Outcomes of Gel Stent Implantation for Glaucoma in Patients With Previous Corneal Graft Surgery: A Case Series

Efficacy and Safety of Ab-Interno Canaloplasty in Post-Keratoplasty Patients: 3-Year Results

Purpose

To evaluate the effectiveness and safety of ab-interno canaloplasty (ABiC) for managing intraocular pressure (IOP) in patients following keratoplasty over a three-year period.

Methods

This retrospective analysis focused on post-keratoplasty patients treated with ABiC with the iTrack microcatheter (Nova Eye Medical, Fremont, CA, USA) at a single institution. The study assessed the procedure's impact on IOP control, graft survival, and reliance on topical hypotensive medications, with additional observation for any postoperative complications. Surgical success criteria included the percentage of eyes with IOP ≤15 mmHg, IOP ≤18 mmHg, ≥20% IOP reduction, medication-free eyes, and eyes with concurrent IOP and medication reductions.

Results

ABiC was performed successfully in a cohort of 16 post-keratoplasty (7 penetrating keratoplasty and 9 endothelial keratoplasty (EK)) eyes. Preoperative mean IOP of 25.8±7.2 mmHg was significantly reduced to 13.4±2.9 mmHg (p<0.001) at 1 year postoperatively and maintained at 13.1±3.9 mmHg (p=0.009) at 3 years postoperatively. The mean number of glaucoma medications was 3.5±1.7 at baseline, 2.8±1.3 at 1 year (p=0.107), and 2.5±1.2 at 3 years postoperatively (p=0.088). Eight eyes (66.7%) maintained IOP ≤ 15 mmHg, and 10 eyes (83.3%) maintained ≥ 20% IOP reduction at 3 years. The mean IOP and medication reductions from baseline at 3 years were -49.2% and -28.6%, respectively. Graft clarity was preserved in all patients except for one case of late graft failure that necessitated a repeat EK procedure. Post-ABiC complications included transient hyphema in two patients, neither of which led to long-term adverse outcomes.

Conclusion

ABiC appears to be an effective and safe surgical intervention for sustained IOP reduction in post-keratoplasty patients. Graft survival trends are encouraging, and there was a low incidence of complications over a three-year follow-up period.

Mechanism and treatment of secondary glaucoma after corneal transplantation: a review

Corneal transplantation is a common treatment for corneal diseases. Secondary glaucoma after corneal transplantation is the second leading cause of failure of keratoplasty. This article reviews the mechanism and treatment of secondary glaucoma after corneal transplantation.

Outcomes of XEN Stent in Patients With Glaucoma and Previous Corneal Transplantation

PRCIS

The XEN stent safely and effectively controls intraocular pressure in select patients with history of corneal transplantation.

PURPOSE

Glaucoma is a common complication after corneal transplantation and can be difficult to manage in these patients. This study reports outcomes of XEN stent implantation in eyes with glaucoma in the setting of previous corneal transplantation.

PATIENTS AND METHODS

Noncomparative retrospective case series including eyes with a history of corneal transplantation and subsequent XEN stent implantation by a single glaucoma surgeon in Surrey, British Columbia, between 2017 and 2022. The analysis included patient demographics, pre and postoperative intraocular pressure (IOP), pre and postoperative glaucoma medications, peri and postoperative complications and interventions, and incidence of repeat corneal transplantation and additional glaucoma procedures to control IOP.

RESULTS

Fourteen eyes with previous cornea transplantation underwent XEN stent implantation. Mean age was 70.1 years (range: 47-85 y). Mean follow-up was 18.2 months (range: 1.5-52 mo). The most common glaucoma diagnosis was secondary open angle glaucoma (50.0%). There was a significant reduction in IOP and the number of glaucoma agents at all postoperative time points ( P < 0.05). IOP decreased from 32.7 ± 10.0 mm Hg at baseline to 12.5 ± 4.7 mm Hg at the most recent follow-up. Glaucoma agents decreased from 4.0 ± 0.7 to 0.4 ± 1.0. Two eyes required additional glaucoma surgery to control IOP, with an average time to reoperation of 7 weeks. Two eyes underwent repeat corneal transplantation, with an average time to reoperation of 23.5 months.

CONCLUSIONS

In selected patients with previous corneal transplants and refractory glaucoma, the XEN stent was safely implanted and effectively reduced IOP in the short term.

Surgical Management of Intraocular Pressure With Ab Interno Canaloplasty in Postkeratoplasty Patients: 12-Month Results

PURPOSE

The purpose of this study was to report clinical outcomes of ab interno canaloplasty (ABiC) with the iTrack microcatheter (Nova Eye Medical, Fremont, CA) for surgical management of intraocular pressure (IOP) in postkeratoplasty patients.

METHODS

This study was a single-center retrospective case series of postkeratoplasty eyes undergoing ABiC. Efficacy was evaluated based on graft survivability and mean reduction in IOP at 12 months postoperatively. Secondary end points consisted of visual acuity outcomes, number of topical hypotensive medications, and rate of complications.

RESULTS

ABiC was successfully performed in 17 eyes after keratoplasty (8 penetrating keratoplasty, 6 DSAEK, 2 penetrating keratoplasty + DSAEK, and 1 DMEK) with elevated IOP refractory to topical hypotensive medications. The baseline mean IOP was 26.2 ± 8.4 mm Hg and reduced significantly to 15.0 ± 4.21 mm Hg at 6 months and 13.0 ± 2.99 mm Hg at 12 months ( P < 0.005). The best-corrected visual acuity improved from 0.61 ± 0.55 logMAR at baseline to 0.47 ± 0.59 and 0.49 ± 0.64 at 6 and 12 months, respectively, following ABiC (not statistically significant: P = 0.6769). The baseline mean number of topical hypotensive medications was 3.7 ± 1.8 and reduced to 2.7 ± 1.4 and 2.9 ± 1.3 at 6 and 12 months, respectively ( P = 0.096). One patient developed a hyphema which required anterior chamber washout. One patient required additional glaucoma surgery 19 months after ABiC. No patients experienced graft failure.

CONCLUSIONS

ABiC is a clinically safe and effective treatment that can be performed in postkeratoplasty patients to reduce IOP for at least 1 year without any significant complications.

Clinical Outcomes in Maximum Tolerated Medical Therapy in Penetrating Keratoplasty for Bullous Keratopathy

Purpose

To compare the clinical outcomes of maximum tolerated medical therapy (MTMT) in patients with penetrating keratoplasty (PKP) with those of Ahmed glaucoma valve (AGV) implantation.

Methods

The medical records were retrospectively reviewed in patients who had undergone PKP for bullous keratopathy and were treated with MTMT or AGV implantation for the management of glaucoma. A total of 18 bullous keratopathic patients were investigated between January 2010 and February 2017: 9 patients treated with MTMT and 9 patients treated with AGV implantation. Non-corrected visual acuity (NCVA), intraocular pressure (IOP), endothelial cell density (ECD), hexagonality, coefficient of variation (CV), central corneal thickness (CCT), median survival time of the graft, and the presence of epithelial keratopathy were compared between the groups at each time point or between baseline and after treatment of glaucoma in each group.

Results

There were no significant differences in the visual acuity and corneal thickness between the two groups or within each group over time. Both groups showed a significant reduction in IOP compared with the baseline IOP, and IOP reductions were greater in the AGV group than in the MTMT group (p = 0.040). Significant ECD reductions were found in each group between the baseline and 6 months (p = 0.008 in the MTMT group, p = 0.015 in the AGV group); however, no differences were found between the two groups until 12 months. The significant hexagonality reduction was found in the AGV group between the baseline and 12 months (p = 0.018). The median survival time showed no significant difference in the survival analysis.

Conclusions

Maximum tolerated medical therapy in penetrating keratoplasty for bullous keratopathy seems to similarly affect the endothelial cell density or graft survival when compared with at least 12 month-followed Ahmed glaucoma valve implantation.

Challenges in the complex management of post-keratoplasty glaucoma

Glaucoma is a serious complication after corneal transplantation and itself a common cause for graft failure and leading cause of vision loss post-keratoplasty due to corneal endothelial decompensation. Endothelial keratoplasty procedures like Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) may be superior to penetrating keratoplasty (PK) regarding the incidence of elevated intraocular pressure (IOP) and development of glaucoma. There are indications that regardless of the method of keratoplasty, some corneal diseases like pseudophakic bullous keratopathy, corneal perforation, and graft rejection have a higher risk for developing post-keratoplasty glaucoma than keratoconus and corneal dystrophies and likewise respond less to IOP lowering therapy. In this review, the pathophysiology of post-keratoplasty glaucoma, the diagnostic tools with focus on different devices, and their limitations with regard to measuring IOP and the treatment modalities are presented.

Subconjunctival Ab Externo Gel Stent Implantation for Refractory Glaucoma After High-Risk Penetrating Keratoplasty

This case study reports the successful deployment of the XEN45 gel stent (AbbVie Inc, Chicago, IL) through an ab externo approach in a 73-year-old woman with refractory glaucoma following high-risk penetrating keratoplasty (PK) 10 years prior. The PK was for corneal perforation secondary to peripheral ulcerative keratitis, which required systemic immunosuppression comprising intravenous cyclophosphamide, azathioprine, and corticosteroids to stabilise the disease and prevent corneal graft rejection. The patient’s intraocular pressure was reduced from 40 mmHg preoperatively to 12 mmHg six months after surgery, off medication. The patient’s visual acuity and visual fields remained stable. The XEN45 gel stent utilising the ab externo approach can be considered as a potential tool to lower intraocular pressure in patients with glaucoma after corneal keratoplasty.