Glaucoma is a leading cause of blindness worldwide. Intraocular pressure (IOP) lowering is the only effective treatment strategy. Traditional glaucoma surgeries are generally considered to be unpredictable and associated with a high rate of complications. This has led to the development of a novel XEN Gel Implant, a type of minimally invasive glaucoma surgery (MIGS), lowering the IOP without extensive surgical dissection. Areas covered: A literature search was undertaken on PubMed using the terms XEN glaucoma, gelatin microstent, and MIGS. All the articles and case reports on XEN Gel Implant and selected articles on MIGS were studied and reviewed. We have discussed the results of most studies on XEN Gel Implant related to its efficacy, safety and success. Expert commentary: The XEN Gel Implant effectively lowers IOP and medication use, with a favorable safety profile. Long-term data on its success and cost-effectiveness are lacking. The studies have shown it to be without any serious adverse events and to have good safety profile encouraging future research on this novel implant. There is a need to correctly identify selection criteria for patients, who would benefit the most from the XEN Gel Implant.
Goniotomy with trabecular meshwork excision using the KDB could be an alternative surgery for severe or refractory glaucoma, significantly reducing IOP and medication use at 6 months, with a low rate of complications.
Introduction: The XEN gel stent is currently the only minimally invasive glaucoma surgical device that targets the subconjunctival outflow pathway through an ab interno placement. It has demonstrated a significant intraocular pressure (IOP)–lowering potential and a favorable safety profile compared with traditional filtering surgery. However, despite a less invasive approach, the presence of a filtering bleb inevitably implies some risk of complications. The most commonly reported bleb-related complication, with rates as high as 45%, is bleb fibrosis associated with raised IOP. To restore filtration in those failing blebs, needling revision is considered the procedure of choice. In this study, we present the results of mitomycin C–augmented needling after XEN implantation. Methods: This was a prospective, interventional study, conducted at a single tertiary glaucoma center. Fifty-one eyes of 51 patients with raised IOP associated with either a fibrotic or shallow bleb or increased vascularity following XEN gel stent implantation at the investigation site between January 2015 and June 2016 were enrolled in this study. Patients with other identified causes of filtration failure (stent malposition, internal ostium obstruction, retained viscoelastic) were excluded. Included patients who underwent mitomycin C–augmented needling revision, and follow-up examinations were conducted at 1 day, 1 week, and 1, 3, 6, 12, 18, and 24 months. The primary outcome was the magnitude of IOP reduction following needling revision at the last follow-up visit. Secondary outcome measures were the number of needling procedures carried out in all patients, the rate of patients requiring further filtering surgery following needling revision, and the rate of intraoperative and postoperative complications associated with needling revisions. Results: The average age was 74.4±9.6 years; 66.7% (n=34) were female individuals. Primary open-angle glaucoma was the most common diagnosis (n=21, 41.2%). A total of 78 needling procedures were performed over the 24-month follow-up. Overall 20 of 51 eyes (39.2%) required >1 needling revision, and 14 eyes (24.5%) eventually required reoperation to maintain IOP within their desired target range. Before XEN implantation, mean preoperative IOP was 22.3±8.2 mm Hg and decreased to 14.1±8.0 mm Hg at day 1 postoperatively (−36.8%). The last measured IOP before the first needling revision was on average 23.6±8.9 mm Hg, which reduced to a mean 12.1±4.2 mm Hg at the first postrevision appointment (−48.7%). At the last follow-up appointment, on average 17.0±7.0 months after the first needling, the mean IOP was 14.3±4.1 mm Hg (−35.9% and −39.4% from preoperative and prerevision baselines, respectively). Complications associated with needling revisions were partial amputation of the XEN implant during needling (n=2, 3.9%), hypotony with choroidal detachment (n=1, 2%), and failure to achieve target IOP requiring subsequent surgery (n=14, 27.5%). No association was found between any of the recorded characteristics and the number of needling revisions performed or their outcomes. Discussion: The present study shows that needling revision following XEN gel stent implantation is a relatively safe and efficient intervention to restore filtration in failing blebs, with a significant and durable IOP-reduction potential.
Purpose: The purpose of this study was to determine the repeatability and reproducibility of a new Pattern Electroretinography (PERG) device in healthy subjects. Methods: A total of 40 eyes of 20 healthy subjects (45.6±6.8 y, 70% female) were enrolled in this prospective study. Steady-state PERG were recorded using the Diopsys NOVA (Diopsys Inc., NJ) to obtain the Magnitude, MagnitudeD, MagnitudeD/Magnitude Ratio, and Signal to Noise Ratio. Subjects underwent 2 “contrast sensitivity” protocols with the same electrodes and 2 after changing electrodes, by a single examiner. Eyes were stimulated separately using high and low contrast patterns. The same examination was repeated by a different operator following the same protocol 6 months after the baseline measures. Repeatability and reproducibility of the readings were calculated using intraclass correlation coefficient (ICC). A Bland-Altman plot was used to analyze the agreement between measures. Results: ICC of Magnitude, MagnitudeD, MagnitudeD/Magnitude ratio, and SNR were 0.87, 0.81, 0.36, and 0.81, respectively between measures taken with the same electrodes (repeatability). After changing electrodes, ICC of the Magnitude, MagD, MagD/Mag ratio, and SNR were 0.79, 0.85, 0.51, and 0.83, respectively during the same session as baseline measures, and 0.87, 0.85, 0.40, and 0.76 when repeated after 6 months (reproducibility). The variability of MagD/Mag ratio increased with successive test repetitions. Conclusions: Mag, MagD, and SNR were repeatable and reproducible, whereas the MagD/Mag ratio was less repeatable and reproducible. These results suggest that the former parameters are sufficiently reliable to be used in clinical practice.
Minimally invasive glaucoma surgery includes different devices which provide a less invasive and safer means of reducing intraocular pressure. The XEN Gel Stent (Allergan Inc., CA) is an ab interno procedure which creates a subconjunctival drainage pathway. It is a new surgical device and there is a paucity of data on complications and their management. We report a clinical case of a leaking bleb after XEN surgery managed by bleb revision, conjunctival suturing, and XEN replacement.
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