Surgical Outcomes of Gonioscopy-assisted Transluminal Trabeculotomy (GATT) in Patients With Open-angle Glaucoma. J Glaucoma. 2017;26:1137-1143. [PMID: 29035912 DOI: 10.1097/ijg.0000000000000802]

Gonioscopy-Assisted Transluminal Trabeculotomy Outcomes Under Different Levels of Glaucoma Severity: A Multicenter, Comparative Study

PURPOSE

To evaluate the outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) under different levels of glaucoma severity.

DESIGN

Retrospective, multicenter, before-and-after study.

METHODS

One eye from all primary open-angle glaucoma patients who underwent GATT combined with cataract surgery (Phaco-GATT) or GATT stand-alone with 12 months of follow-up were included and divided according to glaucoma severity (mild = GI, moderate = GII, and advanced = GIII) and the outcomes compared.

RESULTS

A total of 270 eyes were included: 90 in GI, 75 in GII, and 105 in GIII. The IOP was reduced from 18.6 ± 6.0 mm Hg in GI, 19.7 ± 6.4 mm Hg in GII, and 21.0 ± 7.9 mm Hg in GIII, preoperatively, to 11.9 ± 2.6 mm Hg in GI, 11.8 ± 2.1 mm Hg in GII, and 11.9 ± 3.0 mm Hg in GIII at 12 months postoperatively (P < .001 for all). The number of hypotensive ocular medications were reduced from 2.7 ± 1.0 in GI, 3.1 ± 0.8 in GII, and 3.2 ± 1.2 in GIII to 0.6 ± 0.9 in GI, 1.0 ± 1.1 in GII, and 1.2 ± 1.1 in GIII at the last postoperative visit (P < .001 for all). Relative success was achieved, at 1 year, in 93.8% of the eyes in GI, 89.0% in GII, and 88.1% in GIII (P = .3). Complete success was achieved in 61.8% of the eyes in GI, 43.8% in GII, and 37.6% in GIII (P = .007). No serious adverse event was observed in any group.

CONCLUSIONS

GATT is a safe and effective procedure in glaucoma, regardless of its preoperative severity.

Efficacy of gonioscopy-assisted transluminal trabeculotomy in advanced-age glaucoma patients

BACKGROUND

The prevalence and severity of many etiologies of glaucoma increase with age, often requiring surgery later in life. Surgery in the most aged demographic, however, poses multiple unique physiologic and psychosocial challenges with variable outcomes. In this study, we evaluate the efficacy and safety of gonioscopy-assisted transluminal trabeculotomy (GATT) in an advanced-age population (>85 years of age).

METHODS

This is a single-centre retrospective cohort study of consecutive patients who underwent GATT at or above 85 years of age. This included patients with GATT of any circumferential extent (90°-360°) with or without concurrent phacoemulsification cataract surgery. The primary outcome measure was proportion of successful surgeries at 1 year by the "complete success" criteria (intraocular pressure [IOP] <17 mm Hg on no medications 3 months after surgery with no additional interventions). Secondary outcomes included proportion of successful surgeries by alternative criteria, cross-sectional analyses of IOPs and medication use, and analyses of postoperative complications and interventions.

RESULTS

Forty eyes of 31 patients were included in the study. Mean baseline IOP was 16.75 ± 7.33 mm Hg on 1.60 ± 1.43 classes of medication. At 1 year, the cumulative survival by Kaplan-Meier analysis was 46.6%. There was a statistically significant reduction in IOP at all postoperative time points to a mean of 11.78 ± 3.07 mm Hg at the last follow-up. There were postoperative complications in 18 eyes, with hyphema and corneal edema accounting for the majority.

CONCLUSIONS

This study provides evidence that GATT is a safe and effective intervention in advanced-age glaucoma populations.

Gonioscopy-Assisted Transluminal Trabeculotomy in Uveitis-Related Ocular Hypertension and Glaucoma

PRCIS

Gonioscopy-assisted transluminal trabeculotomy (GATT) may be an effective first-line surgery for decreasing intraocular pressure (IOP) and medication burden in patients with uveitis-related ocular hypertension (OHT) or glaucoma.

OBJECTIVE

The purpose of the study is to determine the efficacy of GATT in lowering IOP in uveitis-related OHT or glaucoma.

METHODS

Retrospective case series that included patients with uveitis-related OHT or glaucoma who underwent GATT with or without concomitant cataract extraction and intraocular lens implantation at 2 Canadian academic centres from July 2018 to May 2022. Primary outcomes were: complete (no medications) and qualified success (with medication), and failure defined as (1) IOP >21 mm Hg with maximal medical therapy, (2) the need for additional glaucoma procedure, (3) loss of light perception secondary to glaucoma, and (4) IOP <6 mm Hg for 3 months.

RESULTS

Twenty-one eyes from 18 patients were included with a mean preoperative IOP of 26.2 ± 7.3 mm Hg on 4.3 ± 0.7 classes of glaucoma drops. The average follow-up was 29.2 ± 17.6 months and 76% of eyes (n = 16) had reached at least 12 months of follow-up. At the 12-month follow-up visit, there was a significant decrease in average IOP by 9.9 ± 7.9 mm Hg (38%, P = 0.005) and a decrease of 1.9 in glaucoma medication classes ( P = 0.002). Of eyes, 14% achieved complete success, whereas 80% of eyes achieved qualified success. Six eyes failed (29%) and 5 patients (24%) required additional glaucoma surgery. The most common postoperative complication was hyphema (n = 9; 43%).

CONCLUSION

This small case series suggests that GATT may be an effective first-line surgery for decreasing IOP and medication burden in patients with uveitis-related OHT or glaucoma. Further studies with longer follow-ups should be conducted to assess its long-term outcomes.

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 GATT versus micropulse transscleral diode laser cyclophotocoagulation combined with GATT in patients with advanced glaucoma

PURPOSE

To compare the efficacy of gonioscopy-assisted transluminal trabeculotomy (GATT) versus micropulse transscleral diode laser cyclophotocoagulation(MP-TDLC) combined with GATT in the treatment of advanced glaucoma.

METHODS

This retrospective comparative study study included 82 patients (82 eyes) with a diagnosis of advanced glaucoma: 36 patients underwent GATT, and 46 underwent GATT + MP-TDLC. Intraocular pressure (IOP) changes in patients who underwent GATT and GATT MP-TDLC were analyzed retrospectively at regular intervals during the 6-month follow-up period.

RESULTS

For the 82 patients included in this study, the mean ± SD IOPs before the procedures were 27.2 ± 8.5 mmHg in the GATT group and 26.6 ± 6.9 mmHg in the GATT + MP-TDLC group (p = 0.866), and the numbers of glaucoma medications used were 3.41 ± 0.5 in the GATT group and 3.36 ± 0.4 in the GATT + MP-TDLC group (p = 0.605). The mean IOP after GATT was 13.6 ± 3.9 mmHg at day 1, 13.9 ± 3.7 mmHg at week 1, 14.6 ± 4.0 mmHg at month 1, 15.3 ± 4.3 mmHg at month 3, and 14.7 ± 3.3 mmHg at month 6. In the GATT + MP-TDLC group, the postoperative day 1, week 1, month 1, month 3, and month 6 IOP values were 12.4 ± 2.5, 11.8 ± 1.8, 12.1 ± 2.0, 11.8 ± 1.09, and 11.8 ± 1.5 mmHg, respectively.

CONCLUSION

GATT was found to be effective in the treatment of patients with advanced glaucoma, and results closer to the targeted low teens IOP values were obtained with GATT + MP-TDLC.

Intraocular pressure spikes after gonioscopy-assisted transluminal trabeculotomy (GATT)

PURPOSE

Intraocular pressure (IOP) spikes (IOP > 30 mmHg or > 10 mmHg above baseline IOP) are a common and worrisome complication of gonioscopy-assisted transluminal trabeculotomy (GATT). The purpose of this study is to identify risk factors for IOP spikes and to describe their characteristics, management, and clinical course in a large cohort of patients.

METHODS

A retrospective, single-center study which included 217 consecutive eyes of patients that underwent GATT between December 2019 and April 2022 with follow-up of at least 90 days.

RESULTS

IOP spikes occurred in 52 of 217 (24%) eyes. Spikes occurred in 15.5% of patients in whom pre-operative IOP-lowering medications were continued after surgery (90 eyes), and in 29.9% in whom IOP-lowering medications were stopped after surgery (127 eyes). Spikes were diagnosed at a mean of 7.7 ± 6.5 days after surgery. All IOP spikes occurred within the first month of surgery. The mean duration of a spike was 4.9 ± 5.4 days. Management of IOP spikes included adding a mean of 3.13 ± 1.7 groups of glaucoma medications. Thirty-seven (72.5%) eyes were treated with oral carbonic anhydrase inhibitor, 11 (21.6%) were treated with IV mannitol, and anterior chamber paracentesis was performed in 16 (31.4%). Six (11.8%) eyes underwent additional glaucoma surgery to control IOP. Patients that continued their pre-operative IOP-lowering medications after surgery were 2.3 times less likely to develop a spike as compared to patients who discontinued their medications (P = 0.016). Spikes were found to be a risk factor for failure of GATT.

CONCLUSIONS

IOP spikes are a common occurrence after GATT. They most commonly appear during the first two post-operative weeks and usually resolve with topical and systemic IOP-lowering treatment. The continuation of IOP-lowering medications after GATT is recommended to lower the risk of IOP spikes.

Persistent Mydriasis Following Gonioscopy-Assisted Transluminal Trabeculotomy

Herein we describe 2 cases of persistent mydriasis after gonioscopy-assisted transluminal trabeculotomy for open angle glaucoma. Both surgeries were uneventful, but the patients experienced postoperative hyphema and intraocular pressure elevation. They then developed persistent fixed and dilated pupils resistant to pilocarpine that led to intolerable photosensitivity and glare. An iris cerclage pupilloplasty was performed with adequate relief of symptoms in one case.

Minimally Invasive Glaucoma Surgery: Latest Developments and Future Challenges

The development of minimally invasive glaucoma surgeries (MIGSs) was intended to provide safe and modestly efficacious modalities for early intervention of mild-to-moderate glaucoma, with minimal trauma and rapid recovery. They were mainly ab interno procedures that reduce intraocular pressure by facilitating the aqueous outflow by bypassing the trabecular meshwork resistance, reinforcing the uveoscleral flow via the supraciliary space, and reducing aqueous production by the ciliary body. While the cumulating evidence helps shape the role of the available MIGS, the exponential new development and advancement in this field has expanded the territory of MIGS. Apart from developing subconjunctival MIGS filtration devices (Xen gel stent and PRESERFLO MicroShunt), there is a tendency to revisit the "traditional" MIGS for alternative use and to modify the procedures with consideration of the fundamental aqueous outflow physiology. Combined MIGS has also been suggested, based on the theory that their different mechanisms may provide additive or synergistic effects. The advancement of laser procedures is also promising and could supplement unmet needs along the glaucoma treatment algorithm. This review examines the broad array of MIGS, updates the recent findings, discusses their potential alternative applications, and explores future challenges.

Preventing Blindness with Early Cataract Surgery and Micro-Invasive Glaucoma Surgery in Patients Over 50: Guidance for Patients, Physicians and World Governments in Dealing with Glaucoma

Purpose

To offer clinical guidance and address safety and efficacy concerns regarding the growing use of micro-invasive glaucoma surgery (MIGS) as an initial treatment for glaucoma in adult patients.

Design

Narrative literature review.

Methods

A review was conducted to assess outcomes and complications of MIGS in the treatment of glaucoma, both alone and in combination with lens replacement. These outcomes were compared with those of standard glaucoma surgery and/or glaucoma management with medication.

Results

MIGS are effective at lowering intraocular pressure (IOP) over long periods of follow-up. These techniques share a similarly high safety profile between one another. MIGS were found to have lower complication rates and to be more effective in reducing the total amount of medication needed to maintain control of intraocular pressure than standard surgery approaches.

Conclusion

MIGS techniques are growing in popularity and have been demonstrated to be a safe and effective alternative to standard glaucoma surgery. Guidance in the implementation of these procedures has been outlined.

Gonioscopy-Assisted Transluminal Trabeculotomy for the Treatment of Glaucoma in Uveitic Eyes

PURPOSE

To evaluate the outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) in adult eyes with uncontrolled uveitic glaucoma.

METHODS

We reviewed 16 eyes from 13 patients. Surgical success was defined as intraocular pressure (IOP) reduction >20% from baseline or IOP between 5 and 21 mmHg by the 3-month visit while on a stable number or fewer IOP-lowering agents and no need for additional glaucoma surgery.

RESULTS

At 12 months, the cumulative success rate was 81%. Mean IOP was 37.8 ± 13.0 mmHg at baseline and 12.2 ± 3.0 mmHg at 12 months (68% reduction; p < .0001). The average number of glaucoma medications was 4.6 ± 1.3 at baseline and 2.2 ± 0.7 at 12 months (52% reduction; p < .0001). Transient hyphema was seen in 44% of eyes at 1 week.

CONCLUSIONS

This small retrospective study suggests that GATT is effective and safe as an initial surgical treatment for medically refractory glaucoma in uveitic adult eyes.

Gonioscopy-assisted transluminal trabeculotomy in patients with advanced glaucoma

Purpose

To evaluate the efficacy and safety of gonioscopy-assisted transluminal trabeculotomy (GATT) in patients with advanced glaucoma.

Methods

Records of 46 patients with advanced glaucoma were reviewed retrospectively in this single-center chart review. The main outcome measure was surgical success; intra-ocular pressure (IOP) and IOP lowering medication use were secondary outcome measures. Success was defined as an IOP of 18 mmHg or lower (criterion A) or 14 mmHg or lower (criterion B) and one of the following: IOP reduction >30% from baseline on the same or fewer medications or IOP ≤ of baseline on fewer medications as compared to baseline.

Results

Forty-seven eyes were included in the analysis. The average mean deviation was -17.5 ± 7.2 dB (range -8.0 to -33.0). The average follow-up was 6.8 months (range 3.2-22.3). Success at 6 months was 91% for criterion A and 75% for criterion B (n = 33). Mean IOP was reduced from 19.3 ± 6 mmHg (12-40) on 3.7 ± 1.4 medications to 13.2 ± 5.8 mmHg on 1.6 ± 1.4 medications at the 6th post-operative month (P < 0.001 for both IOP and medications). At the last follow-up visit, 37 patients (78%) had an IOP of 14 mmHg or lower, and ten of these patients were unmedicated. Transient hyphema and IOP spikes were the most prevalent adverse events following surgery. Three eyes required further surgery for IOP control. None of the patients lost vision because of surgery.

Conclusions

GATT is a viable surgical option in cases of advanced glaucoma. Careful patient selection and attentive post-operative management are imperative.

Four-year Surgical Outcomes of Gonioscopy-assisted Transluminal Trabeculotomy in Patients with Open-Angle Glaucoma

PURPOSE

To provide 4-year data on the efficacy and safety of gonioscopy-assisted transluminal trabeculotomy (GATT) in patients with open-angle glaucoma.

DESIGN

Retrospective case series.

PARTICIPANTS

Eyes of patients > 18 years of age who underwent GATT by a single surgeon at Wills Eye Hospital with at least 36 months follow-up.

METHODS

Postoperative changes in outcome measures including intraocular pressure (IOP), medication use and visual acuity were recorded. Failure was defined as IOP > 21 mmHg or less than 20% reduction below baseline at any postoperative visit after 3 months or need for further glaucoma surgery.

MAIN OUTCOME MEASURES

Main outcome measures were failure rate, IOP, number of glaucoma medications, and visual acuity at 4 years.

RESULTS

Fifty-nine patients (74 eyes), age 57.1 ± 18.5 years (37.8% female) underwent the GATT procedure. Average follow-up was 47.0 ± 6.7 months (range 35.6-76.5 months). Mean IOP was 27.0 ± 10.0 mmHg preoperatively and 14.8 ± 6.5 mmHg at 4 years (45% IOP decrease; P < 0.01). Mean number of medications decreased from 3.2 ± 1.0 preoperatively to 2.3 ± 1.0 at 4 years (P < 0.01). The cumulative failure rate at 4 years was 53.9%, and the cumulative reoperation rate was 42.0%. No significant differences between patients with primary open-angle glaucoma and other types of glaucoma were found.

CONCLUSIONS

Gonioscopy-assisted transluminal trabeculotomy can be a safe and effective conjunctival-sparing surgery for treating various forms of open-angle glaucoma at 4 years.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Gonioscopy-Assisted Transluminal Trabeculotomy and Goniotomy, With or Without Concomitant Cataract Extraction, in Steroid-Induced and Uveitic Glaucoma: 24-Month Outcomes

PRCIS

Gonioscopy-assisted transluminal trabeculotomy (GATT) and goniotomy with Kahook Dual Blade both achieved sustained reductions in intraocular pressure (IOP) and medication burden in eyes with steroid-induced or uveitic glaucoma at 24 months. Both procedures had favorable safety profiles.

PURPOSE

To characterize the 24-month surgical outcomes of GATT and excisional goniotomy in eyes with steroid-induced or uveitic glaucoma.

PATIENTS AND METHODS

A retrospective chart review was performed of eyes with steroid-induced or uveitic glaucoma that underwent GATT or excisional goniotomy, either standalone or combined with phacoemulsification cataract surgery, by a single surgeon at the Cole Eye Institute. IOP, number of glaucoma medications, and steroid exposure were recorded preoperatively and at multiple postoperative timepoints up to 24 months. Surgical success was defined as at least 20% IOP reduction or IOP <12, 15, or 18 mm Hg (Criterion A, B, or C). Surgical failure was defined as need for additional glaucoma surgery or loss of light perception vision. Intraoperative and postoperative complications were reported.

RESULTS

Forty eyes of 33 patients underwent GATT, and 24 eyes of 22 patients underwent goniotomy, of which 88% and 75%, respectively, had 24-months' follow-up. Concomitant phacoemulsification cataract surgery was performed in 38% (15/40) GATT eyes and 17% (4/24) goniotomy eyes. IOP and number of glaucoma medications were reduced at all postoperative timepoints in both groups. At 24 months, GATT eyes had mean IOP 12.9±3.5 mm Hg on 0.9±1.2 medications, and goniotomy eyes had mean IOP 14.3±4.1 mm Hg on 1.8±1.3 medications. Surgical failure was 8% for GATT and 14% for goniotomy at 24 months. Transient hyphema and transient IOP elevation were the most common complications, and 10% GATT eyes required surgical evacuation of hyphema.

CONCLUSIONS

Both GATT and goniotomy demonstrate favorable efficacy and safety in steroid-induced and uveitic glaucoma eyes. Both procedures achieved sustained reductions in IOP and glaucoma medication burden at 24 months.

Safety and Efficacy of Resident-Performed Gonioscopy-Assisted Transluminal Trabeculotomy

PRCIS

GATT can be performed efficaciously and safely by PGY-3 and PGY-4 residents, with clinical outcomes and complication rates that mirror those of attending-performed GATT cohorts from the literature.

PURPOSE

Report outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) performed by PGY-3 and PGY-4 residents.

METHODS

A retrospective chart review was performed for patients undergoing resident-performed GATT. Eyes with previous traditional glaucoma surgery (trabeculectomy or aqueous shunt) or neovascular glaucoma were excluded from this analysis. The primary aim was to assess whether resident-performed GATTs demonstrated success rates comparable with the GATT literature. Surgical success was defined as intraocular pressure (IOP)<21 mmHg, and an IOP reduction of 20% from baseline, and no subsequent IOP-lowering surgery. The secondary and tertiary aims were to describe complication rates and operating times for resident-performed GATTs, respectively.

RESULTS

A total of 50 eyes from 40 patients with various types of glaucoma were included. Eyes either underwent resident-performed GATT-alone (N=9) or GATT+cataract extraction with intraocular lens implantation (CEIOL) (N=41). The surgical success rate at 6 months was 71% for GATT-alone and 42% for GATT+CEIOL. Three eyes required subsequent IOP-lowering surgery. The hyphema rate was 16% at postoperative week 1 and 6% at postoperative month 1. The IOP spike (>30 mmHg) rate was 18%. Mean surgical time for both GATT-alone and GATT+CEIOL was longer for PGY-4s than for PGY-3s, attributable to less attending assistance during PGY-4 cases and more resident-performed cataracts in PGY-4 GATT+CEIOL cases (85%) compared with PGY-3 cases (35%).

CONCLUSIONS

GATT can be performed efficaciously and safely by PGY-3 and PGY-4 residents, with clinical outcomes and complication rates that mirror those of attending-performed GATT cohorts from the literature.

Gonioscopy-assisted transluminal trabeculotomy for open-angle glaucoma with failed incisional glaucoma surgery: two-year results

BACKGROUND

To evaluate the safety and efficacy of gonioscopy-assisted transluminal trabeculotomy (GATT) in treating patients with open-angle glaucoma (OAG) who had failed prior incisional glaucoma surgery.

METHODS

A consecutive case series of OAG patients aged ≥ 18 who underwent GATT with previous failed glaucoma incision surgery was retrospectively analyzed. Main outcome measures included intraocular pressure (IOP), the number of glaucoma medications, surgical success rate, and occurrence of complications. Success was defined as an IOP of ≤ 21 mmHg and a reduction of IOP by 20% or more from baseline with (qualified success) or without (complete success) glaucoma medications. For eyes with preoperative IOP of < 21 mmHg on 3 or 4 glaucoma medications, postoperative IOP of ≤ 18 mmHg without any glaucoma medications was also defined as complete success.

RESULTS

Forty-four eyes of 35 patients (21 with juvenile-onset open-angle glaucoma and 14 with adult-onset primary open-angle glaucoma) with a median age of 38 years were included in this study. The proportion of eyes with 1 prior incisional glaucoma surgery was 79.5%, and the others had 2 prior surgeries. IOP decreased from 27.4 ± 8.8 mm Hg on 3.6 ± 0.7 medications preoperatively to 15.3 ± 2.7 mm Hg on 0.5 ± 0.9 medications at the 24-month visit (P < 0.001). The mean IOP and the number of glaucoma medications at each follow-up visit were lower than the baseline (all P < 0.001). At 24 months postoperatively, 82.1% of the eyes had IOP ≤ 18 mmHg (versus 15.9% preoperatively, P < 0.001), 56.4% reached IOP ≤ 15 mmHg (versus 4.6% preoperatively, P < 0.001), and 15.4% achieved IOP ≤ 12 mmHg (compared to none preoperatively, P = 0.009). While 95.5% of eyes took 3 or more medications preoperatively, 66.7% did not take glaucoma medication 24 months after GATT. Thirty-four (77.3%) eyes achieved IOP reduction greater than 20% on fewer medications. The complete and qualified success rates were 60.9% and 84.1%, respectively. No vision-threatening complications occurred.

CONCLUSIONS

GATT was safe and effective in treating refractory OAG patients who failed prior incisional glaucoma surgery.

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 Boon to Developing Nations-A Systematic Review

PURPOSE

To systematically review surgical procedure, safety and efficacy of Gonioscopy-Assisted Transluminal Trabeculotomy (GATT).

METHODS

A review of literature was done to analyze all suitable articles from two different databases.

RESULTS

GATT is effective in reducing intraocular pressure and mean number of medications from baseline. It is associated with minimal complications when compared to ab-externo procedures. It has shorter learning curve and can be performed as primary surgical procedure in moderate-to-severe case of open-angle glaucomas.

CONCLUSION

GATT is a minimally invasive surgical procedure for the management of primary and secondary open-angle glaucoma in both adults and children. The advantages of GATT are ab-interno approach, access to open entire natural drainage system, good safety profile and efficacy comparable to trabeculectomy. It can be performed with both illuminated micro-catheter and suture, out of which suture GATT is cost-effective, which is a boon to developing nations.

Causes of Immediate and Early IOP Spikes After Circumferential Gonioscopy-Assisted Transluminal Trabeculotomy Using ASOCT

Purpose

To report the early postoperative causes of intraocular pressure (IOP) spikes after complete circumferential gonioscopy-assisted transluminal trabeculotomy (GATT) using anterior segment optical coherence tomography (ASOCT).

Methods

This was retrospective interventional case series of patients who underwent circumferential GATT by a single surgeon (APR) from 2021 to 2022 at a tertiary eye care in East India and who developed IOP spikes at 1 day-2 weeks (immediate) or early (>2 weeks-2 months) after GATT. The intraocular pressure (IOP), glaucoma medications, and angle evaluation by ASOCT at 1 week, and 1 month were compared between the two groups.

Results

Thirty-two eyes of 32 consecutive patients, aged 40±20.1 years (20 exfoliation glaucoma, 9 juvenile open-angle, and 3 developmental glaucoma), that developed IOP spikes between immediate (n=20) or early (n=12) IOP spikes after GATT, were included. Immediate postoperative spikes were seen in 20 eyes due to retained viscoelastic (n=8), hyphema (n=8) in uncontrolled hypertension, and peripheral anterior synechiae (PAS) (n=6) of which only one eye required medication at 2 months. Causes of immediate IOP spikes on ASOCT included an inverted/reattached trabecular shelf, iris strands in eyes with abnormal iris in developmental glaucoma, and PAS in 1-2 quadrants. Causes of early IOP spikes included PAS >3 quadrants (n=8), and hyperreflective fibrotic tissue over TM (n=4) with 50% requiring medications at 2 months. The ASOCT features predicting the need for medications were PAS >3 quadrants (OR=8.4[2.2-14.3], p=0.03) and fibrotic TM closure (OR=5.4, [3.6-10.2], p=0.003). One eye with macrohyphema 3 days after surgery owing to uncontrolled hypertension (owing to the stoppage of medicines), required additional incisional trabeculectomy within 1 month of surgery.

Conclusion

Immediate IOP spikes are mostly self-resolving as opposed to early IOP spikes >2 weeks that require medications after GATT. Gonioscopic PAS >3 quadrants, and fibrotic TM closure were the main identifiable ASOCT causes predicting the need for medications after GATT.

Relationship of degrees of gonioscopy assisted transluminal trabeculotomy and trabecular shelf to success using a marker suture technique

OBJECTIVE

To evaluate the safety and efficacy of gonioscopy-assisted transluminal trabeculotomy (GATT) using a marker suture which could be a viable low cost alternative to an illuminated micro catheter, by helping the surgeon identify obstruction to suture passage, and estimate the degree of Schlemm's canal cannulated.

SUBJECT/METHODS

Thirty four eyes with 360° of open angles with uncontrolled IOP despite maximal medical therapy, non-compliant to medical therapy or failed incisional glaucoma surgery underwent GATT. 5-0 or 6-0 Prolene® suture was used to cannulate Schlemm's canal. An 8-0 Vicryl® suture was tied around the trailing portion of the Prolene® suture and acted as a guide to estimate the length of Schlemm's canal negotiated. The degree of trabecular shelf seen was noted postoperatively.

RESULTS

Mean baseline IOP was 24.7 ± 8.8 mm Hg (range 13-54 mmHg). Six patients had appositional angle closure and the rest had open angles. Patients were followed up for a period of 45.0 ± 14.6weeks (range 6 weeks-2 years). The mean IOP 6 weeks after surgery was 13 ± 3.3 mm Hg, and at 1 year was 13.5 ± 2.6 mm Hg. Mean degrees of cannulation achieved was 264.5 ± 84.0˚ (90-360˚). The mean number of medications prior to surgery was 2.1 ± 1.0 and at 6 months review was 0.15 ± 0.3. The absolute success was 92.6% 1 year after surgery. Nine patients lost some of their trabecular shelf in the postoperative period, but this did not seem to affect the short term success rate.

DISCUSSION

Suture GATT is a safe and effective procedure to lower IOP even in patients with partial cannulation. Adding a marker suture is a useful adjunct to help identify the length of Schlemm's canal successfully cannulated and monitor progress of the Prolene® suture.

Differences in the Surgical Outcomes of Glaucoma Surgery in Patients of African Caribbean Descent

PURPOSE

People of African Caribbean Descent (ACD) have a higher prevalence of glaucoma compared to people of European Descent (ED) and there is uncertainty if treatment outcomes are equivalent between the two groups. To assess surgical failure rates comparing ACD with ED focusing on trabeculectomy, aqueous shunt implantation, non-penetrating filtering surgery (NPFS), and minimally invasive glaucoma surgery (MIGS) by performing a systematic review in accordance with the PRISMA guidelines and to determine whether there is any evidence in to show a difference in success rates based on race.

METHODS

A systematic review of articles using the CENTRAL, Ovid MEDLINE, PubMed, EMBASE, and ClinicalTrials.gov databases was completed. Additional studies were identified by contacting clinical experts and searching bibliographies. All retrospective and prospective studies on trabeculectomy, aqueous shunt implantation, NPFS, and MIGS that included at least 20% ACD were included. Two review authors independently screened search results for eligibility and inclusion and extracted the data using pre-determined fields.

RESULTS

A total of 76 studies were identified for inclusion in the review. Glaucoma surgical outcomes in ACD appear to be poorer compared to ED overall, particularly for trabeculectomy. Data on NPFS are limited, but the studies completed thus far demonstrate surprisingly good results for ACD, particularly when compared to ED, who have significantly lower pre-operative IOPs. Evidence from studies investigating aqueous shunts does not suggest that ACD have poorer outcomes than ED. There is not enough data on MIGS to provide a significant conclusion.

CONCLUSION

In a population where trabeculectomy may no longer be the gold standard, sufficiently powered studies assessing surgical outcomes in aqueous shunts, NPFS, and MIGS are needed to guide clinicians.

Minimally Invasive Glaucoma Surgery: Safety of Individual Devices

Primary open-angle glaucoma progression in those already on maximal medical therapy has traditionally been treated with trabeculectomy, a surgical procedure that carries a high degree of morbidity. In the last few decades, significant advances have been made in the field of minimally invasive glaucoma surgery (MIGS) devices, which aim to defer or prevent trabeculectomy via less arduous surgical techniques in certain types of glaucoma. Although reviews have been published examining the efficacy of various MIGS techniques, no article synthesises the comparative safety of all available devices. We performed a literature review examining the safety of MIGS devices. Fifteen devices were included, variously attempting to increase aqueous outflow through the trabecular meshwork or the suprachoroidal space, shunting into the subconjunctival space, or reducing aqueous production through ciliary body ablation. Notably, the earliest product attempting to increase outflow to the suprachoroidal space, Alcon's CyPass Micro-Stent, was withdrawn from the market due to concerns regarding increased corneal endothelial cell loss at five years post-implantation. All other devices were described as well-tolerated, with the most common adverse effects including hyphaema, intraocular pressure spikes, and device migration or obstruction. MIGS devices are purported to be uniformly safe, and many studies report no statistically significant increased complications beyond those associated with cataract surgery alone. It is important to note, however, the generally poor quality of current studies, with a dearth of randomised, or even prospective, data, and a large proportion of studies funded by device producers.

Large Hyphema following Femtosecond Laser-assisted Cataract Surgery (FLACS) and Trabectome Resulting in Endocapsular Hematoma

Aim

To report a large hyphema following femtosecond laser-assisted cataract surgery (FLACS) and trabectome resulting in endocapsular hematoma.

Background

Hyphema has previously been described following trabectome, however, no cases have been reported following FLACS or FLACS combined with microinvasive glaucoma surgery (MIGS). We report a case of a large hyphema following FLACS combined with MIGS that resulted in an endocapsular hematoma.

Case description

A 63-year-old myopic female with exfoliation glaucoma underwent FLACS with a trifocal intraocular lens implant and Trabectome in the right eye. Significant intraoperative bleeding ensued following the trabectome and was treated with viscoelastic tamponade, anterior chamber (AC) washout, and cautery. The patient developed a large hyphema with intraocular pressure (IOP) rise that was treated with multiple AC taps, paracentesis, and eye drops. The hyphema took approximately 1 month to completely clear, leaving an endocapsular hematoma. This was treated successfully with Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser posterior capsulotomy.

Conclusion

Hyphema may occur with angle-based MIGS in combination with FLACS and may cause endocapsular hematoma. An increase in episcleral venous pressure during the docking and suction phase of the laser may predispose to bleeding. Endocapsular hematoma is an uncommon finding after cataract surgery and may be treated with Nd:YAG posterior capsulotomy.

How to cite this article

Chang EL, Apostolopoulos N, Mir TA, et al. Large Hyphema following Femtosecond Laser-assisted Cataract Surgery (FLACS) and Trabectome Resulting in Endocapsular Hematoma. J Curr Glaucoma Pract 2022;16(3):195-198.

Size Matters: Ab Interno Canaloplasty Revision with Suture Trabeculotomy

Aim

To report the efficacy of the revision of failed ab interno canaloplasty with micro-invasive suture trabeculotomy (MIST) over a follow-up period of 24 months.

Materials and methods

A retrospective analysis was performed on 23 eyes with open-angle glaucoma (OAG), on whom an ab interno canaloplasty revision with MIST was performed for glaucoma progression. The primary outcome was the proportion of eyes with a significant intraocular pressure (IOP) reduction at 12 months post trabeculotomy, defined as an IOP ≤ 18 mm Hg or ≥20% reduction in IOP without any secondary intervention (SI), and with the same or fewer number of glaucoma medications (NGM). All parameters, including best corrected visual acuity (BCVA), IOP, NGM, and SI, were evaluated at 1, 6, 12, 18, and 24 months.

Results

At 12 months, eight out of 23 eyes (36.4%) achieved complete success, maintained in six eyes (27.3%) at 24 months. A significantly lower mean IOP was recorded at all visits [14.3 ± 4.0 mm Hg at 24 months vs 23.1 ± 6.8 mm Hg at baseline (BL)] with a percent IOP change of up to 27.3% at 24 months postoperatively. NGM and BCVA did not significantly decrease from BL. A total of 11 eyes (47.8%) needed an SI throughout the follow-up period.

Conclusion

Ab interno trabeculotomy in patients with failed canaloplasty was not shown to be effective in providing a satisfactory control of IOP in OAG patients, possibly due to the small suture gauge used in the initial canaloplasty.

Clinical significance

Further research is needed to optimize the surgical outcome.

How to cite this article

Seif R, Jalbout NDE, Sadaka A, et al. Size Matters: Ab Interno Canaloplasty Revision with Suture Trabeculotomy. J Curr Glaucoma Pract 2022;16(3):152-157.

Glaucoma Treatment Outcomes in Open Angle Glaucoma Patients of African Descent

Open angle glaucoma (OAG), characterized by structural changes to the optic nerve head and retinal nerve fiber layer, is a progressive multifactorial optic neuropathy and a leading cause of irreversible blindness globally. Currently, intraocular pressure is the only modifiable risk factor; however, others have been identified, including genetics and race. Importantly, OAG is much more prevalent in persons of African descent (AD) compared with those of European descent (ED). OAG patients of AD are also known to have a more severe course of the disease, a finding potentially explained by structural and/or vascular differences within eye tissues. In addition, disparities in treatment outcomes have been identified in OAG patients of AD. Specifically, prostaglandin analogues have been suggested to be more effective in patients of AD than in those ED, while beta-adrenergic receptors have been suggested to be less effective, although the evidence is inconsistent. AD has also been identified as a risk factor for trabeculectomy failure while laser trabeculoplasty has been conversely found to be very effective in lowering intraocular pressure in patients of AD. Alternative surgical options, including Ex-Press shunt implantation, viscocanalostomy, and canaloplasty are promising in equivalence but require further research to evaluate disparity in outcome properly. In addition to treatment outcomes, social disparities affecting clinical care also exist for AD persons in the form of reduced adherence, access, and choice. Overall, data suggest the need for properly designed prospective trials with AD populations as a primary focus to identify the potential mechanisms driving disparities in treatment and address overall potential bias in glaucoma management.

Outcomes of Prolene Gonioscopy-assisted Transluminal Trabeculotomy in Primary Open-angle Glaucoma and Pseudoexfoliative Glaucoma: A Comparative Study

PRCIS

Gonioscopy-assisted transluminal trabeculotomy (GATT) provides greater intraocular pressure (IOP) reduction in pseudoexfoliative glaucoma (PXG) than in primary open-angle glaucoma (POAG) in the first years of surgery; however, the difference between groups equalizes in the long-term.

PURPOSE

To compare outcomes of GATT in eyes with POAG and PXG.

METHODS

Single-center, retrospective, comparative case series. A total of 202 eyes (91 eyes of POAG; 111 eyes of PXG) were included. GATT was performed as a standalone procedure or in combination with cataract extraction (CE). Outcome measures were change in IOP and number of medications at all time points (1, 3, 6, 9, 12, 18, 24, and 36 mo after surgery), success rate (IOP reduction ≥20% from baseline or IOP between 6-21 mmHg, without further glaucoma surgery), and complication rate. Cumulative success probabilities were compared using Kaplan-Meier survival analyses.

RESULTS

The mean IOP decreased by 8.8 mmHg (34.4%) in the POAG group with a mean decrease of 2 glaucoma medications at final visit. In the PXG group, the mean IOP decreased by 12.8 mm Hg (44.6%) on 2.3 fewer medications. Mean IOP reduction was significantly higher in PXG than POAG at all time points up to 2-year visit (P<0.05 for all), after which the difference was not significant. Cumulative success probability during the first year was significantly higher in PXG (97.6%) than in POAG (86.8%) (P=0.01); no significant difference was found at 2-year (P=0.07) and 3-year visits (P=0.24).

CONCLUSION

GATT was safe and effectively reduced the IOP and medication burden in patients with POAG and PXG. In the first year following GATT, a significantly higher success rate was noted in PXG compared to POAG, however, in subsequent years, the success rate was similar at ~ 75%.

Gonioscopy-Assisted Transluminal Trabeculotomy for Glaucoma: 1-Year Outcomes and Success Predictors

PRCIS

Our results suggest gonioscopy-assisted transluminal trabeculotomy (GATT) as an effective and safe option for the surgical management of open-angle glaucoma (OAG). Older age was the only risk factor for failure in our analysis.

PURPOSE

To report 12-month clinical outcomes, safety profile and success predictors of GATT in patients with OAG.

PATIENTS AND METHODS

A retrospective study of patients (18 y old and above) with medically uncontrolled OAG who underwent GATT as a solo procedure or combined with phacoemulsification (PHACO-GATT) between January 2018 and January 2020. Success at 12 months (primary outcome) was defined as intraocular pressure (IOP) <15 mm Hg, with an IOP reduction of at least 20%, OR a reduction of at least 2 glaucoma medications, compared with baseline. Secondary outcomes were success predictors and safety parameters.

RESULTS

A total of 73 eyes (GATT=38; PHACO-GATT=35) from 58 patients with a mean age of 54.8±11.6 years were included. Overall, after 12 months of follow-up, the mean IOP was reduced from 24.9±8.5 to 12.1±2.1 mm Hg (P<0.001). The mean number of glaucoma medications was reduced from 3.5±0.7 to 1.2±1.2 (P<0.001). The success rate was 87% at 12 months, with no significant differences between GATT (85%) and PHACO-GATT (91%) eyes (P=0.330). Age was the only factor significantly associated with surgical success (hazard ratio=1.35; P=0.012; after adjusting for preoperative IOP and number of glaucoma medications). Patients older than 60 years had a significant greater chance of failure (hazard ratio=10.96; P=0.026) compared with those younger than 60 years. The most common postoperative complication was transient hyphema (39%; median duration, 5 d). No sight-threatening adverse event was documented.

CONCLUSIONS

GATT was effective and safe at lowering IOP with or without cataract extraction in OAG. Patients 60 years or older had a higher risk of failure compared with those younger in age.

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.

Factors Associated With Gonioscopy-Assisted Transluminal Trabeculotomy (GATT) Complications and Failure in Children

PURPOSE

To identify the factors associated with the complications and failure of gonioscopy-assisted transluminal trabeculotomy (GATT) in children.

DESIGN

Retrospective case series.

METHODS

This study was conducted in an institutional setting in a pediatric population (aged <18 years) who had undergone GATT. Records were reviewed, and pre- and postoperative intraocular pressures (IOP), extent of angle treated, medications, complications, and failure were recorded. Failure was defined as IOP >21 mm Hg or <5 mm Hg, absence of at least 20% IOP reduction, performance of additional IOP-lowering surgery, or loss of light perception vision.

RESULTS

A total of 74 eyes of 57 patients were included (mean age, 7.1 years). Over a median follow-up period of 28.5 months, 36 eyes (48.6%) failed. IOP spikes occurred in 25 eyes (33.8%) and were a significant risk factor for failure (hazard ratio [HR] = 2.17; P = .0207). Postoperative hyphema was a significant risk factor for IOP spike (HR = 4.13, P = .003) but not for failure (HR = 0.7, P = .2977). The risk of IOP spike was lowest in eyes treated with nonsteroidal anti-inflammatory drugs (NSAIDs; HR = 0.27, P = .0016). The risk of failure increased significantly in eyes that received topical corticosteroids (compared to NSAIDs; HR = 5.72, P = .0005), in eyes with <360^○ incisions (HR = 4.69, P < .0001), and in younger children.

CONCLUSIONS

GATT is a reasonably effective procedure in childhood glaucoma. Postoperatively, the use of topical NSAIDs (without corticosteroid) may decrease the risk of failure. Eyes with IOP spikes without hyphema are at the highest risk for failure.

Canaloplasty and Trabeculotomy Combined with Phacoemulsification for Glaucoma: 12-Month Results of the GEMINI Study

Purpose

To report 12-month efficacy outcomes of 360° canaloplasty and 180° trabeculotomy using the OMNI surgical system in combination with phacoemulsification in patients with mild-moderate open-angle glaucoma (OAG) and visually significant cataract.

Setting

Fifteen multi-subspecialty ophthalmology practices and surgery centers located in 14 US states.

Design

Prospective, multicenter, IRB approved study of patients treated with canaloplasty (360°) and trabeculotomy (180°). Eligible patients had cataract and mild-moderate OAG with intraocular pressure (IOP) ≤33 mmHg on 1 to 4 hypotensive medications. Unmedicated post-washout mean diurnal IOP (DIOP) ≥21 and ≤36 mmHg.

Methods

Medication washout preoperatively and prior to month 12 DIOP. Effectiveness outcomes were IOP and IOP lowering medication use. Safety outcomes included adverse events and secondary surgical interventions (SSIs). Evaluations at 1, 3, 6, and 12 months.

Results

A total of 149 subjects underwent surgery and 120 were included in the final effectiveness analysis. Mean (standard deviation) unmedicated diurnal IOP was reduced from 23.8 (3.1) mmHg at baseline to 15.6 (4.0) at month 12 (−35%) and medications (before washout) were reduced from 1.8 (0.9) at baseline to 0.4 (0.9) at month 12 (−80%). At month 12, 84.2% of eyes achieved IOP reductions >20% from baseline, 80% of eyes were medication-free, and 76% of eyes achieved IOP between 6–18 mmHg inclusive. Adverse events were uncommon. Most were mild and self-limited including transient hyphema (9 of 149; 6%) and transient IOP elevations (3 of 149; 2.0%). No eyes required SSIs or experienced loss of VA that was attributable to the device or procedure.

Conclusion

Canaloplasty and trabeculotomy performed with the OMNI surgical system at the time of phacoemulsification significantly reduces unmedicated mean diurnal IOP and medication use 12 months postoperatively, with an excellent safety profile. This procedure should be considered for eyes with mild-moderate OAG to reduce IOP, medication burden, or both.

Anterior segment imaging in minimally invasive glaucoma surgery - A systematic review

Minimally invasive glaucoma surgery (MIGS) has grown in popularity over the past decade. This systematic review explores the peri-operative and intraoperative application of anterior segment imaging to maximize the efficacy and safety of MIGS. A review of the PubMed, EMBASE and CINAHL databases was conducted, with inclusion criteria restricted to MIGS that had received United States Food and Drug Administration (FDA) premarket approval, FDA 510(K) premarket notification, or were listed as a class 1 device exempt from FDA approval or notification. 21 manuscripts from 21 unique studies were identified pertaining to MIGS devices including the XEN Gel Stent, Trabectome, iStent Inject, 1st-generation iStent and the Kahook Dual Blade (KDB). Anterior segment imaging modalities included anterior segment optical coherence tomography (AS-OCT), ultrasound biomicroscopy (UBM), aqueous angiography, OCT volumetric scans and in vivo confocal microscopy. Identification and evaluation of aqueous outflow pathways before and after MIGS have potential for improving patient preoperative patient selection and postoperative outcomes. Intraoperative imaging potentially provides the resolution needed for good visualization of angle anatomy and accurate evaluation of surgical endpoints in angle-based MIGS. Anterior segment imaging has been used to identify procedural complications, provide objective information on implant location in relation to surrounding anatomy, assess the post-implantation structural impact of MIGS devices and manage bleb failure and scarring. Technical difficulties in incorporating imaging modalities into the surgical microscope, variable quality of images and optical interference from ocular structures or surgical instruments are remaining barriers, which discourage the widespread clinical use of this technology.

A Prospective Study of Intraocular Pressure Spike and Failure After Gonioscopy-Assisted Transluminal Trabeculotomy in Juvenile Open-Angle Glaucoma: A Prospective Study of GATT in JOAG

PURPOSE

To identify risk factors for surgical failure after gonioscopy-assisted transluminal trabeculotomy (GATT) in juvenile open-angle glaucoma (JOAG).

DESIGN

Prospective, interventional case series.

METHODS

GATT was the initial surgery in 70 eyes of 70 patients with JOAG. Surgical success was defined as a postoperative intraocular pressure (IOP) of ≤21 mm Hg with at least a 20% reduction from preoperative IOP, with or without the use of antiglaucoma medication (qualified and complete success, respectively) at each postoperative visit. IOP spike was defined as IOP >30 mm Hg and an increase of at least 10 mm Hg from IOP before the spike, and then reduced to ≤21 mm Hg.

RESULTS

The median age at the time of surgery was 19.3 years (range, 4.9-37.5 years) with a visual field mean deviation of -17.4 ± 10.6 dB. Mean IOP decreased from 31.3 ± 9.5 mm Hg preoperatively to 15.8 ± 2.7 at 12 months postoperatively. The complete and qualified success rates were 74.3% and 91.4%, respectively. An IOP spike occurred in 52 eyes (74%), with a median spike duration of 3.5 days (range, 1-21 days). Longer duration of IOP spike (P = .009) and older age at the time of surgery (P = .025) were both associated with worse surgical outcomes. Advanced disease was associated with prolonged IOP spike (P = .007).

CONCLUSIONS

GATT provided excellent outcomes in patients with severe JOAG. Older age and longer duration of postoperative IOP spike are risk factors for failure. Severe cases are more likely to have longer durations of IOP spike. Frequent IOP monitoring during the early postoperative period is needed to detect IOP spikes in these patients.

Combined nasal goniotomy - temporal trabeculotomy (NGTT) for circumferential angle surgery in primary congenital glaucoma

PURPOSE

To assess the safety and efficacy of combining nasal goniotomy with temporal trabeculotomy in the management of primary congenital glaucoma.

DESIGN

Case series.

METHODS

Fifteen eyes of eleven children (3-12 months old at presentation) were enrolled in this study after the establishment of PCG diagnosis based on the criteria placed by the World Glaucoma Association. Combined nasal goniotomy and temporal trabeculotomy were done on each eye in an attempt to perform almost 360 degrees circumferential angle surgery without disturbing the superior 180 degrees of conjunctiva to preserve it for future filtering glaucoma surgeries.

RESULTS

By first month, average IOP was 10.5 ± 4.3 mmHg with a 65.3% reduction from average pre-operative IOP. Almost the same percentage of reduction was maintained at 3^rd,6^th and 12^th months postoperative visits with average IOP of 11.9 ± 4.65, 11.8 ± 2.77 and 13 ± 2.82 mmHg (60.7%, 61.1% and 57.2% reduction from pre-operative average). According to success rates, complete success has been achieved in all eyes but one (93.3%), with minor complications in 4 out of 15 eyes (26.6%) that did not affect IOP outcome. Nine out of fifteen eyes completed 18 months post-operative follow-up visits with a successfully, maintained target average IOP of 13.3 ± 3.0 mmHg (57.2% reduction). All of the mean IOP readings during post-operative follow-up period were significantly lower when compared to pre-operative IOP (p < 0.0001). Only one eye had persistently elevated IOP of 26 mmHg at 1^st and 3^rd months post-operatively that necessitated a subsequent subscleral trabeculectomy which succeeded in controlling the pressure bringing it down to 15 mmHg on topical medications.

CONCLUSION

Nasal goniotomy - temporal trabeculotomy (NGTT) is the combination of two well established surgeries that exploits the advantages of circumferential angle surgery while sparing the superior conjunctiva completely for future surgeries if needed. This new procedure was safe and effective in lowering IOP by an average of 60% from pre-operative IOP with a sustained effect till 18 months post-operatively. We believe that this surgery might be added to the armentarium of the surgical management of infantile glaucomas with other circumferential angle surgeries.

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.

Conventional Trabeculotomy versus Gonioscopy-Assisted Transluminal Trabeculotomy: A Retrospective Cohort Study

Background: Conventional trabeculotomy (CT) is performed in an ab-externo manner with at most 120 degrees of incision area of Schlemm’s canal (SC). Recently, gonioscopy-assisted transluminal trabeculotomy (GATT), which makes possible a 360-degree incision area of SC in an ab-interno manner, is introduced. The purpose of this study was to compare surgical outcomes for CT and GATT with and without simultaneous phacoemulsification over 24 months and to identify factors associated with surgical success. Results: Patients’ baseline characteristics were not significantly different between two groups. The surgical success rate in CT and GATT with phacoemulsification groups were 40.4% and 96.6% and were significantly higher in the GATT group than in the CT group (p < 0.001). However, the surgical success rate in CT and GATT without phacoemulsification groups were 40.8% and 54.2%, and there were no significant differences between two groups without phacoemulsification (p = 0.55). Similarly, the postoperative IOP was significantly lower in the GATT group than in the CT group only in eyes with simultaneous phacoemulsification. There were no significant differences in the numbers of glaucoma medications between the two groups. Additional glaucoma surgery was needed in 13.2% and 25.9% of patients in the GATT and CT groups, respectively (p = 0.157). The multivariate logistic regression analysis revealed that the surgical success of trabeculotomy was significantly associated with combined phacoemulsification and the type of glaucoma surgery (GATT). Conclusion: Although both groups without phacoemulsification had a similar surgical success and IOP-lowering effect, GATT combined with phacoemulsification had a higher surgical success rate and a greater IOP-lowering effect compared with combined CT and phacoemulsification. Multivariate logistic regression analysis showed that the factors associated with higher surgical success at one year and two years postoperatively were the combined phacoemulsification procedure and the GATT.

Ab Interno vs. Ab Externo Microcatheter-Assisted Circumferential Trabeculotomy in Treating Patients With Primary Open-Angle Glaucoma

Background: Circumferential trabeculotomy have evolved from ab externo to ab interno approach. Both procedures may lower IOP, but it is unclear which maybe a superior approach.

Purpose: To compare the outcomes of ab interno and ab externo circumferential trabeculotomy in patients with primary open-angle glaucoma.

Design: Retrospective, comparative case series.

Participants: Primary open angle glaucoma patients undergoing ab interno (40 patients in Group 1) or ab externo (54 patients in Group 2) circumferential trabeculotomy, with about one half of them having prior incisional glaucoma surgery.

Methods: Outcomes including intraocular pressure (IOP), glaucoma medications and surgical complications were analyzed.

Main Outcome Measures: IOP, medications and surgical success defined as an IOP of ≤ 21 mmHg and a reduction of IOP ≥20% from baseline (criterion A) or IOP ≤ 18 mmHg and a reduction of IOP 20% from baseline (criterion B) with (qualified success) or without (complete success) medications.

Results: At 1 year, IOP decreased by 37.1% (26.0–14.8 mmHg) in Group 1 and 39.5% (28.5–15.1 mmHg) in Group 2. Medications decreased from 3.5 in Group 1 and 3.6 in Group 2 pre-operatively to 0.6 ± 1.0 and 0.3 ± 0.6 post-operatively, respectively. Success rates did not differ significantly between groups based on criterion A (complete and qualified success: 68.7 and 81.9% in Group 1, and 75.3 and 90.4% in Group 2, respectively) or criterion B (complete and qualified success: 58.2 and 79.3%in Group 1, and 69.5 and 88.4% in Group 2, respectively). For eyes with prior filtration surgeries, the mean percent reduction of IOP (41.7 ± 32.7% in Group 1, 39.7 ± 27.8% in Group 2, P = 0.724) and the mean medication reduction (2.9 ± 1.6 in Group 1, 3.4 ± 1.0 in Group 2, P = 0.454) were not significantly different.

Conclusions: Ab interno circumferential trabeculotomy achieved comparable outcomes to ab externo trabeculotomy and may be an effective surgical option for patients with primary open-angle glaucoma.

Gonioscopy-assisted transluminal trabeculotomy is an effective surgical treatment for uveitic glaucoma

BACKGROUND

To assess the efficacy and safety of gonioscopy-assisted transluminal trabeculotomy (GATT) in uveitic glaucoma (UG).

METHODS

A retrospective interventional case series in which 33 eyes of 32 patients with UG underwent GATT with or without concomitant cataract extraction and intraocular lens implantation (CE/IOL) at three Canadian treatment centres from October 2015 to 2020. The main outcome measure was surgical success defined as an intraocular pressure (IOP) ≤18 mm Hg and at least one of the following: IOP within one mm Hg of baseline on fewer glaucoma medications as compared with baseline or a 30% IOP reduction from baseline on the same or fewer medications. Secondary outcome measures were IOP, medication usage and surgical complications.

RESULTS

Mean patient age (mean±SD) was 49±16 years (range: 18-79) and 44% were female. GATT was performed as a standalone procedure in 52% of cases and the remainder were combined with CE/IOL. Surgical success was achieved in 71.8% (SE: 8.7%) of cases. Mean preoperative IOP (±SD) was 31.4±10.8 mm Hg on a median of 4 medications. 59% of patients were on oral carbonic anhydrase inhibitors (CAIs) prior to surgery. After 1 year, average IOP was 13.8 mm Hg on a median 1 medication, with 6% of patients being on oral CAIs. No sight threatening complications occurred during surgery or follow-up.

CONCLUSION

GATT is an effective surgical strategy in the management of UG. This microinvasive conjunctival-sparing procedure should be considered early in these patients.

Gonioscopy-assisted transluminal trabeculotomy versus goniotomy with Kahook dual blade in patients with uncontrolled juvenile open-angle glaucoma: a retrospective study

Background

To compare the efficacy and safety of gonioscopy-assisted transluminal trabeculotomy (GATT) and Kahook Dual Blade (KDB) excisional goniotomy in patients with uncontrolled juvenile open-angle glaucoma (JOAG).

Methods

Thirty-three patients (46 eyes) were included in this single-center, retrospective, comparative study and treated with GATT (36 eyes) or KDB goniotomy (13 eyes). Intraocular pressure (IOP), number of glaucoma medications, adverse events, and additional anti-glaucoma procedures were collected during pre- and postoperative visits. Surgical success was defined as 6 mmHg ≤ IOP ≤ 18 mmHg and ≥ 20% IOP reduction from baseline with (partial success) or without (complete success) IOP-lowering medications.

Results

The mean ± SD preoperative IOP was 30.48 ± 12.9 mmHg and 26.08 ± 13.1 mmHg (P = 0.164) on 3.71 ± 0.46 and 3.08 ± 0.86 (P = 0.023) glaucoma medications in GATT and KDB group, respectively. At 3 months, the mean ± SD IOP was 15.48 ± 5.93 mmHg and 20.0 ± 10.8 mmHg after GATT and KDB, respectively (P = 0.072). The percentage of IOP lowering from baseline was 44.4 in the GATT group and 14.1 in the KDB group (P = 0.011). The mean reduction in medications was 2.6 ± 1.7 and 0.8 ± 1.2 three months after GATT and KDB, respectively (P < 0.001). Cumulative proportion of partial and complete success were 65.6 and 44.7% in the GATT group, 30.8 and 15.4% in the KDB group at 6 months. Additional procedures were required in 13.9% of cases after GATT and in 61.5% after KDB (P = 0.001). Patients in the GATT group with prior anti-glaucoma procedures and postoperative IOP spikes were more likely to fail, while those with complete trabeculotomy had a better prognosis.

Conclusions

Reduction of IOP and medications were greater after GATT in uncontrolled JOAG eyes. Whereas, more additional IOP-lowering procedures were required after KDB goniotomy.

Trial registration

This study was registered under the Chinese Clinical Trial Registry (ChiCTR2000034172, 27/06/2020).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-02159-z.

Trends and Usage Patterns of Minimally Invasive Glaucoma Surgery in the United States: IRIS® Registry Analysis 2013-2018

PURPOSE

Understanding trends and patterns in the use of minimally invasive glaucoma surgery (MIGS) and patient profiles undergoing each procedure is important given their relative expense and unknown long-term safety and effectiveness.

DESIGN

Retrospective analysis.

PARTICIPANTS

Minimally invasive glaucoma surgeries and standard glaucoma surgeries recorded in the American Academy of Ophthalmology Intelligent Research in Sight (IRIS®) Registry.

METHODS

We used the data from IRIS Registry between 2013 and 2018 (inclusive) to measure the annual number of MIGS and standard surgical techniques (trabeculectomy or glaucoma drainage device [GDD] placement) performed in the United States, stratified by demographic characteristics. Secondary analyses of concurrent surgeries and of subsequent surgeries for MIGS and standard surgical technique also were conducted.

MAIN OUTCOME MEASURES

Trends and sociodemographic characteristics of MIGS use in the United States.

RESULTS

Two hundred three thousand three hundred thirty-two eyes and 232 537 unique procedures had associated, documented International Statistical Classification of Diseases and Related Health Problems (ICD), Ninth or Tenth Revision, codes for glaucoma and were included in final analyses. Among eyes with documented glaucoma diagnoses, a substantial increase in annual MIGS procedures occurred over the study period (from 7586 in 2013 to 39 677) and a smaller decrease in standard glaucoma procedures (from 16 215 to 13 701). The proportion of iStent procedures almost tripled during the study period (from 14% to 40%), and by 2017 accounted for almost half (43.7%) of all glaucoma surgeries in the United States. Twenty-one thousand twenty-five of all eyes (10.3%) underwent multiple procedures: 7638 (36.3%) on the same day and 13 387 (63.7%) on subsequent days. Endocyclophotocoagulation and iStent placement were the most common concurrent procedures (55.4% of all concurrent procedures). Trabeculectomy and GDD placement were most commonly followed by another standard glaucoma surgery, but when followed by sequential MIGS, endocyclophotocoagulation and goniotomy were the most common procedures performed (33.0% and 21.9%, respectively).

CONCLUSIONS

A significant increase in MIGS use occurred over the recent 6-year period, despite limited evidence of their long-term safety or effectiveness, highlighting the need for trials comparing safety and outcomes of novel MIGS versus traditional surgical treatments for glaucoma.

Outcomes of gonioscopy-assisted transluminal trabeculotomy in juvenile-onset primary open-angle glaucoma

PURPOSE

To report the outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) for juvenile-onset primary open-angle glaucoma (JOAG).

METHODS

A consecutive case series of JOAG patients who underwent GATT was reviewed with follow-up period of up to 18 months. Intraocular pressure (IOP), number of glaucoma medications and success rate were compared between eyes with and without prior glaucoma surgery, and between mild-to-moderate and severe cases defined based on Humphrey Visual Field mean deviation.

RESULTS

In total, 59 eyes of 48 patients were included. Overall, IOP was reduced from 26.5 ± 9.0 mmHg on 3.7 ± 0.9 medications preoperatively to 14.7 ± 3.0 mmHg on 0.7 ± 1.2 medications at 12 months and to 14.1 ± 2.3 mmHg on 0.4 ± 0.8 medications at 18 months postoperatively (P < 0.001). The complete and qualified success rates were 70.8% and 81.2% at 12 months, and 58.6% and 81.2% at 18 months, respectively. Eyes with and without prior glaucoma surgery did not differ significantly in terms of postoperative IOP, glaucoma medication and success rate. In addition, GATT was effective for both mild-to-moderate and severe cases; the latter achieved a surgical success of 79.1%.

CONCLUSIONS

GATT is effective for JOAG. In particular, this case series suggests that GATT is promising in treating severe JOAG and those with prior glaucoma surgery.

Outcomes of Gonioscopy-assisted Transluminal Trabeculotomy in Vitrectomized Patients With Secondary Glaucoma After Silicone Oil Removal

PRCIS

The present study demonstrates that surgical success rates of gonioscopy-assisted transluminal trabeculotomy (GATT) with a target intraocular pressure (IOP)≤21 mm Hg are 93.3% (for qualified success) and 26.7% (for complete success) in vitrectomized patients exhibiting secondary open-angle glaucoma (SOAG) after silicone oil (SO) removal, for an average follow-up of 37.5 months.

PURPOSE

To report the long-term outcomes of GATT in vitrectomized patients exhibiting SOAG after SO removal.

SETTING

Retrospective case-series study.

PATIENT POPULATION

This retrospective case-series study enrolled vitrectomized patients who underwent uneventful GATT surgery between May 2014 and May 2019 at Gazi University Hospital for the treatment of medically uncontrolled SOAG after SO removal.

MAIN OUTCOME MEASURES

At baseline and at each postoperative visit, a detailed ophthalmic examination consisting of slit-lamp biomicroscopy, indirect ophthalmoscopy, macular optical coherence tomography, and Goldmann applanation tonometry was performed in all patients. Baseline demographic and clinical characteristics, duration between pars plana vitrectomy and SO removal, duration between SO removal and onset of SOAG, follow-up time, need for antiglaucoma medication, visual acuity, and IOP measurements were noted. Surgical success was defined as an IOP≤21 and ≥6 mm Hg with (qualified success) and without (complete success) IOP-lowering medication.

RESULTS

A total of 15 patients had a history of pars plana vitrectomy with 1000 centistoke SO tamponade before the GATT surgery. GATT was performed in all patients with SOAG after SO removal. The mean age and follow-up of the patients were 53.6±11.8 years (range, 34 to 72 y) and 37.5±15.1 months (range, 12 to 61 mo), respectively. The average duration of SO tamponade in the vitreous cavity was 7.5±1.6 months (range, 5 to 10 mo). The average duration between the SO removal and the development of SOAG was 14.1±13.2 months (range, 2 to 46 mo). The mean IOP decreased from 31.0±4.1 mm Hg at baseline to 15.6±4.6 mm Hg at final visit. The mean final logMAR BCVA was 0.92±0.58 (range, 2 to 0.045). Qualified surgical success was achieved in 14 (93.3%) patients, whereas complete success was achieved in only 4 (26.7%) patients (P<0.001).

CONCLUSIONS

GATT seems to be safe and successful procedure for controlling IOP in patients exhibiting SOAG after SO removal. However, most patients may require antiglaucoma medication during the follow-up, particularly within the first 2 postoperative years.

Minimally Invasive Glaucoma Surgery: A Critical Appraisal of the Literature

Micro- or minimally invasive glaucoma surgeries (MIGS) have been the latest addition to the glaucoma surgical treatment paradigm. This term refers not to a single surgery, but rather to a group of distinct procedures and devices that aim to decrease intraocular pressure. Broadly, MIGS can be categorized into surgeries that increase the trabecular outflow [Trabectome, iStent (first and second generations), Hydrus microstent, Kahook Dual Blade and gonioscopy-assisted transluminal trabeculotomy], surgeries that increase suprachoroidal outflow (Cypass microstent and iStent Supra), and conjunctival bleb-forming procedures (Xen gel stent and InnFocus microshunt). Compared to traditional glaucoma surgeries, such as trabeculectomy and glaucoma drainage device implantation (Ahmed, Baerveldt, and Molteno valves), MIGS are touted to have less severe complications and shorter surgical time. MIGS represent an evolving field, and the efficacy and complications of each procedure should be considered independently, giving more importance to high-quality and longer-term studies.

Prognostic factors affecting the surgical success of gonioscopy-assisted transluminal trabeculotomy

Purpose:

To investigate the prognostic factors affecting gonioscopy-assisted transluminal trabeculotomy (GATT) surgical success.

Methods:

Fifty-three eyes were retrospectively enrolled. Open-angle glaucoma patients with at least 6-month follow-up were included. At baseline, demographic characteristics, intraocular pressure (IOP), number of anti-glaucomatous medications (AG), and glaucoma type were recorded. Postoperatively, IOP, complications, and number of AG were noted. The effects of these parameters on surgical success were investigated.

Results:

The median follow-up time was 13.7 months. The mean IOP decreased from 25.6 ± 6.2 mm Hg at baseline to 14.6 ± 3.5 mm Hg at final, and the number of AG decreased from 3.2 ± 0.78 to 1.2 ± 1.3. When target IOP was considered as 18 mm Hg and 15 mm Hg, surgical success rates were 81.1% and 60.4%, respectively. When target IOP was considered as 18 mm Hg, a positive effect of the combination with cataract surgery and a negative effect of postoperative macrohyphema on success rates were observed. Other factors did not show any association with the success rates for both target IOP values when analyzed by the Cox proportional hazards regression analysis.

Conclusion:

Postoperative macrohyphema may affect surgical success rates negatively. The contribution of the combination with cataract surgery is controversial. Glaucoma stage does not seem to affect surgical success.

Comparison of 1-year surgical outcomes of combined cataract surgery and gonioscopy-assisted transluminal trabeculotomy (GATT) versus cataract surgery and iStent Inject

PURPOSE

Evaluate the efficacy, safety, and complication rates of phacoemulsification cataract surgery when combined with either gonioscopy-assisted transluminal trabeculotomy (GATT) or iStent Inject.

METHODS

This is a retrospective case-control study to compare the surgical outcomes of combined phacoemulsification cataract surgery with either GATT (phaco-GATT) or iStent Inject (phaco-iStent). Both groups had at least 1-year follow-up. The primary outcome measures were IOP and number of glaucoma medications (NGMs) at 1 year. Secondary outcomes measures were best corrected visual acuity (BCVA) and intra- or postoperative complications within the first year of follow-up. Success was defined as intraocular pressure (IOP) < 21 mmHg and ≥ 20% reduction in IOP at 1 year regardless of the NGM.

RESULTS

Each group included 37 patients. The median baseline IOP (24 vs 17) and NGM (3 vs 2) were higher in the phaco-GATT group (p < 0.001). Phaco-GATT achieved a 38% (p < 0.0001) reduction in IOP compared to 13.2% (p < 0.001) in the phaco-iStent group at 1-year follow-up. The reduction in IOP and NGM was significantly higher in the phaco-GATT group (p < 0.01). After adjusting for baseline IOP, the reduction in IOP at 12 months was still significantly higher in the phaco-GATT group (p = 0.042). At 1 year, 86.4% of patients in the phaco-GATT group met the success criteria compared to 35.1% in the phaco-iStent group. Safety outcomes were slightly favourable in the phaco-iStent group.

CONCLUSION

Phaco-GATT and phaco-iStent showed a significant reduction in IOP and NGM, with phaco-GATT having a significantly higher reduction. Phaco-iStent appears to have a higher safety profile and is probably preferable in monocular patients and those with a high risk of bleeding.

Surgical Outcomes of Gonioscopy-Assisted Transluminal Trabeculotomy (GATT) in Patients with Open-Angle Glaucoma - A Retrospective Case Series

PURPOSE

To evaluate the outcome of gonioscopy-assisted transluminal trabeculotomy (GATT) in patients with open-angle glaucoma (OAG).

PARTICIPANTS AND METHODS

A retrospective case series of patients with uncontrolled OAG treated by GATT at the cantonal Hospital Lucerne, a tertiary referral center, between October 2018 and July 2019 with a minimal 6-month follow-up period. Main outcome measures were intraocular pressure (IOP), number of antiglaucoma medications, and complications.

RESULTS

Thirty-one eyes of 29 patients with a mean age of 70.9 years and a minimal follow-up period of 6 months were included in this study. Twenty eyes were treated for pseudoexfoliation (64.5%), seven for primary open-angle (22.6%), three for pigmentary (9.7%), and one for traumatic (3.2%) glaucoma. Twenty-six eyes had data at the 6-month follow-up and 12 eyes at the 12-month follow-up. Twenty-two eyes (70.9%) were pseudophakic prior to the operation. Mean preoperative IOP was 33 mmHg (standard deviation [SD] 8.0 mmHg). The postoperative IOP was 13.9 mmHg [SD 2.2] at the 6- and 13.9 mmHg [SD 3.1] at the 12-month follow-up. The postoperative IOP evolution translated into a 58% decrease between 6 and 12 months (p < 0.001). Thirteen patients (41.9%) were treated with oral Diamox prior to GATT. The number of antiglaucoma medications decreased from a preoperative average of 2.9 [SD 1.2] to postoperative 1 [SD 1] drug (p < 0.001). The most frequent adverse event was the occurrence of postoperative hyphema. Hyphema was observed in 21 (68.0%), 7 (22.6%), and 2 (6.4%) eyes at days 1, 7, and 30 after GATT, respectively. Intraocular hypertension over 25 mmHg was seen in eight eyes (25.8%), and in four of them, a steroid response was suspected. One patient developed an anterior uveitis and a macular edema.

CONCLUSION

GATT is an effective and safe intervention for OAG, particularly in pseudoexfoliation glaucoma (PEX). The advantages of GATT compared to filtration surgery are the low rate of long-term complications and that the intervention is feasible even when difficult conjunctival conditions are encountered.

Microinvasive Glaucoma Surgery: A Review of Schlemm's Canal-Based Procedures

Microinvasive glaucoma surgery has gained popularity over the past decade. It can be performed using three different mechanisms. In the present review, we focused on Schlemm’s canal (SC)-based surgery, which increases aqueous humor (AH) outflow into the aqueous veins by either removal of the trabecular meshwork (TM) or an increase in the tension in the TM. In primary open-angle glaucoma (POAG), the TM is the most likely region for increased AH outflow resistance. Theoretically, removal of the TM can improve the AH outflow; hence, glaucoma specialists focus on microsurgical dissection of the TM. In this review, we analyzed the available literature to examine SC-related microsurgical modalities based on the histopathological proofs of the localization of resistance of the AH outflow. First, we considered the role, anatomy, and physiology of the TM and SC. We referred to studies that describe the mechanisms and potential pathways, related to increased intraocular pressure in the POAG, that are targeted using the SC-related microsurgical interventions. Next, we took a closer look at the gonioscopic tools necessary for an ab-interno approach and explored incision canal surgery: ab-interno trabeculectomy using different instrumentation (Trabectome^®, Kahook Dual Blade) and variations of the technique. Thereafter, we discussed ab-interno canaloplasty, explaining the technique and reviewing its effectiveness. Finally, we presented the scope for future research in the field. Although the iStent also targets SC by bypassing it, this device has been reviewed extensively elsewhere.

12-month interim results of a prospective study of patients with mild to moderate open-angle glaucoma undergoing combined viscodilation of Schlemm's canal and collector channels and 360° trabeculotomy as a standalone procedure or combined with cataract surgery

PURPOSE

To characterize clinical outcomes of combined viscodilation of Schlemm's canal and collector channels and 360° trabeculotomy as a standalone procedure or combined with cataract surgery in eyes with mild to moderate open-angle glaucoma (OAG).

METHODS

In this prospective case series, the OMNI glaucoma surgical platform (Sight Sciences, Menlo Park, CA) was utilized to perform the procedure either combined with phacoemulsification or as a standalone procedure. Changes from baseline in intraocular pressure (IOP) and IOP-lowering medications were evaluated through the first 12 months of a planned 24-month follow-up period.

RESULTS

Among 17 eyes of 15 subjects, mean IOP was reduced from 20.4 mmHg to 12.7-13.7 mmHg through 12 months of follow-up (p < 0.001 at every time point) and mean medications reduced from 2.5 to 0.1-0.6 (p < 0.001 at every time point). IOP reductions in eyes undergoing standalone surgery were approximately 2-4 mmHg greater at each time point compared to eyes undergoing surgery combined with phacoemulsification; this may be related to a higher baseline IOP in the former eyes (22.1 vs 18.5 mmHg). Six eyes developed hyphema, of which three required washout for elevated IOP on the first postoperative day; six additional eyes had IOP elevations that resolved with medical management.

CONCLUSION

Viscodilation of Schlemm's canal and collector channels paired with ab interno trabeculotomy performed with a single integrated instrument (OMNI), whether as standalone or combined with phacoemulsification, effectively lowers both IOP and the need for IOP-lowering medications through 12 months of follow-up.