Comparison of Gonioscopy-assisted Transluminal Trabeculotomy Versus Trabeculectomy With Mitomycin C in Patients With Open-angle Glaucoma

Bent ab interno needle goniotomy versus gonioscopy-assisted transluminal trabeculotomy in primary open-angle glaucoma: study protocol of a randomized clinical trial

BACKGROUND

Minimally invasive glaucoma surgery (MIGS) is a new class of surgeries, which combines moderate to high success rates and a high safety profile. Bent Ab interno Needle Goniotomy (BANG) and Gonioscopy-Assisted Transluminal Trabeculotomy (GATT) are two low-cost MIGS procedures that communicate the anterior chamber to Schlemm's canal. Most of the available publications on MIGS are either case series or retrospective studies, with different study protocols. The aim of this manuscript is to describe a randomized clinical trial (RCT) protocol to compare the long-term intraocular pressure (IOP) control and the safety of both procedures in eyes with primary open-angle glaucoma.

METHODS

This is a parallel, double-arm, single-masked RCT that includes pseudophakic primary open-angle glaucoma (POAG) eyes. After inclusion criteria, medications will be washed out to verify baseline IOP before surgery. Patients will be randomized to BANG or GATT using a sealed envelope. Follow-up visits will be 1, 7, 15, 30, 60, 90, 180, 330 and 360 days after surgery. On PO330, a new medication washout will be done. The main outcome is the IOP reduction following the procedures. Complimentary evaluation of functional and structural parameters, safety, and quality of life will be done after 30, 90, 180, and 360 days.

DISCUSSION

Our study was designed to compare the long-term efficacy and safety of two low-cost MIGS. Most of the published studies on this subject are case series or retrospective cohorts, with different study protocols, which included different types and severities of glaucomas, combined with cataract extraction. Our study only included mild to moderate POAG eyes, with previous successful cataract extraction. Moreover, it provides a standardized protocol that could be replicated in future studies investigating various types of MIGS. This would allow comparison between different techniques in terms of efficacy, safety, and patients' quality of life.

TRIAL REGISTRATION

Retrospectively registered at the Registro Brasileiro de Ensaios Clínicos (ReBEC) platform RBR-268ms5y . Registered on July 29, 2023. The study was approved by the Ethics Committee of the University of Campinas, Brazil.

Comparison of clinical outcomes between gonioscopy-assisted transluminal trabeculotomy and trabeculectomy in advanced-stage pseudoexfoliation glaucoma

PURPOSE

To compare clinical outcomes between gonioscopy-assisted transluminal trabeculotomy (GATT) and trabeculectomy (TRAB) in patients with advanced-stage pseudoexfoliation glaucoma (PEXG).

METHODS

This comparative study comprised 62 patients who underwent GATT (N = 31) or TRAB (N = 31) for advanced-stage PEXG. Primary outcome was cumulative probability of surgical success at the end of 12-month follow-up. Success was determined as intraocular pressure (IOP) reduction ≥ 30% from baseline, IOP between 6 and 18 mmHg and IOP upper limits for IOP < 15 mmHg and < 12 mmHg, separately. Secondary outcomes were IOP reduction, antiglaucoma medication (AGM) use, and complications in the study.

RESULTS

Age, sex, cup/disc ratio, mean deviation, pattern standard deviation, and retinal nerve fiber layer thickness did not significantly differ between the groups (p > 0.05 for all). The probability of cumulative surgical success at the end of 12 months was similar between the two groups for IOP < 15 mmHg and < 18 mmHg but significantly higher after TRAB (92.0%) than GATT (82.5%) for IOP < 12 mmHg (log-rank test p = 0.035). Percentage of IOP reduction from baseline was similar between the groups (53.1 ± 18.6% in GATT group and 53.0 ± 16.6% in TRAB group, p = 0.98) at the end of 12 months. No significant difference in the mean number of AGM was present at the 12-month visit (1.3 ± 1.4 in GATT and 1.1 ± 1.4 in TRAB, p = 0.65).

CONCLUSION

At the end of 12 months, IOP reduction rate was similar between GATT and TRAB. Cumulative surgical success was higher after TRAB than GATT for IOP < 12 mmHg.

Hemi-GATT combined with phacoemulsification in patients with moderate-severe primary open-angle glaucoma: 2-year outcomes

PURPOSE

To describe the outcomes of inferior hemisphere 180° gonioscopy-assisted transluminal trabeculotomy (hemi-GATT) in patients with moderate-severe stage primary open-angle glaucoma (POAG).

METHODS

This single center, retrospective study identified patients with POAG who had undergone combined inferior hemi-GATT with phacoemulsification. Patients with moderate-severe staged POAG were included in the study. Outcome measures included surgical success, intraocular pressure (IOP), number of topical IOP-lowering drops, best-corrected visual acuity (BCVA), visual field mean deviation (MD) and complications. Success was defined using two criteria: Criterion A (IOP <17 mmHg and >20% reduction) and Criterion B (IOP <12 mmHg and >20% reduction).

RESULTS

One hundred-twelve eyes of 112 patients were included in this study. Of these, 91 patients were followed for 24 months or greater to assess endpoint surgical success. Kaplan-Meier survival analysis for Criterion A demonstrated a 64.8% probability of success without topical IOP-lowering therapy (complete success) and a 93.4% probability of success with or without topical IOP-lowering therapy (qualified success). Probabilities of complete and qualified success using Criterion B were 26.4% and 30.8%, respectively. IOP reduction from baseline (21.9 ± 5.8 mmHg) to 24-month follow-up (13.6 ± 3.9 mmHg) was 37.9% for the overall cohort. The most common complication was transient hyphema, which occurred in 25.9% (29 of 112) of patients. All cases of hyphema resolved spontaneously.

CONCLUSIONS

Combined hemi-GATT with phacoemulsification was associated with favorable outcomes and a low complication rate in this study of patients with moderate-severe POAG. Further studies are required comparing hemi-GATT to the 360° approach.

The case for standalone micro-invasive glaucoma surgery: rethinking the role of surgery in the glaucoma treatment paradigm

PURPOSE OF REVIEW

To highlight progress in glaucoma therapy challenging the traditional medication-first approach and present evidence supporting early standalone surgery in the era of micro-invasive glaucoma surgery (MIGS).

RECENT FINDINGS

Medical therapy is limited by well documented poor adherence that compromises the quality of intraocular pressure reduction. Results from modern clinical trials demonstrate advantages of selective laser trabeculoplasty and MIGS procedures in terms of both IOP control and progression risk.

SUMMARY

The MIGS options for pseudophakic or precataractous patients are limited by regulatory rules that require the performance of some procedures only at the time of cataract surgery. These include the iStent/iStent Inject and the Hydrus implants. Nonbleb-forming procedures currently available for standalone use in eyes with mild-moderate primary open-angle glaucoma include gonioscopy-assisted transluminal trabeculotomy (which lowers IOP by 28-61% and medication use by 38-73% in various studies), trabecular ablation with the Trabectome (23-39% and 21-43%, respectively), excisional goniotomy with the Kahook Dual Blade (15-36% and 15-40%, respectively), ab interno canaloplasty (35% and 57%, respectively), and combined canaloplasty and trabeculotomy using the OMNI system (39-40% and 64-73%, respectively). For patients who would benefit from early standalone surgery, these procedures offer meaningful reductions in both IOP and medication burden.

The Efficacy and Safety of the GATT Procedure in Open-Angle Glaucoma-6-Month Results

AIM

The aim of the study was to retrospectively evaluate the efficacy and safety of GATT during a 6-month observation period.

MATERIAL AND METHODS

The studied group consisted of 69 open-angle glaucoma patients treated with GATT as the only procedure or in combination with cataract surgery. Patients were assessed 1 day, 10 days, 1 month, 3 months, and 6 months after the surgery via standard ophthalmic examination including VF, IOP, and BCVA. The number of medications taken daily and possible complications were checked. Two criteria of success were established (S1: IOP decrease by 30% and S2: IOP lower than 18 mm Hg).

RESULTS

Before the surgery, the mean IOP was 26.94 mmHg and significantly decreased after GATT to 15.59 mmHg at 6M. BCVA did not significantly differ between the visits. The mean MD did not change significantly within the 6-month observation period (-8.20 dB vs. -8.16 dB, p = 0.9824), similar to the mean VFI (64.31% vs. 63.05%, p = 0.8571). A 30% IOP decrease at 6M visit was obtained in 95.6% of patients, and 37.7% needed medications to stabilize IOP. An IOP lower than 18 mmHg at 6M was obtained in 91.3% of studied patients after the GATT procedure, and in 58.0% without additional medications. The mean number of medications received daily decreased significantly at 6M compared to preoperative results (2.59 at inclusion vs. 0.76 at 6M, p = 0.0004). The most frequent complication after surgery was hyphema, which resolved spontaneously within 10 days.

CONCLUSION

The 6-month observation showed that GATT is a minimally invasive glaucoma-surgery technique that enables an effective and safe IOP decrease.

Gonioscopy-Assisted Transluminal Trabeculotomy; A Review

AIM

To review the recent evidence in the literature regarding the efficacy and safety of gonioscopy-assisted transluminal trabeculotomy (GATT) in the management of pediatric and adult glaucoma.

METHODS

A literature search was performed in the electronic databases of PubMed, Google Scholar, Embase the Register of Controlled Trials, and Ovid Medline for studies evaluating the safety and outcomes of GATT in glaucoma.

RESULTS

GATT is a novel minimally invasive glaucoma surgery that allows the incision of the inner wall of Schlemm's canal increasing aqueous drainage through the physiologic outflow pathway with subsequent intraocular pressure reduction in different types if of glaucoma.

CONCLUSION

GATT demonstrated favorable results in a wide range of both primary and secondary open-angle and angle-closure glaucoma.

Malignant glaucoma following gonioscopy-assisted transluminal trabeculotomy: a case report

BACKGROUND

To report a case of malignant glaucoma that developed after gonioscopy-assisted transluminal trabeculotomy (GATT).

CASE PRESENTATION

An 85-year-old male pseudophakic patient affected by pseudoexfoliative glaucoma (PEXG), unresponsive to medical glaucoma treatment, underwent uneventful GATT surgery. On the first day after surgery, the eye showed a shallow central and peripheral anterior chamber (AC) with a raised intraocular pressure (IOP) measured at 55 mmHg. Optical coherence tomography and ultrasound biomicroscopy confirmed the diagnosis of malignant glaucoma. Laser iridotomy, posterior capsulotomy and hyaloidotomy were performed, and the patient was treated with atropine sulphate 1%, maximum topical and systemic ocular hypotensive drugs with no improvement in the IOP. Subsequently, the patient underwent pars plana anterior vitrectomy, resulting in deepening of the AC with opening of the iridocorneal angle and decrease of the IOP. No further postoperative complications were recorded, and the IOP remained controlled 12 months after surgery without antiglaucoma medications.

CONCLUSIONS

Despite the minimally invasive profile of GATT, malignant glaucoma may develop after this procedure. Early recognition and prompt treatment are mandatory for preventing permanent visual loss.

Minimally Invasive Glaucoma Surgery-to Remove or Preserve the Trabecular Meshwork: That is the Question?

How to cite this article: Dada T, Mahalingam K, Bhartiya S. Minimally Invasive Glaucoma Surgery—to Remove or Preserve the Trabecular Meshwork: That is the Question? J Curr Glaucoma Pract 2021;15(2):47–51.

Gonioscopy-assisted transluminal trabeculotomy for chronic angle-closure glaucoma: preliminary results

PURPOSE

To report the preliminary results of gonioscopy-assisted transluminal trabeculotomy (GATT) in eyes with chronic angle-closure glaucoma (CACG).

METHODS

Retrospective, single-center, case series of GATT procedures is performed on patients with CACG. The primary outcome was intraocular pressure (IOP). Success was defined as IOP reduction >30% from baseline at 6 and 12 months with (qualified) or without (complete) glaucoma medication. Secondary outcomes were best-corrected visual acuity (BCVA), visual field (VF), peripheral anterior synechiae (PAS), medications, and complications.

RESULTS

Fifteen eyes (15 patients) with a minimum follow-up of 1 year were included for the analysis. Preoperatively, the mean (±SD) IOP was 30.27 (±4.20) mmHg and 15.20 (±2.08) mmHg at 1 year postoperatively (p<0.001). The mean (±SD) percentage of IOP reduction from baseline was 49% (±9.41). At 6 and 12 months, the success rate complete and qualified was 93% (73% and 20%) and 100% (73% and 27%), respectively. BCVA and VF mean deviation were comparable before and after surgery (p=0.167 and p= 0.710, respectively). The median (range) number of glaucoma drugs decreased from 3 (3-4) before to 0 (0-2) after GATT (p<0.001). The absence of PAS was observed in 80% of patients after surgery. Transient hyphema was a common complication requiring aspiration in one case.

CONCLUSION

At 12 months of follow-up, our preliminary results indicate that GATT in CACG effectively reduces the IOP and the number of medication with a low risk of complications. Following ab interno trabeculotomy, an open-angle without PAS was achieved in the majority of patients.

TRIAL REGISTRATION NUMBER

nr. 2016/0010904.