XEN 45 Gel Stent Implantation in Open Angle Glaucoma: 5-Year Results of a Prospective Study.

PRCIS: XEN 45 Gel Stent is safe and effective for 3 years. The study results provide useful insight into the outcome of XEN 45 Gel Stent surgery over 5 years in daily clinical practice. PURPOSE: To evaluate 5-year outcomes of XEN 45 gel stent implantation (XEN) in patients with open angle glaucoma. METHODS: This is a prospective, single-center, interventional study. XEN implantation either alone (XEN) or combined with phacoemulsification (Phaco + XEN) was performed on 170 consecutive eyes (126 patients) with uncontrolled intraocular pressure (IOP) or disease progression despite medical treatment. "Complete" surgical success at 60 months was defined as unmedicated IOP ≤15 mm Hg and a relative IOP reduction ≥20% from medicated baseline, while "qualified" success allowed fewer ocular hypotensive medications than at baseline. Other definitions of success with various IOP targets were also analyzed. Secondary outcomes included mean IOP and IOP-lowering medication changes and rates of reoperations. RESULTS: Mean age was 78.1±9.2 years, and 70.3% were female. Mean medicated IOP decreased from 19.8±7.7 mm Hg [19.6±7.1 (XEN) vs. 19.8±7.0 mm Hg (Phaco+XEN)] at baseline to 12.6±3.1 mm Hg [12.5± 3.1 (XEN) vs. 12.6±3.1 (Phaco+XEN)] at 5 years (-37.0%; P < 0.001). Medications decreased from 2.0±1.3 [2.0±1.3 (XEN) vs. 2.0±1.3 (Phaco+XEN)] to 0.8±1.1 [0.8±1.1 (XEN) vs. 0.8±1.1 (Phaco + XEN)] (-60%; P <0.001). Needling was performed in 84 eyes (49%), and 19.4% underwent a secondary surgical intervention. Complete success at 3 years was a strong predictor of success at 5 years (odds ratio: 3.06, P <0.01), while needling was associated with higher rates of failure (odds ratio: 3.6, P <0.01). CONCLUSIONS: At 5 years, XEN gel stent implantation was a safe procedure and achieved clinically meaningful IOP and medication reduction. Success at 3 years is a predictor of success at 5 years. Needling correlates with higher failure rates.

Iridocorneal Angle Assessment After Laser Iridotomy With Swept-source Optical Coherence Tomography.

AIM: To investigate the reliability of anterior chamber angle (ACA) measurements in narrow angles and assess the effect of laser peripheral iridotomy (LPI) on these measurements using novel swept-source optical coherence tomography (SS-OCT) technology. MATERIALS AND METHODS: In this prospective observational study, patients with gonioscopically narrow angles were enrolled and scheduled for prophylactic LPI. Twelve ACA sections were obtained in each eye using SS-OCT (ANTERION, Heidelberg Engineering, Germany) before and after Nd:YAG LPI. A built-in algorithm calculated ACA measurements after manual identification of the scleral spur and ACA recess. Eight ACA parameters were evaluated: ACA (ACA 500, ACA 750); scleral spur angle (SSA 500, SSA 750); angle opening distance (AOD 500, AOD 750); and trabecular iris space area (TISA 500, TISA 750). The effect of LPI was assessed for each parameter, both nasally and temporally. RESULTS: Ten patients (18 eyes) were enrolled (mean age, 61.8±13.6 y; 60.0% female individuals). On average, the ACA was wider nasally than temporally (P=0.004). LPI significantly widened the ACA (range, 26.7-29.4%; P<0.05). ACA 500 increased by 29.4% (P<0.001), ACA 750 by 29.2% (P=0.002), SSA 500 by 27.3% (P=0.003), SSA 750 by 28.1% (P=0.001), AOD 500 by 28.6% (P=0.009), AOD 750 by 28.6% (P=0.003), TISA 500 by 27.3% (P=0.004), and TISA 750 by 26.7% (P=0.200). CONCLUSIONS: SS-OCT ANTERION imaging can be used to reliably measure ACA before and after LPI. ACA, AOD, SSA, and TISA are all valid ACA measurement methods.

A Prospective Analysis of iStent Inject Microstent Implantation: Surgical Outcomes, Endothelial Cell Density, and Device Position at 12 Months.

PRECIS: The surgical outcome of iStent inject devices is associated with device protrusion within the anterior chamber. Schlemm canal (SC) dilatation has a prognostic value. iStent inject devices do not move within the first year after implantation. INTRODUCTION: The iStent inject is a device designed to be implanted ab-interno through the trabecular meshwork. The present study follows up on our preliminary report, using successive in vivo anterior segment optical coherence tomography (AS-OCT) imaging to analyze the associations between stent positioning, iridocorneal angle structures, and surgical outcomes. METHODS: In total, 54 eyes of 42 patients (73.3±7.4 y) with cataract and mild-to-moderate open-angle glaucoma were examined in this prospective study. All patients underwent implantation of 2 iStent inject devices combined with phacoemulsification. Patients were followed up over a 12-month period. AS-OCT was performed after 3 and 12 months. Thirty unoperated fellow eyes served as control eyes. RESULTS: Intraocular pressure (IOP) decreased from 16.5±4.2 mm Hg at baseline to 15.1±3.7 mm Hg at 12 months (-8.7%; P=0.004), while medications decreased from 1.8±1.0 to 0.5±0.9 (-72.2%; P<0.001). Unmedicated IOP≤18 mm Hg was achieved in 58.8% of operated eyes. No sight-threatening complications were reported. On AS-OCT, 44.9% of devices were buried within the trabeculum. Device position was unchanged between scans. Regression analysis elicited significant predictors: SC dilatation effect [risk ratio (RR)=0.230; P=0.003], greatest SC diameter (RR=0.991; P=0.049), extrusion of the most anterior device (RR=0.993; P=0.012), gonioscopically visible devices (RR=0.406; P=0.040), baseline treatments (RR=2.214; P=0.001), and baseline IOP (RR=0.184; P=0.006). Endothelial cell density decreased by 14.6% at 12 months (P<0.001). CONCLUSIONS: This study demonstrates the IOP-lowering and medication-lowering potential of iStent inject surgery in primary open-angle and pseudoexfoliative glaucoma. It confirms that surgical outcomes are positively associated with device protrusion within the anterior chamber, and suggests SC dilatation effect as a favorable prognostic indicator. It shows that stents are stable in time, highlighting the importance of the initial implantation location.

Bilateral XEN Stent Implantation: A Long-term Prospective Study of the Difference in Outcomes Between First-operated and Fellow Eyes.

BACKGROUND/AIMS: Both eyes of a same person are not completely independent entities. The purpose of this study was to assess the difference in outcome between the first-operated eye and the fellow-operated eye following bilateral XEN surgery, and to identify potential success predictors for the fellow eye. METHODS: This single-site, prospective, nonrandomized interventional study investigated bilateral nonsimultaneous XEN gel stent implantation over 24 months. Its main outcome measure was surgical success, defined as unmedicated intraocular pressure (IOP) ≤15 mm Hg associated with a relative reduction ≥20%. RESULTS: Of 149 enrolled eyes, 74 eyes of 37 patients who underwent bilateral (standalone or combined) XEN implantation, within a mean of 50.5±74.3 days of each other, were analyzed. Postoperatively, mean medicated IOP decreased from 19.0±6.6 (first-operated) and 18.2±5.2 mm Hg (fellow) at baseline (P=0.209) to 13.7±4.0 (-27.9%; P<0.001; first-operated) and 14.1±3.6 mm Hg (-22.5%; P<0.001; fellow) after 2 years (P=0.673). Rates of complete success were comparable between first-operated and fellow eyes (P=0.65). At 2 years, among patients whose first-operated eyes were considered a failure, 92.0% of fellow eyes failed (P=0.001). The odd ratio of a fellow eye experiencing complete success were 16.1 (95% confidence interval: 2.5-101.9, P=0.003) if the first operated eye experienced complete success. CONCLUSIONS: The present study demonstrated a strong association between first-operated eyes and fellow eyes following XEN gel stent implantation, in terms of surgical outcomes and IOP reduction. In effect, surgical success in the first-operated eye increases the odds of success in the fellow eye by 16-folds.

Impact of Phacoemulsification Combined with XEN Gel Stent Implantation on Corneal Endothelial Cell Density: 2-Year Results.

INTRODUCTION: Corneal integrity has long been a preoccupation of glaucoma surgeons considering glaucoma drainage device surgery or antimetabolite-enhanced trabeculectomy. Despite having demonstrated a good safety profile and significant intraocular pressure-lowering capacities, the impact of XEN gel stents on endothelial density was never specifically investigated. The purpose of this study is to assess the effect of XEN gel stents on central endothelial cell density (ECD) over 24 months. To achieve this, we compared the effect on ECD of combined XEN surgery with that of a standard phacoemulsification procedure. METHODS: This was an investigator-initiated, retrospective study, conducted at a single tertiary glaucoma center. Patients with primary or secondary open-angle glaucoma who underwent XEN implantation combined with phacoemulsification between January 2015 and June 2016 were retrospectively enrolled. Patients who had undergone standalone phacoemulsification over the same period of time were enrolled to form the control group of this comparative study. The primary outcome measure was the ECD. Patients who had undergone standalone XEN implantation and patients for whom both a baseline and 24-month ECD could not be obtained were excluded from the analysis. Percentages of ECD reductions were calculated for each studied eye, and the mean of ECD reductions was calculated for each group as well as for subgroups. RESULTS: Thirty-two eyes of 23 patients (mean age=76.0±7.9 y, 60% female) underwent standalone phacoemulsification (n=15) or combined XEN surgery (n=17) and had an ECD both at baseline and 24-month postoperatively. Mean baseline ECDs were 2568±491 versus 2379±335 cells/mm, respectively (P=0.21). In the combined XEN surgery group, 58.8% of eyes (n=10) required at least 1 mitomycin C (MMC)-enhanced needling revision to maintain their target intraocular pressure. In the standalone phacoemulsification group, ECD decreased by a mean 14.5%, from 2567.7±491.2 to 2196.1±591.9 cell/mm (P=0.072). In the combined XEN surgery group, ECD decreased by a mean 14.3%, from 2378.8±334.7 to 2039.6±451.1 cell/mm (P=0.018). The difference in percentage reduction of ECD between the 2 groups was not statistically significant (P=0.226). Within the combined XEN surgery group, the ECD decreased by a mean of 15.4% in patients who did not undergo needling revisions and by 13.1% in patients who underwent the MMC-augmented procedure (P=0.485). In the 3 patients who underwent >1 needling revision, a 21.3% reduction in ECD was observed, but the difference was not statistically significant (P=0.653). Neither the time of the first needling (P=0.452), the patients' age (P=0.285), or sex (P=0.308) was statistically associated with ECD loss. DISCUSSION: The present study demonstrated that the XEN gel implant combined with phacoemulsification produces 24-month ECD loss of a similar magnitude to that observed following standalone phacoemulsification. MMC-augmented needling revisions do not appear to have an impact on ECD.

Pericardium Patch Graft (Tutoplast) for Bleb Repair and Bleb Remodelling After Nonpenetrating Filtering Surgery: 6-Month Outcomes.

PURPOSE: The purpose of this study was to evaluate the outcome of pericardium patch graft (Tutoplast) as an adjuvant to either bleb repair or bleb reduction after nonpenetrating filtering surgery. METHODS: Retrospective study, at a tertiary glaucoma center. Bleb revision with Tutoplast positioning was performed either for bleb repair to treat early leaks or hypotony with maculopathy, either for bleb reduction to improve ocular pain, discomfort, burning, foreign body sensation, tearing, and fluctuations of visual acuity. Intraocular pressure (IOP), best corrected visual acuity, number of antiglaucoma medications, and postoperative complications were analyzed postoperatively at 1 week, 1, 3, 6 months, and compared with the preoperative baseline. Surgical success was defined as achieving an IOP between 8 and 16 mm Hg. RESULTS: Six-month data were available from 15 eyes of 15 patients; mean patient age was 69.6±11.7 (66.7% male). Bleb revision was necessary for 10 patients due to bleb dysesthesia (bleb reduction), and in 5 patients due to leaking filtering bleb (bleb repair). The success rate was 73.3% at 6 months, with a significant IOP increase from 4.9±2.2 mm Hg preoperatively to 12.7±3.5 mm Hg at 6 months (P=0.0001), and a concomitant rise of best corrected visual acuity from 0.5±0.3 to 0.6±0.3 (P=0.2871). To control IOP, antiglaucoma medications were needed for 3 patients (20%) at 6 months. Overall, 3 patients (20%) required additional bleb revision for persistent hypotony, and 1 patient underwent a subsequent glaucoma surgery (transscleral cyclodestruction). CONCLUSION: Pericardium patch graft (Tutoplast) is a safe and effective adjuvant for bleb revision due to bleb dysesthesia of leaking filtering bleb after nonpenetrating filtering surgery.

EyeWatch Rescue of Refractory Hypotony After Baerveldt Drainage Device Implantation: Description of a New Technique.

The most effective way to control glaucoma is by lowering intraocular pressure (IOP) in order to prevent the progression of the disease. Glaucoma drainage devices (GDDs) are surgical option reserved for refractory cases and have been designed to address known complications of conventional filtering surgery. They are, however, associated with a higher rate of complications related to early hypotony and late corneal decompensation. In the case of the commonly used Baerveldt Glaucoma Implant (BGI), techniques exist in an attempt to prevent early postoperative hypotony but can be highly variable and surgeon dependent. Moreover, the additional steps required can result in unstable IOP in the immediate postoperative period. In 2014, Villamarin and colleagues described for the first time an adjustable GDD, called the eyeWatch implant, designed to better control IOP fluctuations and avoid hypotony during the early postoperative period via magnetic control of the device tube lumen. This innovation provides the possibility to adjust the amount of aqueous humor outflow after device implantation in a noninvasive manner. We report the case of an 83-year-old patient with advanced pseudoexfoliative glaucoma, referred to our tertiary center because of disease progression despite topical therapy and having undergone deep sclerectomy. First, a BGI was implanted but was unfortunately complicated by a 3-month chronic refractory hypotony from day 8, and choroidal detachment despite medical management, choroidal drainage, and viscoelastic injections. After 3 months, the decision was made to rescue the situation with an eyeWatch adjunction to the BGI. Postoperatively, the IOP was successfully controlled through fine adjustments of the eyeWatch opening position, until the last visit 8 months after the rescue, with complete resolution of the choroidal detachment and without any medications. This demonstrates that the eyeWatch may offer an answer not only to the immediate postoperative hypotonic phase of the GDD surgery but also to the later cystic bleb hypertonic phase.

XEN Gel Stent in Pseudoexfoliative Glaucoma: 2-Year Results of a Prospective Evaluation.

PRéCIS:: This study confirms the safety and efficacy of XEN gel stents in the management of pseudoexfoliative glaucoma 2 years after implantation, with success rates similar to primary open-angle glaucoma regardless of the definition of success. PURPOSE: To compare the long-term safety and efficacy of XEN gel implant surgery (Allergan Inc., Irvine, CA) in patients with pseudoexfoliative glaucoma (PEXG) and primary open-angle glaucoma (POAG). SETTING: Prospective, interventional study in a tertiary glaucoma center. METHODS: A total of 110 eyes of 85 patients with POAG (57 eyes) or PEXG (53 eyes) and uncontrolled intraocular pressure (IOP) despite medical treatment underwent combined XEN+cataract surgery or standalone XEN surgery. Mean IOP, mean number of medications, needling rates, and incidence of adverse effects were compared between the 2 groups. Complete surgical success was defined as an unmedicated IOP≤12, 15, 16, or 18 mm Hg at 2 years, both with and without a 20% reduction from baseline. RESULTS: Combined XEN+cataract surgery was performed in 72% of POAG and 76% of PEXG eyes (P=0.67), the remainder underwent standalone XEN surgery. Patient characteristics were similar between the 2 groups except for older age for the patients with PEXG (78.5±8.5 vs. 71.3±8.7 y; P<0.005). Mean medicated IOP were 19.8±5.8 mm Hg (POAG) versus 19.8±8.2 mm Hg (PEXG) at baseline (P=0.98), and 14.5±3.6 mm Hg (-26.8%) versus 14.2±3.8 mm Hg (-28.3%), respectively, at 2 years (P=0.75). Mean medications concomitantly dropped from 1.9±1.6 (POAG) versus 2.0±1.3 (PEXG) to 0.6±0.9 versus 0.4±0.7, respectively (P=0.29). Using the 16 mm Hg threshold, 51.4% (POAG) versus 57.1% (PEXG) eyes achieved complete success (P=0.70) at 2 years. The difference in success rates between the 2 groups was not statistically significant under any of the definitions of success. By 24 months, needling was performed in 42.8% (POAG) and 43.2% (PEXG) (P=0.64), with an average time to needling of 162.8 and 134.9 days, respectively (P=0.46). The rates of adverse effects were 30.6% (POAG) and 36.4% (PEXG) (P=0.66), and additional glaucoma surgeries were carried out in 14.3% (POAG) versus 15.9% (PEXG) (P=0.89). CONCLUSIONS: The XEN gel implant as a standalone or combined procedure demonstrated similar efficacy and safety results in PEXG and POAG eyes.

A Prospective Analysis of iStent Inject Microstent Positioning: Schlemm Canal Dilatation and Intraocular Pressure Correlations.

PRéCIS:: A larger proportion of iStent inject microstents than suggested by gonioscopic examination could be entirely burrowed within the trabeculum (45.7%). The length of device protrusion within the anterior chamber is linked to postoperative intraocular pressure (IOP). INTRODUCTION: The iStent inject is a relatively new device designed to be implanted ab-interno through the trabecular meshwork. Although some preliminary studies have shown IOP-lowering potential, the full extent of the mechanisms through which IOP is reduced remains unconfirmed. The aim of this study was to use in vivo optical coherence tomography analysis of the anatomic and physiological effects of iStent inject device positioning on the structures of the iridocorneal angle and IOP. METHODS: In total, 25 eyes of 19 subjects (mean age, 75.5±10.5 y) with mild to moderate open-angle glaucoma were enrolled in this prospective study. All patients underwent implantation of 2 iStent inject devices combined with cataract surgery. In the postoperative period, after IOP stabilized, anterior segment optical coherence tomography (AS-OCT) was performed and several measurements were made of the Schlemm canal (SC) and the devices' positions. Thirteen unoperated fellow eyes served as control eyes. RESULTS: Overall, 92% of devices were visible on AS-OCT versus 88% visible on gonioscopic examination. Of all visible devices, 54.3% had a protruding portion into the anterior chamber with a mean protruding length of 88.5 µm, and 72% of the devices' heads were not positioned within the SC, with a mean shortest distance of 109.4 µm. In operated eyes, the average major diameter of SC was 308.7±197.4 µm (median, 303.8 µm) versus 126.9±60.3 µm in control eyes. Device protrusion and larger SC diameters were associated with lower postoperative IOP (rs=-0.54; P=0.005 and rs=-0.43; P=0.04, respectively), whereas the distance between the devices' heads and SC was inversely associated with SC dilatation (rs=-0.41; P=0.04). CONCLUSIONS: This study highlights the value of AS-OCT in exploring the positioning of trabecular bypass devices such as the iStent inject. Our study shows that more microstents than suggested by gonioscopy could be completely burrowed within the trabeculum. It also suggests that the surgical outcomes of cataract surgery combined with iStent inject implantation may be connected to the amplitude of device protrusion within the anterior chamber as well as the postoperative dimensions of the SC.

Anterior Chamber XEN Gel Stent Movements: The Impact on Corneal Endothelial Cell Density.

INTRODUCTION: Although there are several examples of glaucoma drainage devices' dislocations in the literature, the movement of XEN gel stents is scarcely documented, and the impact of such displacements on the corneal endothelium remains unknown. In light of the recent global market withdrawal of the CyPass microstent over concerns with regard to endothelial cell loss, we present a case of XEN gel stent dislocation into the anterior chamber, with localized corneal damage. CASE REPORT: We describe the case of a 64-year-old female patient who underwent bilateral XEN gel stent implantation for normal-tension glaucoma. While right eye surgery was uneventful, intraocular pressure increased in the left eye, and examination revealed a flat filtration bleb with no microstent visible through the conjunctiva. A 3 mm segment of the XEN stent was visible within the anterior chamber, with corneal contact during eye movement and blinking. Endothelial cell density was measured twice 1 month apart before the XEN gel stent was replaced. DISCUSSION: First, our observations confirm that XEN gel stents can dislocate and advance within the anterior chamber. We speculate that this displacement was caused by regular eye rubbing after surgery. Second, this report illustrates that the position of a drainage device within the anterior chamber is dynamic and significantly influenced by eye movements and blinking. Finally, occasional corneal contact of a XEN gel stent can cause a reduction in endothelial cell density of 2.1% in a month, which represents 46.2% of the annual endothelial loss observed by Tan and colleagues in patients with a Baerveldt tube (4.54% annual decrease).

Congenital Refractory Glaucoma: A New Ophthalmic Association of Kabuki Syndrome and its Management With Glaucoma Drainage Devices.

INTRODUCTION: Kabuki syndrome (KS) is a rare congenital and polymalformative condition, traditionally associated with mental retardation, unusual facial features, and skeletal abnormalities. We hereby describe a case of bilateral congenital glaucoma associated with MLL2-mutation KS. To the best of our knowledge, this is the first association of KS with congenital glaucoma. CASE REPORT: The patient was a 3-year-old male of North African ethnicity diagnosed with KS and bilateral congenital glaucoma at the age of 3 months and the first child of a nonconsanguineous healthy couple, with no known genetic conditions within the family. The patient was referred to our tertiary glaucoma center with uncontrollable intraocular pressures between 50 and 60 mm Hg in both eyes. Past ophthalmic history included bilateral trabeculectomies and right retinal detachment with phthisis bulbi. We performed left lensectomy combined with Baerveldt tube insertion in the vitreous cavity, revealing extensive posterior synechiae. Postoperatively, he developed intense inflammation with fibrin and vitreous strand formation, requiring subsequent surgeries and subconjunctival injections of betamethasone. Despite these complications, IOP stabilized between 3 and 6 mm Hg. DISCUSSION: This case confirms congenital glaucoma as a rare association of KS, and highlights the potential high-risk nature of such cases. In our opinion, the presence of high levels of inflammation perioperatively and postoperatively is an indication for primary glaucoma drainage device surgery given the high risk of bleb scarring resulting in recurrent surgical revisions. In view of these observations, we also advocate the use of intensive postoperative anti-inflammatory therapy.

Baerveldt-Baerveldt Apposition: A New Surgical Technique to Salvage Obstructed Glaucoma Drainage Tubes.

AIM: Glaucoma drainage device (GDD) failure is usually rectified by the replacement of the entire device or using a tube extender, both of which were associated with postoperative complications. To minimize these risks, we developed a technique to replace the failing section of a tube while keeping the filtration plate in place, and without resorting to an extender clip. BACKGROUND: We describe the case of a 69-year-old man, whose left posttraumatic glaucoma was initially treated with a XEN-augmented Baerveldt procedure. Following recurrent obstructions, a kinked section of the Baerveldt tube was sectioned and replaced. TECHNIQUE: After sectioning the blocked section of the tube, a new Baerveldt tube was inserted into the anterior chamber. Its filtration plate was removed, and the posterior end of the new tube was connected to the anterior end of the existing device so that both lumens would be continuous. The adjoining tubes were stitched to each other with two 8-0 nylon sutures passing through the walls of the tubes. An allograft patch was replaced over the tubes and the conjunctival fornix was closed. Intraocular pressure (IOP) normalized immediately after surgery and remained stable through 6 months. CONCLUSION: This surgical approach offers a new way to salvage a failing Baerveldt tube without replacing the filtration plate, repeating a complete surgery, or potentially compromising the conjunctiva with an extender. The minimal residual gap at the junction between the tubes appears to provide the same additional IOP-lowering effect as the "venting slits" that are sometimes performed to minimize the initial hypertensive phase without causing hypotony. CLINICAL SIGNIFICANCE: This report illustrates a simple yet effective technique to replace the failing section of a GDD or lengthen a short GDD without replacing the entire device or using an extender clip, and thus minimizing the risks of complications. HOW TO CITE THIS ARTICLE: Gillmann K, Mansouri K, Bravetti GE, et al. Baerveldt-Baerveldt Apposition: A New Surgical Technique to Salvage Obstructed Glaucoma Drainage Tubes. J Curr Glaucoma Pract 2019;13(3):110-112.

Delayed Obstruction of XEN Gel Stent by Cell Debris in Primary Open-angle Glaucoma: A New Insight into the Pathophysiology of Filtration Device Failure.

AIM: The aim of this report is to explore the risk factors of XEN stent obstruction, suggesting the need for a stricter control of these factors and highlighting areas for further research. BACKGROUND: Despite its proven effectiveness and safety profile, XEN gel stents (Allergan Plc, Dublin, Ireland) can become obstructed. The causes and predicting factors for such obstructions still require further research. While hyphema has long been known to be responsible for secondary glaucoma through trabecular obstruction, it has not been associated, to date, with XEN gel stent obstruction. CASE DESCRIPTION: We describe the case of a 55-year-old female patient with primary open-angle glaucoma (POAG) who underwent bilateral XEN gel surgery. Her left eye developed a 2 mm postoperative hyphema, which resolved spontaneously within 8 days. Intraocular pressure (IOP) normalized at 12 mm Hg and increased to 50 mm Hg after 1 month in an otherwise normal-looking eye. Intraoperative examination revealed a nonfunctioning XEN gel stent, which was replaced and sent for laboratory analysis. Macroscopic examination of the tube confirmed obstruction with cellular debris. Tube replacement restored good filtration. CONCLUSION: This case report confirms cellular debris as a potential cause of XEN gel stent occlusion, suggesting that aqueous red blood cells (RBCs) could potentially pose a threat to the microstents' patency even in cases when the bleeding was minimal and self-limited and where the IOP was still controlled at the time of full hyphema resolution. This observation could lead to recommendations for a stricter control of bleeding risk factors prior to microinvasive glaucoma surgery (MIGS), and it raises the question of whether anterior chamber (AC) washout should be advised in postoperative hyphema. CLINICAL SIGNIFICANCE: This case highlights some previously unreported risk factors for XEN stent obstruction and suggests that stricter control of bleeding and monitoring of patients following hyphema could improve surgical outcome. HOW TO CITE THIS ARTICLE: Gillmann K, Bravetti GE, Mansouri K. Delayed Obstruction of XEN Gel Stent by Cell Debris in Primary Open-angle Glaucoma: A New Insight into the Pathophysiology of Filtration Device Failure. J Curr Glaucoma Pract 2019;13(3):113-115.

Chronic Intraocular Inflammation as a Risk Factor for XEN Gel Stent Occlusion: A Case of Microscopic Examination of a Fibrin-obstructed XEN Stent.

INTRODUCTION: In recent years microinvasive glaucoma surgery has risen in popularity. Among microinvasive glaucoma surgery options is the XEN gel stent (Allergan Plc, Dublin, Ireland), a 45 µm wide ab-interno microstent. It has proven effective in lowering intraocular pressure (IOP) with low complication rates. However, XEN gel stents can become obstructed and cause postoperative rise in IOP. The causes and predicting factors for such obstructions still requires further research. CASE REPORT: We describe the case of a 69-year-old male patient, with traumatic glaucoma and chronic intraocular inflammation showed by laser flare photometry, following childhood trauma and anterior segment surgery. Uncontrollable IOP despite maximal antiglaucomatous therapy was managed with XEN-augmented Baerveldt surgery. Despite good initial filtration and IOP control, the XEN stent became obstructed and was surgically replaced. After a month, the new stent became obstructed and was replaced by a thicker-lumened Baerveldt tube. This restored good filtration, and adequate IOP was maintained postoperatively. Microscopic examination of the obstructed XEN stent showed a dense fibrin plug. DISCUSSION AND CONCLUSIONS: This case report shows that fibrin formation could be an important factor in XEN gel stent obstruction, even in initially successfully filtering stents. The association of fibrinogenesis and intraocular inflammation could add a note of caution to the use of XEN gel stents in complicated cataract surgery, or advocate for aggressive anti-inflammatory treatments postoperatively. This could lead to a refinement in success predictors and better patient selection for XEN surgery. Finally, this could open the way to new management options for persistent obstructions, including pharmaceutical fibrinolysis.