: An Exact Matching comparison of AIT and TBS demonstrated greater IOP reduction with fewer medications in AIT.