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

Anterior-Segment Optical Coherence Tomography-Based Evaluation of the Journey of a Bleb in the Early Postoperative Period

Introduction In the early postoperative period following trabeculectomy, monitoring the journey of bleb formation is crucial for assessing surgical success. Anterior-segment optical coherence tomography (AS-OCT) emerges as a powerful tool in this pursuit, offering high-resolution imaging of bleb morphology and dynamics. This study aims to evaluate the internal structure of blebs through their maturation phases using AS-OCT. Methods Fifty-five eyes undergoing trabeculectomy were enrolled in a prospective observational study. Serial AS-OCT examinations were done on day 1, week 1, week 3, and week 6 postoperatively; bleb parameters were calculated and correlated with intraocular pressure (IOP). Results IOP control was seen in 45 eyes six months of post-trabeculectomy. Multiform bleb wall reflectivity (BWR) statistically correlates with the success of trabeculectomy. Blebs were successful if BWR showed no change from day 1 to week 6. BWR remained the same on all follow-ups if week 1 bleb wall thickness (BWT) was less than 129.5 microns with 82.6% sensitivity and 83.3% specificity. The cumulative hazard of change in BWR is estimated to be approximately 5.6%, 15.7%, and 17.9% at week 1, week 3, and week 6 follow-ups, respectively. Conclusions Successful blebs showed consistent BWR from day 1 to week 6 of follow-up. Serial AS-OCT examination for changes in BWR in early stages can be done to predict the fate of bleb. The maximum change in BWR occurs between the week 1 and week 3 follow-up periods requiring close follow-up.

Superonasal vs Inferonasal Subconjunctival Gel Stent Placement in Patients with Glaucoma

Aim and background

To compare the safety and efficacy of subconjunctival gel stent implantation in the superonasal (SN) vs inferonasal (IN) quadrants in the treatment of glaucoma.

Materials and methods

Patients with a history of IN (n = 29) or SN, (n = 96) gel stent placement with ≥3 months of follow-up were included. Intraocular pressure (IOP) and the number of glaucoma medications were collected preoperatively and postoperatively at months 1, 3, 6, and 12. Safety measures included the number of bleb needlings, complication rate, and additional surgeries.

Results

Mean baseline IOP was 32.4 ± 11.7 mm Hg in the IN group and 21.6 ± 9.2 mm Hg in the SN group (p < 0.01). IOP was similar between groups at 3 months (IN = 15.8, SN = 15.6, p = 0.45), 6 months (IN = 17.4, SN = 15, p = 0.13), and 12 months (IN = 17.9, SN = 14.7, p = 0.15) follow-up. The number of glaucoma medications was also similar at 3 months (p = 0.31), 6 months (p = 0.24), and 12 months (p = 0.39) follow-up. Bleb needling rates were similar with 51.7% (15/29) in the IN group vs 42.7% (41/96) in the SN group (p = 0.39) and subjects requiring further surgery were 17.2% (5/29) in the IN group vs 24.0% (23/96) in the SN group (p = 0.45).

Conclusion

Both IN and SN subconjunctival gel stent placements provide favorable safety and efficacy when treating open-angle glaucoma, with a meaningful decrease in medication use and IOP.

Clinical significance

Implantation of the subconjunctival gel stent in the IN quadrant is an effective and safe alternative to superior implantation in refractory glaucoma.

How to cite this article

Vander Zee BL, Wilson C, Berdahl JP, et al. Superonasal vs Inferonasal Subconjunctival Gel Stent Placement in Patients with Glaucoma. J Curr Glaucoma Pract 2024;18(2):63-67.

One-Year Outcomes of Ab Externo XEN45 Gel Stent Implantation with an Open Conjunctiva Approach in Patients with Open-Angle Glaucoma

PURPOSE

This study aimed to evaluate the 1-year surgical outcomes of XEN45 gel stent implantation with an open conjunctiva approach in patients with open-angle glaucoma (OAG).

METHODS

This retrospective cohort study included 19 eyes of 19 patients who underwent XEN45 gel stent implantation with an open conjunctival approach. Surgical success was defined by intraocular pressure (IOP) ≤18 mmHg and one of the following: IOP reduction ≥30% or reduction of two glaucoma medications with final IOP if baseline IOP ≤18 mmHg. The cumulative probability of success rate was analyzed using Kaplan-Meier survival analysis. Cox proportional hazard regression analysis was used to assess prognostic factors for surgical failure.

RESULTS

IOP reduced from 32.37 ± 12.08 mmHg preoperatively to 15.14 ± 2.25 mmHg at 1 year (p = 0.001). The number of glaucoma medication reduced from 3.89 ± 0.32 preoperatively to 0.86 ± 1.35 at 1 year (p = 0.001). The success rates were 78.9% at 6 months and 73.7% at 1 year. Eyes with bleb horizontal extent ≥2 clock hours at 1 month postoperatively had a significantly higher success rate (log-rank test, p < 0.001). Greater bleb horizontal extent at 2 weeks and 1 month postoperatively was associated with a lower surgical failure rate (2 weeks: hazard ratio, 0.119; p = 0.024; 1 month: hazard ratio, 0.046; p = 0.007). Bleb needling and additional glaucoma surgeries were necessary in 10 (52.6%) and five eyes (26.3%), respectively.

CONCLUSIONS

XEN45 gel stent implantation with the open conjunctiva approach is effective in reducing IOP and glaucoma medication for over 1 year in patients with OAG.

[Bleb morphology using optical coherence tomography : After primary implantation of XEN gel stent and open conjunctival revision]

BACKGROUND

The implantation of a XEN gel stent is an innovative method for filtration surgery using an ab interno approach. The morphological evaluation of the resulting bleb is decisive for surgical success. Bleb revision is frequently needed after XEN implantation and might affect the bleb morphology. Aim of this study was to examine bleb morphology using anterior segment OCT (AS-OCT) and analyze the morphological differences of blebs after primary XEN implantation and after bleb revision.

MATERIAL AND METHODS

Included were eyes that underwent XEN implantation (Pr-X) or bleb revision after XEN (Re‑X group). An AS-OCT of blebs was performed and images were classified using a novel classification system (the Jenaer bleb grading system, JBGS). Frequency of different tomographic patterns (M) and their correlation with intraocular pressure (IOP) were analyzed.

RESULTS AND DISCUSSION

A total of 69 eyes (40 in the Pr‑X and 29 in the Re‑X groups) were included. At the conjunctival level, the most common M in both groups was subconjunctival spaces (M-C2) followed by intraconjunctival cysts (C1) and no conjunctival changes (C0). No differences of frequencies between the two groups or of IOP between the three Ms were seen. At the tenon level, the most commonly seen Ms in the Pr‑X group were hyporeflective and cavernous changes (M-T2, T3) followed by no changes (M0) and hyperflective changes (T1). In the Re‑X group, the M‑T1 and T2 were most commonly seen followed by T3 and T0. The M‑T2 and T3 in the Pr‑X group and the M‑T1 and T2 in the Re‑X group correlated with lower IOP. An episcleral lake (M-ES1) was seen significantly less frequently in the Pr‑X group compared with Re‑X group where it correlated with lower IOP CONCLUSION: The hyperreflective changes at the tenon level and the presence of an episcleral lake were seen more frequently following bleb revision compared with primary XEN implantation and correlated with lower IOP. The interpretation of bleb morphology using AS-OCT should only be done considering the surgical approach used.

Intraocular Pressure and Medication Changes Associated with Xen Gel Stent: A Systematic Review of the Literature

The Xen gel stent (Allergan Inc, an AbbVie company; Dublin, Ireland) was conceived as an option for patients requiring modest IOP reduction but for whom trabeculectomy was not yet indicated. As with any glaucoma surgery, establishing criteria for patient selection and identifying factors that contribute to a high likelihood of success are important. To help guide clinical decision-making, a systematic review of published studies on the gel stent was performed, with the goal of understanding postoperative outcomes based on clinical and patient factors. Results were organized around a series of pertinent clinical questions based on scenarios encountered in clinical practice. Criteria for including studies were intentionally broad, with the objective of simulating the diverse population of glaucoma patients encountered in real-world practice. Outcomes for IOP and medication reduction postoperatively were assessed in various analyses, including in eyes with various glaucoma types and severity; in eyes naïve to surgery as well as those with a history of prior incisional glaucoma surgery; and when surgery was performed as a standalone procedure or at the time of cataract surgery. The results of each of the various analyses were consistent in demonstrating that successful gel stent surgery achieved a postoperative IOP of approximately 14.0 mm Hg and reduction to fewer than 1 glaucoma medication. Additional data are shown on outcomes by method of implant (ab interno vs ab externo); intraoperative use of antifibrotics; and rates of needling in published studies.

Anterior Segment-Optical Coherence Tomography Bleb Morphology Comparison in Minimally Invasive Glaucoma Surgery: XEN Gel Stent vs. PreserFlo MicroShunt

Background: The purpose of this study is to compare the morphology of six-month follow-up blebs created by a subconjunctival glaucoma surgical device (XEN45) to those created by a PreserFlo MicroShunt with a sub-Tenon insertion, utilizing AS-OCT. Methods: A retrospective study of 29 eyes who underwent XEN45 implantation and 29 eyes who underwent PreserFlo MicroShunt implantation. The patients were analyzed at 24 h, 1 week, 1 month, 3 months and 6 months. At each visit, the maturation and morphological alterations of the blebs were observed, as well as connections with the IOP. Results: In both groups, IOP showed significant reduction at all follow ups (p < 0.0001). In XEN group, the most common bleb morphology in the immediate postoperative was the subconjuntival separation type (42%) followed by the uniform type (34%), with a trend inversion at 6 month follow up (51% of uniform type). On the contrary, the most common morphology after PreserFlo was the multiple internal layer (55%), which showed a tendency to reduce over time and was substituted by the microcystic multiform, whose percentage increased over time (17% at day 1 vs. 44% at month 6). Uniform appearance was associated by the posterior episcleral fluid (PEF) lake presence. Both horizontal and vertical diameters significantly increased over time. Conclusion: XEN and PreserFlo implantation resulted in the production of diffuse blebs with different characteristics, which may influence IOP lowering capacity and bleb revisions necessity over time.

Anterior segment imaging in minimally invasive glaucoma surgery - A systematic review

Minimally invasive glaucoma surgery (MIGS) has grown in popularity over the past decade. This systematic review explores the peri-operative and intraoperative application of anterior segment imaging to maximize the efficacy and safety of MIGS. A review of the PubMed, EMBASE and CINAHL databases was conducted, with inclusion criteria restricted to MIGS that had received United States Food and Drug Administration (FDA) premarket approval, FDA 510(K) premarket notification, or were listed as a class 1 device exempt from FDA approval or notification. 21 manuscripts from 21 unique studies were identified pertaining to MIGS devices including the XEN Gel Stent, Trabectome, iStent Inject, 1st-generation iStent and the Kahook Dual Blade (KDB). Anterior segment imaging modalities included anterior segment optical coherence tomography (AS-OCT), ultrasound biomicroscopy (UBM), aqueous angiography, OCT volumetric scans and in vivo confocal microscopy. Identification and evaluation of aqueous outflow pathways before and after MIGS have potential for improving patient preoperative patient selection and postoperative outcomes. Intraoperative imaging potentially provides the resolution needed for good visualization of angle anatomy and accurate evaluation of surgical endpoints in angle-based MIGS. Anterior segment imaging has been used to identify procedural complications, provide objective information on implant location in relation to surrounding anatomy, assess the post-implantation structural impact of MIGS devices and manage bleb failure and scarring. Technical difficulties in incorporating imaging modalities into the surgical microscope, variable quality of images and optical interference from ocular structures or surgical instruments are remaining barriers, which discourage the widespread clinical use of this technology.

Does mitomycin-C concentration have any influence on XEN45 gel stent outcomes in a real-world setting?

BACKGROUND

To compare the effectiveness and safety of XEN45 implanted with mitomycin-C (MMC) 0.01% versus (vs) XEN45 implanted with MMC 0.02%.

METHODS

Retrospective and single-center study conducted on consecutive patients with open-angle glaucoma or ocular hypertension who underwent XEN45-implant, either alone or in combination with cataract surgery. The primary end-point was the mean change in intraocular pressure (IOP) from baseline to the last follow-up visit.

RESULTS

Fifty-five patients (63 eyes) were included. Thirty-seven (58.7%) eyes underwent surgery with MMC 0.01% and 26 (41.3%) ones with MMC 0.02%. In the overall study sample, the mean (standard error) IOP was significantly lowered from 17.6 (0.7) mm Hg at baseline to 12.6 (0.3) mm Hg at month 12. The IOP was significantly lowered from 17.3 (15.4 to 19.2) mm Hg and 17.9 (16.1 to 17.8) mm Hg at baseline to 12.3 (11.3 to 13.3) mm Hg and 13.1 (12.3 to 13.9) mm Hg at month 12 in the MMC 0.01% and MMC 0.02% groups, respectively; p < 0.0001 each. The mean number of ocular-hypotensive medications significantly decreased from 2.1 (1.9 to 2.3) at baseline to 0.2 (0.04 to 0.3) at month 12, p < 0.0001, with no significant differences between MMC 0.01% and MMC 0.02% groups, p = 0.5181. At month 12, 50 (80.6%) eyes had functioning blebs. Regarding safety, 18 (28.6%) eyes have experience adverse events.

CONCLUSION

XEN45, either alone or in combination with cataract surgery, showed a good effectiveness and safety profile. MMC dose had no influence on the IOP lowering, which may support the use of the lowest dose.

Bleb Analysis Using Anterior Segment Optical Coherence Tomography and Surgical Predictors of XEN Gel Stent

Purpose

To determine the early predictors of surgical success 6 months after XEN surgery among clinical parameters, including anterior segment optical coherence tomography (AS-OCT).

Methods

A total of 31 eyes with medically uncontrolled primary open-angle glaucoma or pseudoexfoliation glaucoma was enrolled retrospectively. Using AS-OCT, XEN tip location was categorized into intraconjunctival, intratenon, or uviform at day 1 and blebs were classified into no or low, high sparse, high thick, cystic, or mixed walls at month 6. Using slit-lamp photography, blebs were classified into no or low, localized avascular, diffuse avascular, localized vascular, or diffuse vascular blebs at month 6. Surgical success was defined as an intraocular pressure (IOP) of less than 14 mm Hg.

Results

Intraconjunctival and intratenon locations of the tip mostly created a high sparse wall, whereas the uviform type mostly created no or low wall and no or low bleb. The uviform type was linked to pseudoexfoliation glaucoma. A high sparse wall and diffuse avascular bleb showed a lower mean IOP than a high thick wall and localized vascular bleb. In the multivariate analysis, female sex and IOP at week 1 were early predictors of surgical success (8.45 times and 33.1% per 1 mm Hg-decrease, respectively).

Conclusions

Bleb evaluation using AS-OCT is valuable to correlate tip location and bleb morphology with clinical profiles, considering that a lower early postoperative IOP is linked to surgical success.

Translational Relevance

Bleb analysis using AS-OCT on day 1 could help to predict bleb morphology after 6 months, which is important to maintain the functioning bleb in the longer term.

Anterior-segment optical coherence tomography of filtering blebs in the early postoperative period of ab externo SIBS microshunt implantation with mitomycin C: Morphological analysis and correlation with intraocular pressure reduction

PURPOSE

To analyse the morphological evolution of filtering blebs with anterior-segment OCT (AS-OCT) and its correlation with intraocular pressure after ab externo SIBS microshunt implantation with mitomycin C (MMC) during a 3-month follow-up period.

METHODS

Twenty-eight filtering blebs of 28 patients with open-angle glaucoma were measured horizontally and vertically in the sub-Tenon space with AS-OCT after ab externo SIBS microshunt implantation with MMC. The intraocular pressure (IOP) was monitored simultaneously at each visit. Maturation of and morphological changes in the blebs and correlations with the IOP were recorded.

RESULTS

The average median preoperative IOP of 20.7 (range, 12-30) mmHg decreased to 8.5 (range, 4-17), 8.9 (range, 5-17), 10.4 (range, 8-16) and 10.9 (range, 9-15) mmHg at 24 hr, 1 week, 1 month and 3 months, respectively (p < 0.001). A multiform morphology on AS-OCT prevailed at all time points, with a 3.5% rate of a uniform bleb morphology at the first week. The horizontal and vertical diameters of the blebs increased from baseline to the third month. The horizontal expansion (406 ± 127 μm on day 7, p = 0.04, 712 ± 211 μm on day 30, p = 0.02 and 952 ± 218 μm on day 90, p < 0.001) was greater than the vertical expansion (16 ± 18 μm, p = 0.3 on day 1, 63 ± 27 μm, p = 0.02 on day 30 and 137 ± 34 μm, p < 0.001 on day 90) without correlation with the IOP (r = -0.3, p = 0.2).

CONCLUSION

Anterior-segment OCT (AS-OCT) of the filtering blebs formed after ab externo SIBS microshunt implantation showed progressive horizontal and vertical expansion of the blebs in the sub-Tenon space, with a significant peak at the first month not significantly correlated with the decrease in the IOP.

Outcomes of XEN Gel Stent Implantation in the Inferonasal Quadrant after Failed Trabeculectomy

Aim and objective

To evaluate the efficacy and safety of XEN stent implantation in the inferonasal quadrant after prior failed trabeculectomy.

Materials and methods

Fourteen open-angle glaucoma patients with prior failed trabeculectomy were recruited to this retrospective study. Implantation of the stent was performed as a stand-alone procedure. The mean follow-up duration was 14.2 months. Best-corrected visual acuity, intraocular pressure (IOP), number of medications, complications, and the requirement for additional procedures were among the outcome measures recorded.

Results

Mean IOP reduced by 49.3% from 24.14 ± 2.74 mm Hg preoperatively to 12.23 ± 2.89 mm Hg at month 12 (p < 0.001). Medication usage reduced from 3.71 ± 0.47 medications preoperatively to 1.31 ± 1.55 at month 12 (p = 0.003). Adverse events included transient slight intracameral hemorrhage (5 eyes, 35.7%), second trabeculectomy required (2 eyes, 14.3%), and numerical hypotony (IOP <5 mm Hg, in 3 cases, 21.4%), all of which resolved spontaneously. Six eyes (42.8%) required postoperative bleb needling to further reduce IOP. There were no cases of vision loss, stent exposure, hypotony, lower eyelid malposition, bleb dysesthesia, or bleb-related infection.

Conclusion

XEN gel stent implantation in the inferonasal quadrant can be considered a viable surgical option for patients with a history of previously failed trabeculectomy requiring further IOP lowering.

Clinical significance

To the best of our knowledge, this is the first case series describing the outcome of inferonasal implantation of XEN gel stent following failed trabeculectomy.

How to cite this article

Düzgün E, Olgun A, Karapapak M, et al. Outcomes of XEN Gel Stent Implantation in the Inferonasal Quadrant after Failed Trabeculectomy. J Curr Glaucoma Pract 2021;15(2):64–69.

Evaluation of the Ultrastructural and In Vitro Flow Properties of the PRESERFLO MicroShunt

Purpose

To measure the in vitro flow properties of the PRESERFLO implant for comparison with the theoretical resistance to flow.

Methods

The PRESERFLO was designed to control the flow of aqueous humor according to the Hagen-Poiseuille (HP) equation. Scanning electron microscopy (SEM) was performed to analyze the ultrastructure, and flow measurements were carried out using a gravity-flow setup.

Results

SEM images of the PRESERFLO showed luminal diameters of 67.73 × 65.95 µm and 63.66 × 70.54 µm. The total diameter was 337.2 µm, and the wall was 154 µm wide. The theoretical calculation of the resistance to flow (R) for an aqueous humor (AH) viscosity of 0.7185 centipoises (cP) was 1.3 mm Hg/(µL/min). Hence, assuming a constant AH flow of 2 µL/min, the pressure differential across the device (ΔP) was estimated to be 2.6 mm Hg. The gravity-flow experiment allowed us to measure the experimental resistance to flow, which was R_E = 1.301 mm Hg/(µL/min), in agreement with the theoretical resistance to flow R given by the HP equation.

Conclusions

The experimental and theoretical flow testing showed that the pressure drop across this device would not be large enough to avoid hypotony unless the resistance to outflow of the sub-Tenon space was sufficient to control the intraocular pressure in the early postoperative period.

Translational Relevance

The fluid properties of glaucoma subconjunctival drainage devices determine their specific bleb-forming capacity and ability to avoid hypotony and therefore their safety and efficacy profile.

Latanoprost eye drops induce conjunctival lymphatic vessel development

AIM

To investigate the effect of latanoprost eye drops on the conjunctival lymphatics.

METHODS

Twenty-four healthy New Zealand White rabbits weighing 1.5 to 2.0 kg were randomly divided into three groups: latanoprost group (n=8) administered with latanoprost eye drops once a day for 2mo, carteolol group (n=8) administered with carteolol eye drops once a day for 2mo, and control group (n=8) without any treatment. The conjunctival tissues in the three groups were extracted to investigate the expression levels of 5'-nucleotidase (5'-Nase) by Western blot, reverse transcription-polymerase chain reaction (RT-PCR), and immunofluorescence staining, respectively.

RESULTS

The protein expression level of 5'-Nase was significantly higher in latanoprost group than carteolol group (F=231.175, P<0.001) and control group (P<0.001), while there was no significant difference between the carteolol group and the control group (P>0.05). The mRNA expression level of 5'-Nase in the latanoprost group was also significantly higher than carteolol group (F=71.169 P<0.005) and control group (P<0.005). The conjunctival lymphatics were positive immunofluorescence stained with the 5'-Nase antibodies in the latanoprost group and not stained in the control group.

CONCLUSION

Latanoprost eye drops can induce conjunctival lymphangiogenesis which may be concerned in clinical implications.

Minimally Invasive Glaucoma Surgery: A Critical Appraisal of the Literature

Micro- or minimally invasive glaucoma surgeries (MIGS) have been the latest addition to the glaucoma surgical treatment paradigm. This term refers not to a single surgery, but rather to a group of distinct procedures and devices that aim to decrease intraocular pressure. Broadly, MIGS can be categorized into surgeries that increase the trabecular outflow [Trabectome, iStent (first and second generations), Hydrus microstent, Kahook Dual Blade and gonioscopy-assisted transluminal trabeculotomy], surgeries that increase suprachoroidal outflow (Cypass microstent and iStent Supra), and conjunctival bleb-forming procedures (Xen gel stent and InnFocus microshunt). Compared to traditional glaucoma surgeries, such as trabeculectomy and glaucoma drainage device implantation (Ahmed, Baerveldt, and Molteno valves), MIGS are touted to have less severe complications and shorter surgical time. MIGS represent an evolving field, and the efficacy and complications of each procedure should be considered independently, giving more importance to high-quality and longer-term studies.

Confocal Microscopy and Anterior Segment Optical Coherence Tomography Imaging of the Ocular Surface and Bleb Morphology in Medically and Surgically Treated Glaucoma Patients: A Review

Glaucoma patients often suffer from ocular surface disease (OSD) caused by the chronic administration of topical anti-glaucoma medications, especially in cases of long-term therapy with preserved or multiple drugs. Additionally, glaucoma surgery may determine ocular surface changes related to the formation and location of the filtering bleb, the application of anti-mitotic agents, and the post-operative wound-healing processes within the conjunctiva. Recently, several studies have evaluated the role of advanced diagnostic imaging technologies such as in vivo confocal microscopy (IVCM) and anterior segment-optical coherence tomography (AS-OCT) in detecting microscopic and macroscopic features of glaucoma therapy-related OSD. Their clinical applications are still being explored, with recent particular attention paid to analyzing the effects of new drug formulations and of minimally invasive surgical procedures on the ocular surface status. In this review, we summarize the current knowledge about the main changes of the ocular surface identified at IVCM and AS-OCT in glaucoma patients under medical therapy, or after surgical treatment.

XEN45 real-life evaluation: Survival analysis with bleb needling and major revision outcomes

PURPOSE

To evaluate real-life outcomes of XEN45 stent surgery including bleb needling (BN) and surgical bleb revision (SBR).

METHODS

Retrospective analysis of all XEN45 gel stents implanted in a tertiary glaucoma center with a minimum follow-up of 6 months. The main outcomes were intraocular pressure (IOP), the number of glaucoma medications, postoperative maneuvers like BN, and subsequent SBR. Success was defined as IOP ⩽ 18 and 20% reduction (criterion A), ⩽15 and 25% reduction (criterion B), and ⩽12 mmHg and 30% reduction (criterion C) reached with (qualified) or without (complete) medications at the last visit. Complete failure was defined as additional glaucoma surgery, loss of light perception, or sight-threatening complications. Multivariable Cox regression and Kaplan-Meier survival estimates tests were performed.

RESULTS

Fifty-eight eyes with either stand-alone or combined Phaco-XEN surgery were included. Complete success by the different definitions was 50.0% (95% confidence interval, 5.8%-84.5%) (A), 50.0% (5.8%-84.5%) (B), and 25% (0.9%-66.5%) (C) whereas qualified success was 38.3% (1.6%-80.1%), 31.7% (2.0%-71.4%), and 0%, respectively, at the 24-months visit. 30% of cases underwent BN with 5-Fluorouracil, and SBR was performed in 17.5% of eyes. Low IOP levels at 1-month and early BN were significantly associated with success. The highest chance of failure was achieved in the combined Phaco-XEN group undergoing SBR.

CONCLUSIONS

In our real-life setting, the first month IOP was associated with greater success rates. Although BN obtained improved IOP values, SBR was associated with a greater bleb survival in the stand-alone XEN group. Both BN and SBR had poor outcomes in the combined Phaco-XEN group.

Five-year results of non-penetrating deep sclerectomy with demineralized cancellous bone xenogenically derived collagen glaucoma implant

PURPOSE

To investigate the long-term effectiveness of non-penetrating deep sclerectomy (NPDS) with xenogenically derived cancellous bone collagen glaucoma implant (XCB-CGI) implantation in patients with primary open-angle glaucoma (POAG).

MATERIALS AND METHODS

Retrospective chart review of patients with POAG stages 2 and 3 was treated with NPDS and XCB-CGI. Follow-up was at 6 months, 1, 2, 3, 4 and 5 years after surgery. Main outcomes were intraocular pressure (IOP) and medication burden. Secondary outcomes were visual acuity, corneal hysteresis (CH), visual field (VF) and optical coherence tomography (OCT) parameter analysis.

RESULTS

Among 71 patients (71 eyes), the mean age was 72.7 ± 9.8. Average initial IOP was 27.7 ± 7.9 and average initial med load was 2.36 ± 0.99. At 6 months, 1, 2, 3, 4 and 5 years, the average IOP was 14.9 ± 3.3 mm Hg (46.2% reduction), 15.3 ± 4.0 mm Hg (44.7% reduction), 14.2 ± 3.8 mm Hg (48.7% reduction), 15.2 ± 3.3 mm Hg (45.0% reduction), 15.5 ± 3.3 mm Hg (44.0% reduction) and 14.2 ± 2.8 mm Hg (48.7% reduction), respectively. In 5 years, the success rate was 34% and 67%, without, and with medications (1.8 ± 0.8 meds required), respectively. Visual acuity was not significantly different (P > .05) at all follow-up visits from baseline. Mean CH increased by 2.1 ± 0.8 (P = .05). No glaucomatous deterioration of the VF and OCT parameters was detected in 56 eyes at the 5-year follow-up.

CONCLUSION

NPDS with XCB-CGI implantation is an effective procedure to normalize the level of IOP, stabilize glaucomatous changes and decrease the number of meds needed for glaucoma control.

Aqueous humour outflow imaging: seeing is believing

Elevated intraocular pressure (IOP) is the primary risk factor for blindness in glaucoma. IOP is determined by many factors including aqueous humour production and aqueous humour outflow (AHO), where AHO disturbance represents the primary cause of increased IOP. With the recent development of new IOP lowering drugs and Minimally Invasive Glaucoma Surgeries (MIGS), renewed interest has arisen in shedding light on not only how but where AHO is occurring for the trabecular/conventional, uveoscleral/unconventional, and subconjunctival outflow pathways. Historical studies critical to understanding outflow anatomy will be presented, leading to the development of modern imaging methods. New biological behaviours uncovered by modern imaging methods will be discussed with relevance to glaucoma therapies emphasized.

Effective treatment of a normal-tension glaucoma patient with bilateral ab externo XEN Gel Stent implantation

Purpose

To provide the first report of effective use of bilateral XEN Gel Stent implantation using an ab externo open-conjunctival approach designed to improve bleb function and meet the uniquely low intraocular pressure requirements of a Japanese patient with normal-tension glaucoma refractory to topical medical therapy.

Observations

A 54-year-old phakic Japanese woman with severe normal-tension glaucoma on maximally tolerated medical therapy of four topical agents presented with above-goal intraocular pressures and new medication intolerances. She underwent bilateral ab externo open-conjunctival XEN Gel Stent implantation with tenectomy and sub-Tenon's injection of 40μg of mitomycin-C, which resulted in reduction of intraocular pressures by 41.2 and 28.6% to 10 and 10 mmHg in the right and left eyes, respectively at the most recent visit. Postoperatively, a diffuse filtering bleb with good morphology developed in both eyes. The procedure has so far allowed for complete cessation of all four topical medications for up to eight months following surgery without any serious complications.

Conclusions

This case illustrates the potential of Xen Gel Stent implantation through an ab externo, open-conjunctival approach to be an effective, simple alternative to trabeculectomy to meet the unique low-pressure requirements of normal-tension glaucoma patients with practical and safety benefits of a micro-invasive approach.

Angiographic biomarkers of filtering bleb function after XEN gel implantation for glaucoma: an optical coherence tomography-angiography study

PURPOSE

To evaluate, using optical coherence tomography-angiography (OCT-A), the vascular features of good bleb function after XEN gel implantation (XGI) for uncontrolled glaucoma.

METHODS

Forty-three patients (43 eyes), who underwent XGI, were enrolled. According to the intraocular pressure (IOP) reduction, patients were classified into Group 1 (21 eyes; success) and Group 2 (22 eyes; failure). Optical coherence tomography-angiography (OCT-A) was performed to image the vascularization of the conjunctival bleb-wall. The main outcomes were as follows: vessel displacement areas (VDAs), major vessel displacement area (MVDA; mm2 ), non-flow whole area (NFWA; mm2 ) and bleb-wall vessel density (BVD; %). Co-registered B-scans were also considered to evaluate the bleb-wall cyst-like structure density and area (BCSD, cysts/mm2 ; BCSA, mm2 ), and the bleb-wall thickness (BT, µm).

RESULTS

Mean postoperative follow-up was 7.5 ± 0.14 months; Group 1 and 2 IOP were 14.0 ± 2.5 and 25.3 ± 2.1 mmHg, respectively (p < 0.001). Greater VDA (p < 0.001), MVDA (p = 0.046) and NFWA (p = 0.001) values, and lower BVD (p < 0.001) was found in Group 1 compared to Group 2. Group 1 showed higher BSCD, BSCA and BT values compared to Group 2 (p < 0.001). Postoperative IOP positively correlated with BVD (r = 0.567; p = 0.003), but negatively with VDAs, MVDA (r = -0.581, p = 0.002; r = -0.619, p = 0.001, respectively), BCSD, BCSA (r = -0.580; p = 0.002; r = -0.664; p < 0.001) and BT (r = -0.627, p = 0.001).

CONCLUSION

Successful filtration blebs after XGI present numerous and large areas of vessel displacement within the bleb-wall, along with a rarefied vascular network. These OCT-A features can be considered angiographic biomarkers of a good aqueous humour percolation through the bleb-wall layers.

Functional, structural, and molecular identification of lymphatic outflow from subconjunctival blebs

The purpose of this study is to evaluate outflow pathways from subconjunctival blebs and to identify their identity. Post-mortem porcine (n = 20), human (n = 1), and bovine (n = 1) eyes were acquired, and tracers (fluorescein, indocyanine green, or fixable/fluorescent dextrans) were injected into the subconjunctival space to create raised blebs where outflow pathways were visualized qualitatively and quantitatively. Rodents with fluorescent reporter transgenes were imaged for structural comparison. Concurrent optical coherence tomography (OCT) was obtained to study the structural nature of these pathways. Using fixable/fluorescent dextrans, tracers were trapped to the bleb outflow pathway lumen walls for histological visualization and molecular identification using immunofluorescence against lymphatic and blood vessel markers. Bleb outflow pathways could be observed using all tracers in all species. Quantitative analysis showed that the nasal quadrant had more bleb-related outflow pathways compared to the temporal quadrant (nasal: 1.9±0.3 pathways vs. temporal: 0.7±0.2 pathways; p = 0.003). However, not all blebs resulted in an outflow pathway (0-pathways = 18.2%; 1-pathway = 36.4%; 2-pathways = 38.6%; and 3-pathways = 6.8%). Outflow signal was validated as true luminal pathways using optical coherence tomography and histology. Bicuspid valves were identified in the direction of flow in porcine eyes. Immunofluorescence of labeled pathways demonstrated a lymphatic (Prox-1 and podoplanin) but not a blood vessel (CD31) identity. Therefore, subconjunctival bleb outflow occurs in discrete luminal pathways. They are lymphatic as assessed by structural identification of valves and molecular identification of lymphatic markers. Better understanding of lymphatic outflow may lead to improved eye care for glaucoma surgery and ocular drug delivery.

XEN® Gel Stent: A Comprehensive Review on Its Use as a Treatment Option for Refractory Glaucoma

The XEN Gel Microstent is a subconjunctival microinvasive glaucoma surgical device developed with the aim of improving the predictability and safety profile of bleb-forming glaucoma surgical procedures. The stent is a hydrophilic tube composed of a porcine gel cross-linked with glutaraldehyde with good stability and biocompatibility with minimal tissue reaction. This device has demonstrated promising outcomes with fewer risks compared to traditional surgeries. The aim of the review is to present early studies on different designs of the XEN Gel Stent, to summarize different surgical techniques of implantation and to analyze more comprehensively the results, complications and rates of needling of the commercially available device (Xen 45). The review will address separately special cases (PXG, UVG, ICE, congenital glaucoma) and describe small series and case reports.

Structural imaging of conjunctival filtering blebs in XEN gel implantation and trabeculectomy: a confocal and anterior segment optical coherence tomography study

PURPOSE

To describe and compare the conjunctival filtering bleb features after XEN gel implantation and trabeculectomy using anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM).

METHODS

Fifty-two patients who underwent completely successful trabeculectomy (24 eyes) or completely successful XEN gel implantation (28 eyes) were consecutively enrolled. At the sixth-month follow-up, filtering blebs were analyzed with AS-OCT and IVCM. The main outcomes were the following: (i) bleb-wall epithelium cyst-like structure density and area (BECSD, BSCSA), (ii) bleb-wall sub-epithelium cyst-like structure density and area (BSCSD, BSCSA,), (iii) bleb-wall thickness (BT), (iv) bleb-wall epithelial thickness (BET), (v) bleb-wall reflectivity (BR), and (vi) bleb height (BH), for AS-OCT. Mean microcyst density (MMD) and area (MMA) and stromal meshwork reflectivity (SMR) were the IVCM outcomes.

RESULTS

Six-month intraocular pressure was 11.46 ± 3.09 and 10.06 ± 3.39 mmHg in the XEN gel implantation and trabeculectomy, respectively (p > 0.05). At AS-OCT, XEN gel blebs showed lower BH, BT, BET, BR, (p < 0.001), and BECSA values (p < 0.005), and a higher BECSD (p < 0.05) compared with trabeculectomy blebs. At IVCM, MMA and SMR values were lower in the XEN gel implantation, compared with trabeculectomy (p < 0.05). BECSD and BSCSD negatively correlated with BR (p < 0.01; r = - 0.110; p < 0.01; r = - 0.249), whereas BR strongly correlated with SMR (p < 0.001; r = 0.819).

CONCLUSION

Successful filtering blebs after XEN gel implantation appeared flatter and thinner, with a higher number of epithelial cysts and a hypo-reflective bleb wall compared with trabeculectomy. These aspects may depend on the different intra-operative tissue manipulation and/or on different aqueous humor dynamics in the sub-conjunctiva between surgeries.

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.

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.

Anterior Segment Optical Coherence Tomography: Applications for Clinical Care and Scientific Research

Anterior segment optical coherence tomography (AS-OCT) is a non-contact imaging technique that produces high-resolution images and quantitative measurements of the anterior segment and its anatomical structures. There has been rapid development of OCT technology over the past 2 decades, with the transition from time-domain to Fourier-domain OCT devices. By integrating these advancements in OCT technology, AS-OCT devices have evolved into versatile clinical and research tools for studies of the anterior segment and ocular surface. The primary purpose of this article was to review OCT technology and AS-OCT devices as well as applications of AS-OCT for clinical practice and scientific research. We first describe the different types of OCT technology, how they have been adapted for AS-OCT imaging, and differences between various AS-OCT devices. We then review the applications of AS-OCT for characterizing the anatomical structures of the anterior segment and aqueous outflow pathways, including the anterior chamber angle, trabecular meshwork, and Schlemm canal. We also describe glaucoma-related applications of AS-OCT imaging, which include evaluating patients for static and dynamic biometric risk factors of primary angle closure disease and assessing the efficacy of glaucoma interventions, such as laser peripheral iridotomy and glaucoma surgery. Finally, we review other clinical applications of AS-OCT imaging for detection and management of diseases of the ocular surface, cornea, and lens.

Recommendations for the management of elevated intraocular pressure due to bleb fibrosis after XEN gel stent implantation

Surgical management of glaucoma offers a means of effective disease control. A gel stent that facilitates drainage to the subconjunctival space offers intraocular pressure (IOP) reduction similar to traditional glaucoma filtering surgeries in a less invasive manner. However, like all subconjunctival filtering procedures that result in a bleb, fibrosis can present as a cause of elevated IOP. The following proposed techniques and recommendations for managing elevated IOP due to bleb fibrosis after gel stent implantation are based on the clinical experience of the authors. The goal of this paper is to improve outcomes following gel stent surgery by providing guidance on assessment of bleb function and strategies for bleb enhancement.