XEN Gel Stent in Pediatric Glaucoma

Transconjunctival XEN45 implantation for secondary open-angle glaucoma management in a pediatric patient with WAGR syndrome

Purpose

To report a case of XEN45 gel stent implantation in a pediatric patient with WAGR syndrome as a successful surgical intervention in the management of multifactorial secondary open-angle glaucoma.

Observations

A 6-year-old female with a history of WAGR syndrome, bilateral congenital aniridia, pseudophakia OD and glaucoma OD, was referred for a XEN45 gel stent OD. IOP was persistently elevated at 24 mm Hg despite two glaucoma medications. Implantation of the XEN45 gel stent was performed using a transconjunctival ab externo approach. There were no significant intra-or-postoperative adverse events associated with the stent. The patient achieved good IOP-lowering control without glaucoma medications across the 18-month follow-up period.

Conclusions

A XEN45 stent through a transconjunctival ab externo approach may be an effective surgical intervention in pediatric patients with secondary open-angle glaucoma associated with aniridia and aphakia.

Controversies in Pediatric Angle Surgery and Secondary Surgical Treatment

Pediatric glaucoma is a constellation of challenging ophthalmic conditions that, left untreated, can result in irreversible vision loss. The mainstay of treatment for primary congenital glaucoma and select secondary glaucoma subtypes is angle surgery, either trabeculotomy or goniotomy. More recently, MIGS devices have been utilized to enhance the efficacy of these procedures. Despite the high success rates of these primary surgical options, refractory cases are challenging to manage. There is no consensus on the next step of treatment following primary angle surgery. Glaucoma drainage devices and trabeculectomies have been the traditional options, with laser treatment reserved for more severe cases. The benefits and disadvantages of each of these options are discussed.

A Comprehensive Review of Pediatric Glaucoma Following Cataract Surgery and Progress in Treatment

Glaucoma following cataract surgery (GFCS) remains a serious postoperative complication of pediatric cataract surgery. Various risk factors, including age at lensectomy, intraocular lens implantation, posterior capsule status, associated ocular/systemic anomaly, additional intraocular surgery, and a family history of congenital cataract and GFCS, have been reported. However, the optimal surgical approach remains unclear. This review evaluates the diagnostic criteria, classification, risk factors, mechanism, and surgical management, especially the efficacy of minimally invasive glaucoma surgery, in GFCS, and aims to propose an optimal clinical management strategy for GFCS. The results of our review indicate that ab interno trabeculotomy (goniotomy) may be the most appropriate first-line treatment for GFCS.

Use of a Novel Microshunt in Refractory Childhood Glaucoma: Initial Experience in a Compassionate Use/Early Access Cohort

PURPOSE

In patients with refractory childhood glaucoma, treatment options include trabeculectomy or large glaucoma drainage devices (GDDs) with attendant short- and long-term risks. A novel polymer-based microshunt is under review by the US Food and Drug Administration (FDA) for use in adults. The device is attractive for children given the long-term stability of the polymer and the small conjunctival incision required for implantation. This early clinical series explores the safety and efficacy of this device in patients with refractory childhood glaucoma who would otherwise undergo trabeculectomy or implantation of a GDD.

DESIGN

Prospective single-center case series under FDA compassionate use investigational device exemption.

METHODS

FDA and institutional review board approvals were obtained to treat ≤20 children using this investigational device under the compassionate use pathway. Single eyes in patients with refractory childhood glaucoma were treated surgically with the microshunt. Patients with ≥1 year of follow-up are reported.

RESULTS

Twelve eyes of 12 children (15 months to 14 years if age) with mean preoperative intraocular pressure of 22.72 ± 4.8 mm Hg on 3.3 ± 0.65 medications were treated beginning in December 2019. No intraoperative complications occurred. Among eyes with ≥1 year of follow-up (range 12-23 months), 9 were successfully controlled. In this group, preoperative intraocular pressure 21.6 ± 4.9 mm Hg dropped 45% to 11.9 ± 3.8 mm Hg at 1 year; 7 patients were taking no medications at 12 months, and 2 required 2 medications (fixed-combination dorzolamide-timolol). Three eyes failed, requiring additional surgery.

CONCLUSION

These early data suggest that the device is safe and appears effective in patients with refractory childhood glaucoma. A prospective, multicenter pivotal trial is planned.

Compatibility and Durability of the Gel Stent Material

INTRODUCTION

The XEN Gel Stent (AbbVie Pharmaceuticals) is a device made from Gelatin; a well-known material in the medical field that is firm enough to hold its shape and soft enough to conform to tissues and reduce the risk of erosion. The Gel Stent creates a permanent outflow connection between the anterior chamber and subconjunctival space.

AREAS COVERED

Validation testing done on the Gel Stent to evaluate biocompatibility and durability of the material as well as real-world experience are included and discussed in this paper.

EXPERT OPINION

Correlating the results of the preclinical testing, study outcomes available in the published literature, and the surgeons' experiences, the device and materials have shown to have an acceptable biocompatibility and durability profile, with a stable, nondegradable, and permanent implant.

Minimally invasive glaucoma surgery in childhood glaucoma

PURPOSE OF REVIEW

Minimally invasive glaucoma surgery (MIGS) has been shown to be safe and effective in treatment of mild to moderate glaucoma in adults, but reports in childhood glaucoma are limited. We review the available data concerning MIGS and discuss its potential role in childhood glaucoma management.

RECENT FINDINGS

Ab interno counterparts to circumferential ab externo trabeculotomy such as gonioscopy-assisted transluminal trabeculotomy (GATT) and Trab360 show promise in treatment of primary glaucomas as reported in a few retrospective case series. Kahook Dual Blade (KDB) and Trabectome have demonstrated mixed results in few published case reports in children. Small case series and reports suggest that the Xen gel stent can be a safer alternative to traditional filtration surgery, though data on long-term implant and bleb stability are unavailable. Newer devices are being investigated and early results are encouraging.

SUMMARY

GATT and Trab360 seem to be safe, effective methods of achieving circumferential trabeculotomy in childhood glaucoma. KDB, Trabectome, and Xen gel stent have shown some success in selected cases with short-term follow-up. Surgeons must determine the risks and benefits of MIGS over more established methods of intraocular pressure reduction for each individual child. Further research is needed to validate initial findings regarding MIGS in childhood glaucoma.

Multiple XEN Gel Stents for Refractory Pediatric Glaucoma

Although trabeculotomy and goniotomy are currently the mainstay of surgical management for congenital glaucoma, XEN Gel Stent (Allergan) implantation and other microinvasive glaucoma surgery technologies may offer the advantage of having a lower risk of postoperative complications than conventional techniques. A 10-year-old boy presented with aphakic glaucoma in his left eye secondary to previous cataract surgery. Intraocular pressure (IOP) in the left eye at initial presentation was 31 mm Hg with maximal tolerated medical therapy. Surgical history included tube shunt, shunt revision, and subsequent shunt removal. Shunt surgery and revision had been unsuccessful at achieving target IOP. The patient underwent two treatments of micro-pulse transscleral laser therapy that failed to achieve target IOP. At this time, an open conjunctiva ab externo superior XEN Gel Stent (Allergan) was implanted. Within 1 month of surgery, conjunctival dehiscence and contraction occurred. Following this, ab interno inferonasal air-ophthalmic viscosurgical device XEN Gel Stent implantation was performed. In the 6 months following the second XEN Gel Stent, IOP in the left eye was stable at 6 to 8 mm Hg. This report describes the effective use of a XEN Gel Stent implant in the management of congenital glaucoma, while also highlighting a complication. Further studies are required to determine the comparative outcomes of this technique with conventional surgical management. [J Pediatr Ophthalmol Strabismus. 2022;59(1):e11-e14.].

Impact of failed ab-interno trabeculectomy (trabectome) on subsequent XEN45 gel stent implantation in pseudophakic eyes

PURPOSE

To determine the impact of failed ab-interno trabeculectomy on the postoperative outcome of subsequent XEN45 gel stent (Allergan, CA, USA) implantation in pseudophakic eyes.

METHODS

In this retrospective single-center study, we included 60 pseudophakic eyes from 60 participants who underwent XEN45 gel stent implantation. Thirty eyes each underwent primary stent implantation (control group) or had previously undergone a failed ab-interno trabeculectomy (trabectome group). The groups were matched at a 1:1 ratio based on the following criteria: preoperative and maximum Intraocular pressure (IOP), preoperative medication score, cup/disk-ratio, follow-up time, best-corrected visual acuity at baseline, age, and the proportion of patients classified as primary open angle glaucoma or exfoliation glaucoma. We defined a successful surgery by the following three scores: an IOP reduction > 20% and IOP at the longest follow-up < 21 mmHg (Score A) or < 18 mmHg (Score B) or IOP ≤ 15 mmHg and an IOP reduction ≥ 40% (Score C). One open conjunctival revision was allowed in all scores, and a repeat surgery was considered a failure.

RESULTS

Following an average follow-up period of 22 ± 12 months, we observed a mean IOP reduction of 38%, from 23.5 ± 5.2-14.5 ± 5.0 mmHg. Comparative analyses between the groups did not reveal a significant difference in the postoperative IOP, postoperative medication score, side effects, revision rate, repeat surgery rate, or success rate.

CONCLUSIONS

Trabectome is a viable first-line procedure for medically uncontrolled glaucoma before filtering ab-interno microstent surgery is considered.

Failure of XEN Gel Stent Implantation as a Stand-Alone Procedure in Congenital Glaucoma: Case Report of Secondary Congenital Glaucoma in Neurofibromatosis Type 1

A XEN gel stent implant procedure was performed in a one-year-old child with severe unilateral congenital glaucoma. At the age of 6 weeks, an uncomplicated 360° trabeculotomy had been performed, which resulted in intraocular pressure (IOP) control for only 4 months. The gel stent implantation was performed ab interno without complications. However, 1 month later, the stent was repelled into the anterior chamber due to the elasticity of Tenon's layer. A first revision surgery was performed, with excision of Tenon's layer and implantation of a new gel stent under sight. At the age of 18 months, a second revision surgery was performed because of an encapsulated Tenon cyst with insufficient IOP control, again with the implantation of a new stent. At that time, a progressive upper eyelid swelling was apparent. Eyelid biopsy led to the diagnosis of neurofibromatosis type 1, presenting with an orbital plexiform neurofibroma. Further insufficient IOP control resulted in a cyclodestructive procedure and loss of light perception during follow-up. XEN gel stent implantation in congenital glaucoma in infants is more challenging than that in adult patients. Gel stent implantation ab interno may be difficult due to the thickness and elasticity of Tenon's layer. Gel stent dislocation may occur, even months after surgery. Trabeculectomy might be a better approach after failed trabeculotomy in congenital glaucoma. An underlying systemic disease might become apparent late during follow-up.

Long-term Efficacy of Mitomycin C Augmented Trabeculectomy in a Mixed Pediatric Glaucoma Cohort

PRECIS

This paper reports a retrospective consecutive case series investigating the efficacy of Mitomycin C-augmented trabeculectomy in the treatment of primary and secondary pediatric glaucoma in a mixed etiology, multiethnic cohort of patients.

PURPOSE

To evaluate the long-term efficacy and safety of Mitomycin C-augmented trabeculectomy in a mixed, tertiary-referral, pediatric glaucoma cohort.

METHODS

Retrospective consecutive review of all children (37 eyes) undergoing Mitomycin C-augmented trabeculectomy by a single surgeon between 2008 and 2016. Seventeen eyes (45.9%) had primary congenital glaucoma, and 20 eyes (54.1%) had secondary glaucoma. The median age at surgery was 11 months (range, 2 to 146). The mean follow-up was 69.2±4.7 months (range, 3.5 to 107.9).

RESULTS

Overall, trabeculectomy was successful in 80.6% of eyes at 12 months, 60.5% at 3 years, and 57.5% at 5 years. 45.9% cases (17 eyes) required further laser or surgery for uncontrolled intraocular pressure (IOP) and were therefore deemed as failures. The time to failure ranged from 0.4 to 65.1 months (mean, 22.2±5.1 mo). The proportion of children achieving visual acuity of 1.0 LogMAR equivalent or better increased from 43.2% preoperatively to 63.6% at 1 year and 68% at 5 years. The mean IOP reduced from 24.85±0.88 mm Hg preoperatively to 15.14±0.94 mm Hg at 3 months (39% reduction) and 17.42±1.08 mm Hg at 5 years (30% reduction). IOP-lowering medication requirement reduced from 4.14±0.20 agents preoperatively to 0.84±0.22 at 3 months (80% reduction) and 1.78±0.36 at 5 years (57% reduction). There were no sight-threatening complications such as hyphaema, bleb leak, chronic hypotony, endophthalmitis, retinal detachment, or loss of light perception.

CONCLUSIONS

This study provides valuable evidence that Mitomycin C-augmented trabeculectomy is safe and effective as a treatment of primary or secondary pediatric glaucoma, with particularly encouraging results in cases of secondary glaucoma. Trabeculectomy offers the potential for delaying or avoiding glaucoma drainage device surgery in a significant proportion of children.

Bilateral XEN Gel Stent Implantation in Juvenile-Onset Open-Angle Glaucoma

The purpose of the current case is to report the successful management of juvenile-onset open-angle glaucoma with bilateral XEN Gel Stent (Allegran Inc., Irvine, CA) implantation in a patient first diagnosed during pregnancy with co-existing dysautonomia. Treatment with the XEN Gel Stent provided dramatic reductions in intraocular pressure (IOP), and glaucoma medications sustained up to 23 months postoperatively. The success of this case may suggest that this minimally invasive procedure could be an effective treatment option for younger patients who require substantial reductions in IOP and glaucoma medication burden.

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.

Combined Viscodilation of Schlemm's Canal and Collector Channels and 360° Ab-Interno Trabeculotomy for Congenital Glaucoma Associated with Sturge-Weber Syndrome

Purpose

This case report demonstrates the potential role of the OMNI surgical system in the surgical management of congenital glaucoma.

Patients and Methods

The case was a 4-month-old full-term, otherwise healthy female infant with cutaneous hemangiomas of both upper lids, corneal edema in the right eye (RE) and IOP > 30 mmHg. Sturge-Weber syndrome (SWS) was diagnosed. The RE was surgically treated with ab-interno circumferential viscodilation and trabeculotomy.

Results

Through 10 months of follow-up, intraocular pressure was adequately controlled without the need for adjunctive medical therapy.

Conclusion

Given its advantages over other angle surgery techniques, this procedure's role in treating glaucomas of childhood warrants further evaluation.