A Randomized Controlled Trial Comparing Subconjunctival Injection to Direct Scleral Application of Mitomycin C in Trabeculectomy

Efficacy and safety of intraoperative injection of mitomycin C during trabeculectomy: a systematic review and meta-analysis

PURPOSE

Trabeculectomy, a primary surgical treatment for glaucoma, often employs mitomycin C (MMC) to reduce scar formation and improve surgical outcomes. However, the optimal application method of MMC, whether by injection or sponge, remains a subject of debate. This meta-analysis aims to compare injectable and sponge-based MMC application in terms of efficacy and safety, focusing on various clinical outcomes in glaucoma patients.

METHODS

A comprehensive literature search of Scopus, MEDLINE, EMBASE, Ovid, Chinese biomedical literature database, China National Knowledge Infrastructure, and Cochrane Library was done for eligible studies that report data of glaucoma patients who were administered MMC by injection or sponge application during trabeculectomy. Outcomes of interest included intraocular pressure (IOP) reduction, bleb appearance grading (height, extent, vascularity), use of anti-glaucoma medications, and rates of complete success, qualified success, and failure. Data were reported as weighted mean differences (WMD) or odds ratios (OR) with confidence intervals (CI). The random-effects inverse-variance model with DerSimonian-Laird estimate of tau2 was employed, with continuity correction applied where necessary.

RESULTS

A total of 15 studies with 1276 participants were included. The meta-analysis revealed no significant difference in IOP reduction between patients treated by MMC injection and sponge application (WMD = - 0.434). Significant differences were observed in bleb appearance grading scores for height (WMD = - 0.170) and extent (WMD = 0.174), with substantial heterogeneity. The use of anti-glaucoma medications was significantly lower in the injection group (WMD = - 0.274). However, there were no significant differences in the rates of complete success, qualified success, and failure. The study demonstrated moderate to high heterogeneity across various outcomes.

CONCLUSION

This meta-analysis indicated that while both injection and sponge methods of MMC application during trabeculectomy were equally effective for IOP reduction, they differ in their impact on bleb morphology and postoperative medication requirement. The findings highlight the need for individualized treatment approaches in glaucoma surgery, taking into account the specific needs and characteristics of each patient.

Failed Ahmed glaucoma valves: trabeculectomy versus repeat shunt surgery

INTRODUCTION

To investigate the outcomes of trabeculectomy (TRAB) versus repeat Ahmed glaucoma valve (re-AGV) implantation in eyes with Ahmed glaucoma valve (AGV) failure.

METHODS

This quasi-experimental study includes patients with failed AGV implants requiring additional surgical intervention between 2018 and 2022. Patients in the TRAB group underwent a fornix-based procedure with mitomycin C 0.01% injection (0.1 mL). Eyes in the re-AGV group underwent repeat shunt surgery. The choice of the procedure was based on conjunctival condition. The primary outcome measure was surgical success rate based on various intraocular pressure (IOP) targets and percentages of IOP reduction from baseline: IOP ≤ 21 mmHg and 20% reduction (conventional criteria), IOP ≤ 18 and > 20% reduction (criterion A), IOP ≤ 15 and > 25% reduction (criterion B), and IOP ≤ 12 and > 30% reduction (criterion C).

RESULTS

Forty-eight eyes of 48 patients were operated and reported herein, consisting of 22 eyes of 22 patients undergoing TRAB and 26 eyes of 26 subjects undergoing re-AGV. No significant difference was observed between the study groups in terms of initial diagnoses, baseline IOP or the number of prior surgeries. The cumulative probability of survival at one year was significantly higher in the trabeculectomy group using the three stricter success definitions. In both study groups, IOP was significantly reduced from baseline at all postoperative visits, and was significantly lower in the TRAB group at all time points beyond one month. At 12 months, 5% of TRAB versus 48% of re-AGV eyes required glaucoma medications (P < 0.001). The rate of complications was comparable between the study groups (P = 0.76) but there was a trend toward a greater need for repeat surgery in the re-AGV group (4 eyes versus nil, P = 0.07).

CONCLUSIONS

Trabeculectomy can be considered a safe and effective surgical option in eyes with failed AGV leading to significantly lower IOP levels and more favorable success rates than re-AGV in selected patients.

Hypotony Failure Criteria in Glaucoma Surgical Studies and Their Influence on Surgery Success

PURPOSE

Review hypotony failure criteria used in glaucoma surgical outcome studies and evaluate their impact on success rates.

DESIGN

Systematic literature review and application of hypotony failure criteria to 2 retrospective cohorts.

PARTICIPANTS

A total of 934 eyes and 1765 eyes undergoing trabeculectomy and deep sclerectomy (DS) with a median follow-up of 41.4 and 45.4 months, respectively.

METHODS

Literature-based hypotony failure criteria were applied to patient cohorts. Intraocular pressure (IOP)-related success was defined as follows: (A) IOP ≤ 21 mmHg with ≥ 20% IOP reduction; (B) IOP ≤ 18 mmHg with ≥ 20% reduction; (C) IOP ≤ 15 mmHg with ≥ 25% reduction; and (D) IOP ≤ 12 mmHg with ≥ 30% reduction. Failure was defined as IOP exceeding these criteria in 2 consecutive visits > 3 months after surgery, loss of light perception, additional IOP-lowering surgery, or hypotony. Cox regression estimated failure risk for different hypotony criteria, using no hypotony as a reference. Analyses were conducted for each criterion and hypotony type (i.e., numerical [IOP threshold], clinical [clinical manifestations], and mixed [combination of numerical or clinical criteria]).

MAIN OUTCOME MEASURES

Hazard ratio (HR) for failure risk.

RESULTS

Of 2503 studies found, 278 were eligible, with 99 studies (35.6%) lacking hypotony failure criteria. Numerical hypotony was predominant (157 studies [56.5%]). Few studies used clinical hypotony (3 isolated [1.1%]; 19 combined with low IOP [6.8%]). Forty-nine different criteria were found, with IOP < 6 mmHg, IOP < 6 mmHg on ≥ 2 consecutive visits after 3 months, and IOP < 5 mmHg being the most common (41 [14.7%], 38 [13.7%], and 13 [4.7%] studies, respectively). In both cohorts, numerical hypotony posed the highest risk of failure (HR, 1.51-1.21 for criteria A to D; P < 0.001), followed by mixed hypotony (HR, 1.41-1.20 for criteria A to D; P < 0.001), and clinical hypotony (HR, 1.12-1.04; P < 0.001). Failure risk varied greatly with various hypotony definitions, with the HR ranging from 1.02 to 10.79 for trabeculectomy and 1.00 to 8.36 for DS.

CONCLUSIONS

Hypotony failure criteria are highly heterogenous in the glaucoma literature, with few studies focusing on clinical manifestations. Numerical hypotony yields higher failure rates than clinical hypotony and can underestimate glaucoma surgery success rates. Standardizing failure criteria with an emphasis on clinically relevant hypotony manifestations is needed.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Short-term outcomes of Mitomycin-C augmented phaco-trabeculectomy using subconjunctival injections versus soaked sponges: a randomized controlled trial

OBJECTIVES

To determine whether subconjunctival Mitomycin-C (MMC) injections are as safe and effective as sponge-soaked MMC in phaco-trabeculectomy.

METHODS

This prospective, randomized, interventional study was conducted on consecutive patients with visually significant cataract and an uncontrolled primary open-angle glaucoma. One hundred thirty-nine patients were recruited but 15 were ineligible for analysis. The patients were randomized into a sponge/injection group. All participants received a twin-site phaco-trabeculectomy. They were followed up on days 1, 15, 30, 3 months and 6 months post-operatively. A p-value < 0.05 was considered significant.

INTERVENTIONS

Participants in the sponge group received an augmentation of their phaco-trabeculectomy with sponges soaked in a mixture of 0.04% MMC and 2% preservative-free Lignocaine in a 1:1 ratio, placed in the subconjunctival space for four minutes. Participants in the injection group received the same mixture as a subconjunctival injection, after surgical draping.

RESULTS

There were 62 patients in each group. The groups had no significant differences in their baseline characteristics. The mean IOP at 6 months was significantly lower in the injection group (14.8 ± 3.7 mm Hg) than in the sponge group (17.1 ± 6.4 mm Hg) (p = 0.02). There was no notable difference in the complications or the final post-operative visual outcome but a significantly greater number of patients in the sponge arm required removal of the releasable suture (p = 0.001) and additional anti-glaucoma medications (p = 0.04) at six months post-operatively.

CONCLUSIONS

Subconjunctival MMC achieves a lower IOP with fewer anti-glaucoma medications than sponge-soaked MMC at six months for twin-site phaco-trabeculectomy in primary open-angle glaucoma with no additional risks.

Comparison of the safety and efficacy of Mitomycin C 0.02% used intra-operatively by subconjunctival injection versus direct scleral application using sponges in phacotrabeculectomy: A prospective randomized controlled trial

PURPOSE

To compare the safety and efficacy of subconjunctival injection (MMC: 0.02%) to those with subconjunctival application of sponges soaked in Mitomycin C (MMC: 0.02%) intra-operatively in patients who underwent phacotrabeculectomy.

METHODS

A total of 68 patients undergoing phacotrabeculectomy were randomized into two groups; the sponge group received 0.02% MMC-soaked sponges (n = 38), and the injection group received subconjunctival injection of 0.02% MMC (n = 30). The primary outcome was post-operative mean intra-ocular pressure reduction (IOP). The secondary outcomes were bleb morphology using Indiana Bleb Appearance Grading Score (IBAGS) and anterior segment optical coherence tomography (AS-OCT), post-operative use of 5-fluorouracil, and complications rates. These were compared at 1 week and 1, 3, and 6 months post-operatively. Complete success was defined as ≥30% reduction in IOP without anti-glaucoma medications.

RESULTS

In sponge and injection groups, the mean pre-operative IOP was 29.1 ± 8.1 and 29.8 ± 8.8 mmHg, respectively. At 6 months, IOP in sponge and injection groups reduced by 52% (14 ± 3.6 mmHg, P < 0.001) and 50% (15.2 ± 4.1 mmHg, P < 0.001), respectively. Complete success was observed in 90.9% in the sponge group and 95.83% in the injection group. Both groups had diffuse, shallow, relatively avascular blebs at 6 months using IBAGS and AS-OCT. A few complications were seen in the sponge group during this period, which were not vision-threatening.

CONCLUSION

Subconjunctival MMC injection is an effective, safe, convenient, and time-saving alternative to sponge-soaked delivery of MMC in phacotrabeculectomy.

Two-year outcomes of anterior versus posterior scleral application of mitomycin C-soaked sponge in trabeculectomy

PURPOSE

To compare the safety and efficacy of two different application methods of mitomycin C (MMC)-soaked sponge in trabeculectomy.

STUDY DESIGN

Retrospective study.

METHODS

We included 71 eyes of 71 patients that had undergone trabeculectomy. In the anterior scleral application group, 36 eyes were treated using the long side of the MMC-soaked sponge placed parallel to the limbus. The efficacy and safety in these eyes were compared with eyes treated with the posterior scleral application group, consisting of 35 eyes treated with the long side of the MMC-soaked sponge placed perpendicular to the limbus. The follow-up period was 2 years. The safety of the procedure, including bleb morphology and complications, was the primary outcome, while the success rate was the secondary outcome.

RESULTS

The cumulative success rate at 2 years postoperatively was 94.4% in the anterior and and 94.3% in the posterior scleral application group (P = 1.000). However, with the posterior scleral application of the MMC-soaked sponge, blebs were more low-lying (P = 0.048), less in extent (P < 0.001), more normally vascularized (P = 0.027) and more posteriorly directed (P < 0.001). Furthermore, the incidence of thin-walled cystic bleb (P = 0.028) and bleb leakage (P = 0.025) was significantly lower in the posterior scleral application group than in the anterior group.

CONCLUSION

Although there were similar success rates, the posterior scleral application of MMC-soaked sponge with trabeculectomy was safer with a better bleb morphology than the anterior scleral application.

Glaucoma Drainage Device Implantation, Outcomes, and Complications

Glaucoma drainage device (GDD) surgery has gained popularity as a treatment strategy for patients with medically uncontrolled glaucoma. Glaucoma is the leading cause of irreversible blindness in the world and continues to be a major public health issue. While our understanding of glaucoma continues to evolve, the primary treatment for glaucoma continues to be intraocular pressure (IOP) control. When medical treatment fails, glaucoma surgery is considered. GDD implantation is one of the most commonly performed incisional glaucoma surgeries. GDD was originally designed for patients with secondary glaucoma and/or patients who are at an increased risk of failure after trabeculectomy. More recently, its application has been extended to primary glaucoma as the first choice of incisional surgery. This manuscript summarizes recent GDD types, implantation, clinical outcome and complications.

Two-stage intra-tenon injection versus sponge-applied mitomycin C-augmented trabeculectomy: a one-year study

PURPOSE

Mitomycin C (MMC) is normally used to avoid scar formation in trabeculectomy. There has been a shift from conventional delivery via soaked sponges to preoperative injection of MMC. This study aimed to compare the effectiveness of a modified two-stage low-dose intra-Tenon injection with soaked sponges of MMC for trabeculectomy over a 1-year follow-up period.

METHODS

This retrospective study enrolled patients with glaucoma undergoing modified trabeculectomy with a two-stage intra-Tenon injection (0.01%, 0.1 mL) or soaked sponges (0.02%) of MMC. In the former group, patients received intra-Tenon injection of MMC (the first stage) at least 4 h before trabeculectomy (the second stage). Patient characteristics, preoperative and postoperative intraocular pressure, antiglaucoma medication use, complications, and post-trabeculectomy surgical interventions were recorded during a 1-year follow-up period.

RESULTS

There were 36 and 35 eyes in the injection and sponge groups, respectively, in 58 patients. The injection group showed significantly lower intraocular pressure (p < 0.05) at every time point except on postoperative day 1 and week 1, fewer medications at the 1-year follow-up (p = 0.018), and a higher complete success rate (p = 0.011) than the sponge group. Both techniques showed a significant reduction in intraocular pressure and medication use at the 1-year follow-up. There were no significant differences in complications between both groups.

CONCLUSION

Our two-stage intra-Tenon MMC injection technique resulted in lower postoperative intraocular pressure, less antiglaucoma medication use, and fewer needling revisions compared to the sponge technique.

Posterior scleral application of a mitomycin C-soaked sponge during trabeculectomy

AIM

To evaluate the safety and efficacy of posterior scleral application (a modified technique) of an antimetabolite mitomycin C-soaked sponge in trabeculectomy for patients with glaucoma.

METHODS

This retrospective study included 101 patients (115 eyes) with glaucoma (aged 12-83y) who underwent trabeculectomy using a modified mitomycin C-soaked sponge placement method. A piece of 3.5×10 mm2 sponge was placed vertically and posteriorly with the long side perpendicular to the limbus. The mitomycin C concentration and exposure time were 0.2-0.5 mg/mL and 1-5min, respectively. Intraocular pressure, best-corrected visual acuity, and hypotensive medications were recorded at baseline and at the final visit. Complications, interventions required, and bleb morphology were recorded postoperatively. The primary outcome was trabeculectomy safety, including complications and bleb morphology; the secondary outcome was the trabeculectomy success rate.

RESULTS

At the final follow-up [median 28mo, range 7-67mo and interquartile range (IQR) 13mo], the qualified (cumulative) success rate was 93.0% and the complete success rate was 60.0%. No bleb-related complications were observed. The mean height, extent, and vascularity grades were 0.6±0.9, 1.1±0.4, and 2.4±0.9, respectively. All Seidel tests were negative. The mean posteriority grade was 0.8±0.4.

CONCLUSION

Trabeculectomy with the long side of a mitomycin C-soaked sponge placed perpendicular to the corneal limbus is safe and effective.

Subconjunctival filtration in evolution: current evidence on MicroShunt implantation for treating patients with glaucoma

BACKGROUND

Although traditional surgical procedures for glaucoma (such as trabeculectomy and tube-shunt implantation) can significantly reduce intraocular pressure (IOP), they are associated with numerous complications, some of which are vision-threatening, or involve prolonged recovery or a highly intensive postoperative course. Micro-invasive glaucoma surgery (MIGS) procedures have shown better safety but reduced efficacy in achieving target IOP. Combinations of these methods have led to the development of subconjunctival micro-invasive procedures with safety comparable to traditional surgery and greater efficacy than minimally invasive methods. This review describes the use of one of these devices, the poly(styrene-block-isobutylene-block-styrene) (SIBS)-based PreserFlo MicroShunt (Santen, Emeryville, CA), in the surgical treatment of patients with glaucoma.

MAIN TEXT

The MicroShunt is an 8.5-mm tube made of an inert polymer with no endplate, an internal diameter of 70 μm, and fins intended to prevent peritubular flow and anchor the device within the sclera to prevent proximal migration into the eye. Following ab externo implantation, the tube provides a conduit for flow of aqueous humor from the anterior chamber into the subconjunctival/sub-Tenon space. Clinical trials to date have shown that, when paired with mitomycin C (MMC) treatment, MicroShunt implantation significantly reduced both IOP and the number of glaucoma medications. These IOP-lowering results were found both when surgery was performed alone and with phacoemulsification. The MicroShunt also showed a safety profile comparable to that of traditional filtering surgery.

CONCLUSIONS

The MicroShunt and other novel subconjunctival procedures have shown substantial IOP reductions while mitigating hypotony-related complications. MMC, which modulates fibrosis and scarring postoperatively, is essential to surgical success. Randomized, long-term clinical trials will further clarify the role of controlled micro-incisional device-assisted ab externo glaucoma filtering surgery in long-term glaucoma management.

Comparative evaluation of outcomes of novel approach of subconjunctival Mitomycin C (MMC) injection at the end of trabeculectomy versus intraTenon injection of MMC prior to the initial conjunctival incision - A pilot study

Purpose

To describe a novel approach of subconjunctival injection of mitomycin C (MMC) at the end of trabeculectomy and compare it with intraTenon MMC injection.

Methods

This pilot study included 40 eyes of 40 patients with uncontrolled primary and secondary glaucoma. Patients below18 years and failed trabeculectomy were excluded. Patients were randomly allocated into groups A and B (20 patients each). Group A patients received subconjunctival MMC injection in the superonasal quadrant at the end of standard trabeculectomy. Group B received an intraTenon MMC injection before the initial conjunctival incision. Outcome measures included intra-ocular pressure (IOP) reduction, bleb morphology, and complication rates. The complete success was defined as an IOP of ≤21 mmHg without antiglaucoma drugs.

Results

The mean preoperative IOP of 46.00 ± 11.2 mmHg in group A and 43.05 ± 10.3 mmHg in group B reduced to 12.00 ± 2.41 mmHg (P ≤ 0.001) in group A and 13.65 ± 2.76 mmHg in group B (P ≤ 0.001) at last follow-up. Complete success was 95% and 75% in groups A and B, respectively, 19 months after surgery. Avascular microcystic blebs (70% of group A and 45% of group B) were more common than avascular white blebs (15% in group A and 35% in group B). No intraoperative complications were seen. Postoperative wound leak, hypotony, choroidal detachment, or endophthalmitis were not encountered in any group.

Conclusion

A novel approach of subconjunctival MMC application during trabeculectomy is reported. Both approaches appear to be highly effective in reducing IOP in primary and secondary glaucoma with similar safety profiles and bleb morphology. Subconjunctival MMC yielded a greater success rate (95%) compared to the intraTenon MMC group (75%).

Combination of Trabeculectomy and Primary Pars Plana Vitrectomy in the Successful Treatment of Angle-Closure Glaucoma with BEST1 Mutations: Self-Controlled Case Series

INTRODUCTION

This study aimed to illustrate the efficacy of the combination of lens extraction, trabeculectomy, and anterior vitrectomy in patients with secondary angle-closure glaucoma (ACG) with autosomal recessive bestrophinopathy or Best vitelliform macular dystrophy.

METHODS

This is a retrospective self-controlled case series study. Five patients undergoing a single trabeculectomy in one eye and triple surgery in the other eye were enrolled. All patients underwent a complete ophthalmic examination that included best-corrected visual acuity (BCVA), intraocular pressure (IOP), ultrasound biomicroscopy, and static gonioscopy. Multimodal fundus imaging was performed, including color fundus photography, fundus autofluorescence, and optical coherence tomography. Genetic testing was also analyzed.

RESULTS

 Among the 10 eyes, the mean IOP was 31.4 ± 4.7 mmHg before surgery. The mean axial length (AL) was 21.53 mm and the anterior chamber depth (ACD) was 2.31 mm. There were no statistically significant differences in preoperative IOP, BCVA, ACD, and AL between the two groups (all P > 0.05). The mean follow-up time was 64.0 months. All five eyes with a single trabeculectomy developed malignant glaucoma (MG). No complications were found in the other five eyes with triple surgery, and the anterior chamber was deepened and stable after surgery until the last visit. The mean IOP at the last visit was normalized to 16 mmHg without using any medications.

CONCLUSIONS

 Triple surgery is superior to single trabeculectomy for patients with ACG and BEST1 mutation, effectively bypassing MG complications. The vitreous may play a vital role in the mechanism of ACG in those patients and the high incidence of MG after filtering surgery.

Surgical Advancement of Tenon's Layer During Trabeculectomy Improves Bleb Morphology

Trabeculectomy surgery remains the gold standard incisional glaucoma surgical procedure in many practices, particularly for patients requiring intraocular pressure (IOP) in the low teens or below. However, trabeculectomy surgery is associated with complications including leakage, over filtration, or fibrosis of the surgical bleb. Morphology of the surgical bleb is an important predictor of surgical success defined as long-term IOP reduction with minimal to no complications. There have been many, often subtle, variations in the surgical technique in hopes of improving long-term IOP reduction. However, fewer changes have been implemented specifically to modify bleb morphology. In our surgical practice, we began performing a thorough dissection and advancement of Tenon's layer with incorporation into the conjunctival closure in a 2-layered manner. This technique allowed flow of aqueous to a delineated potential space between sclera and Tenon's layer. Our clinical observations were improved bleb morphology characterized by diffuse, low-lying blebs with nonischemic overlying conjunctiva compared with those performed with a more traditional trabeculectomy technique. Since we incorporated this change into our practice at a defined time, we have a small number of patients in our practice that had a more traditional trabeculectomy technique in the fellow eye. Therefore, in our surgical practice, a small number of patients had trabeculectomy in 1 eye before implementation of this new technique, and then had trabeculectomy in the fellow eye after this technique was adopted, providing opportunity for comparison of bleb morphology with and without Tenon advancement. In series we present two representative, index cases and describe our surgical technique.

The surgical management of glaucoma: A review

After a long period of little change, glaucoma surgery has experienced a dramatic rise in the number of possible procedures in the last two decades. Glaucoma filtering surgeries with mitomycin C and glaucoma drainage devices remain the standard of surgical care. Other newer surgeries, some of which are minimally or microinvasive glaucoma surgeries, target existing trabecular outflow, enhance suprachoroidal outflow, create subconjunctival blebs, or reduce aqueous production. Some require the implantation of a device such as the iStent, Hydrus, Ex-PRESS, XEN and PRESERFLO, whilst others do not-Trabectome, Kahook dual blade, Ab interno canaloplasty, gonioscopy-assisted transluminal trabeculotomy, OMNI and excimer laser trabeculotomy. Others are a less destructive variation of an established procedure, such as micropulse transscleral cyclophotocoagulation, endoscopic cyclophotocoagulation and ultrasound cycloplasty. Cataract surgery alone can be a significant glaucoma operation. These older and newer glaucoma surgeries, their mechanism of action, efficacy and complications are the subject of this review.

Lipid Nanoparticles for the Posterior Eye Segment

This review highlights the application of lipid nanoparticles (Solid Lipid Nanoparticles, Nanostructured Lipid Carriers, or Lipid Drug Conjugates) as effective drug carriers for pathologies affecting the posterior ocular segment. Eye anatomy and the most relevant diseases affecting the posterior segment will be summarized. Moreover, preparation methods and different types and subtypes of lipid nanoparticles will also be reviewed. Lipid nanoparticles used as carriers to deliver drugs to the posterior eye segment as well as their administration routes, pharmaceutical forms and ocular distribution will be discussed emphasizing the different targeting strategies most recently employed for ocular drug delivery.

A Modified Technique in Applying Sponge Soaked with Mitomycin C in Trabeculectomy

ABSTRACT

Trabeculectomy with adjunctive use of Mitomycin C (MMC) has been a benchmark for glaucoma filtration surgery for decades. However, there are many variations in the ways that the sponges soaked with MMC are applied during the trabeculectomy surgery. We herein describe our way of placing the MMC-soaked sponges to improve the safety and efficacy of the trabeculectomy. The sponges are placed vertically and posteriorly with the long side of the sponge perpendicular to the limbus, not parallel. This will reduce the size of the conjunctival wound at the limbus to preserve more virgin conjunctiva that can be used for repeated trabeculectomy when needed. This will also facilitate a more posteriorly directed flow of aqueous drainage that, in turn, may increase the success rate of the trabeculectomy. We have obtained encouraging results in our practice, and further large-scale randomized studies seem warranted.

Comparison of Safety and Efficacy Between Ab Interno and Ab Externo Approaches to XEN Gel Stent Placement

Purpose

To compare the safety and efficacy of two different techniques for implantation of the XEN Gel Stent, a minimally invasive surgical device for the treatment of refractory glaucoma.

Methods

A retrospective chart review of eyes that received ab interno or ab externo XEN Gel Stent placement from February 2017 to October 2019 was conducted. A single surgeon (NMR) performed all operations. Eyes that received the XEN implant concomitant with a glaucoma drainage device insertion or that were lost to 6-month follow-up were excluded. Intraocular pressure (IOP) change, change in glaucoma medications, frequency of slit lamp revision procedures, and frequency of secondary glaucoma surgeries were the primary outcomes compared between groups.

Results

Fifty eyes that underwent ab interno placement and 30 eyes that underwent ab externo placement were studied. The ab interno cohort demonstrated a mean IOP reduction of 8.4 ± 1.7 mmHg (28.6% decrease) by 12 months, compared to a mean reduction of 12.8 ± 3.0 mmHg (40.1% decrease) in the ab externo group (p = 0.208). Mean reduction in medication use was 1.81 ± 0.29 medications in the ab interno group and 1.86 ± 0.37 in the ab externo group (p = 0.913). By 12 months, 58% of ab interno eyes had required 5-fluorouracil injection compared to 36.7% of ab externos (p = 0.105). Bleb needling was applied to 42% and 26.7% of the eyes, respectively (p = 0.231). A second glaucoma surgery was necessary for 20% of the ab interno cohort and 10% of the ab externo cohort (p = 0.351).

Conclusion

There were no differences in outcomes between ab interno and ab externo placement of the XEN Gel Stent. Both approaches are safe and effective for lowering IOP.