Circumferential Trabeculotomy Research Articles

Contemporary management of refractory pediatric glaucoma

The management of pediatric glaucoma poses a unique challenge in terms of maintaining lifelong vision and combating an aggressive scarring response from surgery. Contemporary literature regarding the surgical management of children with pediatric glaucoma who fail, or are at a high risk of failure, from conventional surgery is limited. The aim of this review is to highlight recent developments in relation to the current opinion regarding the management of children with refractory pediatric glaucoma. Some studies have reported impressive success rates with circumferential trabeculotomy, even in eyes with previous failed surgery. Early results of deep sclerectomy in populations which may not respond well to conventional angle surgery are encouraging but data is limited for the pediatric age group. In compliant patients in whom multiple postoperative examinations under anesthesia are possible, trabeculectomy remains an effective procedure. Multiple recent studies have demonstrated that glaucoma drainage device (GDD) surgery is associated with 5-year success rates of over 70% in primary childhood glaucomas. Glaucoma drainage device surgery is likely to remain a mainstay of surgical management for refractory glaucoma in older children. More prospective data are needed on the success of circumferential trabeculotomy, deep sclerectomy and micropulse laser in pediatric eyes with previous failed surgery. VIDEO ABSTRACT: http://links.lww.com/COOP/A34.

Risk Factors for Complications and Failure after Gonioscopy-Assisted Transluminal Trabeculotomy in a Young Cohort

To determine the risk factors for failures and complications of gonioscopy-assisted transluminal trabeculotomy (GATT) in a young cohort. Retrospective case series. Eyes that underwent GATT at Bascom Palmer Eye Institute. Preoperative and postoperative intraocular pressure (IOP), extent of angle treated, postoperative IOP spike, postoperative drop regimen, and postoperative failure were recorded. Failure was defined as (1) IOP of more than 21 mmHg or less than 5 mmHg after postoperative month 3, (2) absence of at least 20% reduction from the preoperative IOP baseline after postoperative month 3, or (3) performance of additional IOP-lowering surgery before postoperative month 3. Intraocular pressure spike complication was defined as an increase in IOP in the operated eye at any postoperative visit to higher than preoperative IOP within the first 3 months. Kaplan-Meier survival analysis and Cox proportional hazards regression were used to assess the time to events (failure and IOP spike). Risk of failure associated with any of the preoperative, intraoperative, or postoperative variables. A total of 102 eyes of 88 patients were included. The median follow-up time was 7.4 months, with an interquartile range of 3.3 to 13.1 months (standard deviation, 8.7 months). Patients who used corticosteroids after surgery were more likely to experience IOP spikes than those using nonsteroidal anti-inflammatory drugs (NSAIDs) alone (hazard ratio, 3.34; P= 0.042), and patients who underwent noncircumferential trabeculotomy were 2.56 times more likely to experience treatment failure (P= 0.002) compared with those who underwent circumferential surgery. Eyes that received postoperative corticosteroids were more likely to experience an IOP spike complication than those that received postoperative NSAIDs alone, which may suggest corticosteroid-mediated outflow obstruction distal to the trabecular meshwork. Achieving a circumferential trabeculotomy and using only NSAIDs may be more likely to result in surgical success when compared with noncircumferential trabeculotomy or using postoperative corticosteroids.

Surgical Outcomes of Microcatheter-assisted Trabeculotomy as a Secondary Procedure in Patients with Primary Congenital Glaucoma.

PURPOSE:To investigate the efficacy and safety of illuminated microcatheter-assisted trabeculotomy as a secondary procedure in patients with primary congenital glaucoma (PCG).METHODS:This retrospective case series included patients with PCG who underwent trabeculotomy using an illuminated microcatheter with the intent of catheterizing the full circumference of Schlemm's canal in a single procedure. Success was defined as intraocular pressure (IOP) ≤21 mmHg, with or without the use of glaucoma medications. Clinical examination data were collected for up to 36 months postoperatively.RESULTS:Surgery was performed on 16 eyes of 16 patients. The mean patient age was 75.1 ± 69.4 months (range: 4.0–216.0 months). Complete catheterization was achieved in 11 of the 16 eyes (69%), whereas partial catheterization was achieved in five of the 16 eyes (31%). All eyes had previously undergone surgery for PCG. The mean follow-up duration was 20.3 ± 9.0 months (range, 12.0–36.0 months). IOP was reduced from a mean of 31.8 ± 6.6 mmHg preoperatively to 15.6 ± 3.7 mmHg at the final follow-up (P < 0.001). The mean preoperative number of glaucoma medications was 3.9 ± 0.5, which was reduced to 1.1 ± 1.6 at the final follow-up (P = 0.001). Ten (62.5%) of the 16 eyes did not require glaucoma medication by the final follow-up. Early transient postoperative hyphema occurred in six eyes (37.5%). No other complications were noted. All corneas were clear at the final follow-up.CONCLUSION:Ab externo circumferential trabeculotomy using an illuminated microcatheter may be safe and effective as a secondary surgical option for children with PCG after unsuccessful glaucoma surgery.

Emphasis on valid surgical indication for childhood glaucoma

The childhood glaucoma presents high blindness and requires high quality of surgical treatment, laying heavy burdens on patients' families and the society. So far, there is no widely accepted standard and consensus on the surgical treatment for childhood glaucoma. Angle surgery and trabeculotomy, especially microcatheter-assisted circumferential trabeculotomy, have a good therapeutic effect on childhood glaucoma. Established consensus and popularization of the new surgery can significantly improve the success rate of treatment for childhood glaucoma. (Chin J Ophthalmol, 2019, 55: 321-324).

Circumferential Trabeculotomy Versus Conventional Angle Surgery: Comparing Long-term Surgical Success and Clinical Outcomes in Children With Primary Congenital Glaucoma

This study compares the long-term efficacy of circumferential trabeculotomy to that of conventional angle surgeries in primary congenital glaucoma (PCG), as judged by glaucoma and visual outcomes. Retrospective observational case series. Setting: Emory Eye Center, Atlanta, Georgia. This was a single-institution retrospective study involving children with PCG who underwent circumferential trabeculotomy, standard trabeculotomy, or goniotomy with ≥2-year follow-up. Postoperative success (intraocular pressure [IOP] < 22mm Hg ± glaucoma medications, without glaucoma progression/additional IOP-lowering surgery), Snellen-equivalent visual acuity (VA), and IOP at last follow-up. Kaplan-Meier method estimated the probability of glaucoma control vs time postoperatively, and values were compared between angle surgery cohorts using Wilcoxon signed rank tests, Mann-Whitney U tests, and Fisher exact tests. Included were 58 eyes (33 children) after circumferential trabeculotomy and 42 eyes (27 children) after standard trabeculotomy/goniotomy, with mean follow-up of 7.2 ± 4.0 and 8.2 ± 4.5 years, respectively. Postoperative success at last follow-up in the circumferential vs conventional cohorts was 81% (47 of 58 eyes) vs 31% (13 of 42 eyes) (P < .0001). At last follow-up, the circumferential cohort had better median VA than the conventional cohort (20/30 (interquartile range [IQR] 20/25 to 20/70) vs 20/70 (IQR 20/40 to 20/200), P= .009), required fewer glaucoma medications (0.55±1.2 vs 1.61 ± 1.51, P < .0001), had lower IOP in first operated eye (15.2 ± 3.6 vs 18.2 ± 7.0, P= .048), and had comparable incidence of devastating complications (P= .065). In this retrospective study, circumferential trabeculotomy afforded better long-term success and visual outcomes than conventional angle surgery for children with PCG.

Randomized Trial on Illuminated-Microcatheter Circumferential Trabeculotomy Versus Conventional Trabeculotomy in Congenital Glaucoma

To compare 1-year outcomes of illuminated microcatheter-assisted circumferential trabeculotomy (IMCT) vs conventional partial trabeculotomy (CPT) for primary congenital glaucoma (PCG). Randomized clinical trial. Forty eyes of 31 patients with unilateral or bilateral primary congenital glaucoma aged less than 2 years were randomized to undergo IMCT (20 eyes) or CPT (20 eyes). Primary outcome measure was intraocular pressure (IOP) reduction. The success criterion was defined as IOP ≤ 12mm Hg without and with antiglaucoma medications (absolute success and qualified success, respectively). The mean age of our study population was 8.35 ± 1.2months. The mean preoperative IOP was 24.70 ± 3.90mm Hg in the IMCT group and 24.60 ± 3.31mm Hg in the CPT group. Both groups were comparable with respect to preoperative IOP, corneal clarity, corneal diameter, vertical cup-to-disc ratio, and refractive error. In the IMCT group, 360-degree cannulation was achieved in 80% (16/20) of eyes. For the IMCT group and CPT groups, respectively, the absolute success rates were 80% (16/20) and 60% (12/20) (P < .001) and qualified success rates were 90% (18/20) and 70% (14/20) (P < .001). Both procedures produced a statistically significant reduction in IOP, and eyes undergoing IMCT achieved a lower IOP than CPT group eyes at 12months follow-up (9.5 ± 2.4mm Hg and 11.7 ± 2.1mm Hg, respectively, P < .001). In primary congential glaucoma, illuminated microcatheter-assisted 360-degree circumferential trabeculotomy performed better than conventional partial trabeculotomy at 1 year follow-up and resulted in significantly lower IOP measurements.

Two-year results of microcatheter-assisted trabeculotomy in paediatric glaucoma: a randomized controlled study.

To compare the outcomes of microcatheter-assisted circumferential trabeculotomy to standard rigid probe trabeculotomy in childhood glaucomas. Eyes of children requiring trabeculotomy for primary congenital or secondary paediatric glaucoma were randomized to undergo either trabeculotomy using the Glaucolight illuminated microcatheter, or a rigid probe trabeculotomy. Complete success was defined as an intraocular pressure (IOP) of <18mmHg without medications. A total of 62 eyes of 62 patients were included. Of these 30 eyes of 30 patients aged 5.6±4.8months underwent microcatheter-assisted trabeculotomy, with 15 eyes (50%) having a complete 360° cut, while 15 eyes (50%) had an incomplete cut ranging from 250 to 350 degrees. The rigid probe trabeculotomy group included 32 eyes of 32 patients aged 4.4±3.8months. At the end of the 2-year follow-up period, the complete success and the failure rates were 67% and 15%, respectively, in the microcatheter-assisted group versus 47% and 50% in the rigid probe trabeculotomy group (p=0.006). There was a tendency towards lower IOP in the microcatheter group at 1, 3, 6, 12 and 24months postoperatively, with the difference in IOP reaching statistical significance at 6months (p=0.004). The mean survival time was significantly longer for the microcatheter group (p=0.01). At 2years postoperatively, microcatheter-assisted trabeculotomy still yielded superior results in terms of IOP control and success rates in children with primary congenital glaucoma. The need for reoperation for glaucoma was significantly lower in the microcatheter group.

Are the outcomes of circumferential trabeculotomy for adult open angle glaucoma comparable to those of trabeculectomy?

Are the outcomes of circumferential trabeculotomy for adult open angle glaucoma comparable to those of trabeculectomy?

Microcatheter-assisted trabeculotomy versus rigid probe trabeculotomy in childhood glaucoma

PurposeTo compare microcatheter-assisted trabeculotomy with standard rigid probe trabeculotomy for the treatment of childhood glaucoma.MethodsThe early postoperative (12 months) results of microcatheter-assisted trabeculotomy (group 1) performed by single surgeon were...

Micro-invasive 360-degree suture trabeculotomy after successful canaloplasty – one year results.

This study was conducted to analyse the intraocular pressure (IOP)-lowering and drug-sparing effect of micro-invasive 360-degree suture trabeculotomy after successfully performed canaloplasty. This retrospective interventional study included patients with open angle glaucoma or secondary forms of glaucoma, suffering from insufficient IOP level after previously conducted canaloplasty. To enhance the IOP-lowering canaloplasty effect, all patients underwent micro-invasive 360-degree suture trabeculotomy as a conjunctiva-sparing ab interno approach for circumferential trabeculotomy. This was achieved by introducing end-gripping forceps into the anterior chamber with topical anaesthesia, and grasping and extracting the canaloplasty suture through the trabecular meshwork under gonioscopic visualisation. Main outcome measures were IOP reduction and the number of IOP-lowering medications after 3 and 12 moths. Intraoperative and postoperative complications were documented systematically. In total, 88 eyes of 88 patients were included. Mean IOP reduction after micro-invasive 360-degree suture trabeculotomy at month 3 was 37.5 % (from baseline 22.8 ± 6.7 mmHg to 14.3 ± 3.1 mmHg, p < 0.01) and 41.2 % after 12 months (from 22.8 ± 6.7 mmHg to 13.4 ± 2.3 mmHg, p < 0.01). The number of IOP-lowering medications decreased significantly from a mean of 2.7 ± 1.4 to 1.3 ± 1.4 after 3 months, and 1.6 ± 1.2 after 12 months. No serious complications were observed. However, mild or moderate retrograde bleeding from the collector channels was present in 25 % of eyes that resorbed spontaneously in all cases. Micro-invasive 360-degree suture trabeculotomy represents a simple and safe minimal invasive ab interno technique to postoperatively enhance the IOP-lowering and drug-sparing effect of canaloplasty.

Gonioscopy assisted transluminal trabeculotomy: an ab interno circumferential trabeculotomy for the treatment of primary congenital glaucoma and juvenile open angle glaucoma

Background/aimsTo introduce a novel ab interno 360° trabeculotomy for treating primary congenital glaucoma (PCG) and juvenile open angle glaucoma (JOAG) and report preliminary results.MethodsA retrospective chart review of patients who...

Micro-invasive suture trabeculotomy after canaloplasty: preliminary results.

In this study, a conjunctival-sparing ab interno approach for circumferential trabeculotomy, termed micro-invasive suture trabeculotomy (MIST) and its preliminary results are presented. Retrospective case-series in a university setting. A total of 31 patients with open-angle glaucoma with history of canaloplasty. A conjunctival-sparing ab interno approach for circumferential trabeculotomy, termed MIST. Mean decrease of intraocular pressure (IOP) and number of pressure-lowering medications. Mean decrease of IOP was 11.1 mmHg (standard deviation [SD], 9.9 mmHg) at 6 months, 12.1 mmHg (SD, 10.5 mmHg) at 12 months and 13.5 mmHg (SD, 11.4 mmHg) at 24 months. The average percent lowering of IOP was 36.7% (SD, 32.8%) at 6 months, 41.4% (SD, 35.9%) at 12 months and 44.6% (SD, 37.7%) at 24 months. The number of pressure-lowering medications decreased by 1.1 (SD, 1.3) at month 6, by 1.2 (SD, 1.5) at month 12, and by 1.3 (SD, 1.6) at month 24. MIST is a promising approach for the treatment of open-angle glaucoma, which is insufficiently controlled with canaloplasty. The procedure achieved significant and sustained lowering of the intraocular pressure and demonstrated an excellent safety profile. The main advantages of the procedure are: easy to learn, fast to perform, and sparing of the conjunctiva for further filtration surgery, if necessary.

Primary congenital glaucoma.

Primary congenital glaucoma (PCG) is the most common nonsyndromic glaucoma in infancy, which can lead to blindness, or a lifetime of vision when diagnosed and treated properly. PCG is more common in populations with a higher prevalence of consanguinity and is associated with CYP1B1 gene mutations which show variable expressivity and phenotypes. The immature angle appearance of PCG likely results from arrested development of tissues of neural crest origin in the third trimester, with the severity of abnormality varying according to the stage at which arrested development occurred. Classic symptoms at presentation include tearing, photophobia, blepharospasm, eye rubbing, and irritability. Examination may reveal elevated intraocular pressure, corneal edema, increased corneal diameter, Haab striae, or enlarged axial length. Angle surgery remains the first line treatment for PCG with a recent advance being circumferential trabeculotomy with the potential to incise the whole angle during one operation as oppose to an incremental approach and the associated multiple anesthetics. Once angle surgery fails, either trabeculectomy or glaucoma drainage device surgery may be appropriate.

Illuminated Microcatheter Circumferential Trabeculotomy Versus Combined Trabeculotomy-Trabeculectomy for Primary Congenital Glaucoma: A Randomized Controlled Trial

To compare outcomes of illuminated microcatheter-assisted circumferential trabeculotomy vs combined mitomycin C-augmented trabeculotomy-trabeculectomy for primary congenital glaucoma. Prospective, randomized trial. Of the 30 patients (60 eyes) analyzed with bilateral primary congenital glaucoma aged ≤2 years, 1 eye of each patient was randomized to: illuminated microcatheter-assisted trabeculotomy (Group I) or combined trabeculotomy with trabeculectomy augmented with mitomycin C (Group II). Primary outcome measure was intraocular pressure (IOP) reduction. Categorization into absolute success (IOP ≤15mm Hg without medication) and qualified success (IOP ≤15mm Hg with medication) was done. Secondary outcomes included change in corneal diameter and clarity, optic disc status, refraction, need for anti-glaucoma therapy, and occurrence of complications. Mean age of patients was 6.63 ± 5.74months. IOP fell by 49.3% (22.25 ± 10.88 to 11.56 ± 3.33mm Hg) in Group I and 46.6% in Group II (21.73 ± 8.89 to 11.60 ± 3.03mm Hg) (P < .001 in both). At 1 year, absolute success was achieved in 86.7% (26/30) and 90.0% (27/30) in Groups I and II, respectively (P>.99) and qualified success in 93.3% (28/30) in both groups (P= 1). There was significant improvement in corneal clarity (P < .001) and cup-to-disc ratio (P ≤ .01) in both groups at 1 year. Though incidence of hyphema was significantly more in Group I (P= .0001), no vision-threatening complications occurred in either group. Illuminated microcatheter-assisted circumferential trabeculotomy achieved comparable surgical outcomes to mitomycin C-augmented combined trabeculotomy-trabeculectomy and may be recommended as the initial surgical procedure for primary congenital glaucoma.

Comparison of circumferential and traditional trabeculotomy in pediatric glaucoma

Studies have shown high success rates of circumferential trabeculotomy compared to goniotomy. No prior studies have compared traditional trabeculotomy to circumferential trabeculotomy. The aim of this study is to compare intraocular pressure (IOP) control of pediatric glaucoma patients undergoing traditional trabeculotomy (<360°) with those receiving circumferential trabeculotomy (360°).

Childhood glaucoma surgery in the 21st century.

Most children with glaucoma will require surgery in their lifetime, often in their childhood years. The surgical management of childhood glaucoma is however challenging, largely because of its greater potential for failure and complications as compared with surgery in adults. The available surgical repertoire for childhood glaucoma has remained relatively unchanged for many years with most progress owing to modifications to existing surgery. Although the surgical approach to childhood glaucoma varies around the world, angle surgery remains the preferred initial surgery for primary congenital glaucoma and a major advance has been the concept of incising the whole of the angle (circumferential trabeculotomy). Simple modifications to the trabeculectomy technique have been shown to considerably minimise complications. Glaucoma drainage devices maintain a vital role for certain types of glaucoma including those refractory to other surgery. Cyclodestruction continues to have a role mainly for patients following failed drainage/filtering surgery. Although the prognosis for childhood glaucoma has improved significantly since the introduction of angle surgery, there is still considerable progress to be made to ensure a sighted lifetime for children with glaucoma all over the world. Collaborative approaches to researching and delivering this care are required, and this paper highlights the need for more high-quality prospective surgical trials in the management of the childhood glaucoma.

Gonioscopy-assisted transluminal trabeculotomy, ab interno trabeculotomy: technique report and preliminary results.

To introduce a minimally invasive, ab interno approach to a circumferential 360-degree trabeculotomy and to report the preliminary results. Retrospective, noncomparative cases series. Eighty-five eyes of 85 consecutive patients who sought treatment at Glaucoma Associates of Texas with uncontrolled open-angle glaucoma and underwent gonioscopy-assisted transluminal trabeculotomy (GATT) for whom there was at least 6 months of follow-up data. Retrospective chart review of patients who underwent GATT by 4 of the authors (D.S.G., D.G.G., O.S., R.L.F.) between October 2011 and October 2012. The surgery was performed in adults with various open-angle glaucomas. Intraocular pressure (IOP), glaucoma medications, visual acuity, and intraoperative as well as postoperative complications. Eighty-five patients with an age range of 24 to 88 years underwent GATT with at least 6 months of follow-up. In 57 patients with primary open-angle glaucoma, the IOP decreased by 7.7 mmHg (standard deviation [SD], 6.2 mm Hg; 30.0% [SD, 22.7%]) with an average decrease in glaucoma medications of 0.9 (SD, 1.3) at 6months. In this group, the IOP decreased by 11.1 mmHg (SD, 6.1 mmHg; 39.8% [SD, 16.0%]) with 1.1 fewer glaucoma medications at 12 months. In the secondary glaucoma group of 28 patients, IOP decreased by 17.2 mmHg (SD, 10.8 mmHg; 52.7% [SD, 15.8%]) with an average of 2.2 fewer glaucoma medications at 6 months. In this group, the IOP decreased by 19.9 mmHg (SD, 10.2 mmHg; 56.8% [SD, 17.4%]) with an average of 1.9 fewer medications (SD, 2.1) at 12 months. Treatment was considered to have failed in 9% (8/85) of patients because ofthe need for further glaucoma surgery. The cumulative proportion of failure at 1 year ranged from 0.1 to 0.32, depending on the group. Lens status or concurrent cataract surgery did not have a statistically significant effect on IOP in eyes that underwent GATT at either 6 or 12months (P > 0.35). The most common complication was transient hyphema, seen in 30% of patients at the 1-week visit. The preliminary results and safety profile for GATT, a minimally invasive circumferential trabeculotomy, are promising and at least equivalent to previously published results for ab externo trabeculotomy.

Goniotomy versus circumferential trabeculotomy with an illuminated microcatheter in congenital glaucoma

To compare circumferential trabeculotomy performed with an illuminated microcatheter with standard goniotomy for the treatment of congenital glaucoma. The short-term results of catheter-assisted trabeculotomy with an illuminated microcatheter were retrospectively compared with those of goniotomy in patients treated for congenital glaucoma. Success with either approach was defined as an intraocular pressure (IOP) <21 mm Hg with at least a 30% reduction from preoperative pressure levels at 12-month follow-up. Complete success was defined when the target IOP levels were reached without the use of antiglaucoma medication, and qualified success was defined when antiglaucoma drops were required to meet this level of IOP. A total of 24 eyes of 20 patients were included. Microcatheter-assisted circumferential trabeculotomy demonstrated a 91.6% qualified and 83.3% unqualified success rate with 12-month follow-up that exceeded the 53.8% qualified and 46.2% unqualified success rate of conventional goniotomy. In congenital glaucoma, during the first year after surgery, trabeculotomy performed with an illuminated microcatheter appears to be more effective than ab interno goniotomy. No complications were seen in either group; however, the follow-up was relatively short.

Circumferential Trabeculotomy With an Illuminated Microcatheter in Congenital Glaucomas

To determine the safety and efficacy of circumferential trabeculotomy for congenital glaucomas using an illuminated microcatheter. This was a retrospective chart study involving 11 eyes from 7 patients with primary or secondary congenital or juvenile glaucoma who underwent circumferential trabeculotomy performed with an illuminated microcatheter over a 2-year period. Data from eyes with 6 or more months of follow-up intraocular pressure (IOP) data were included in the analysis. Mean IOP was determined along with a survival analysis. Unqualified success was defined as an IOP<21 mm Hg and at least a 30% reduction in IOP without the use of IOP-lowering agents and a qualified success when medications were needed to reach this goal. Mean IOP (mm Hg) was reduced from 33.8±6.3 preoperatively to 18.3±3.5 at the final postoperative visit (P-value<0.001). Length of follow-up was 8 to 12 months (mean of 11 mo). A qualified success was seen in 90.1% of eyes and an unqualified success in 81.8%. If eyes with previous angle surgery were excluded, the unqualified success was 87.5% and the qualified success was 100%. Transient hyphema was seen in all cases. No long-term surgical complications were seen. Circumferential trabeculotomy performed with an illuminated microcatheter provided significant IOP lowering in all patients with unqualified success in the majority of eyes and no significant complications. Further study with even longer follow-up is needed.

Disease-a-Month

To introduce a minimally invasive, ab interno approach to a circumferential 360-degree trabeculotomy and to report the preliminary results.Retrospective, noncomparative cases series.Eighty-five eyes of 85 consecutive patients who sought treatment at Glaucoma Associates of Texas with uncontrolled open-angle glaucoma and underwent gonioscopy-assisted transluminal trabeculotomy (GATT) for whom there was at least 6 months of follow-up data.Retrospective chart review of patients who underwent GATT by 4 of the authors (D.S.G., D.G.G., O.S., R.L.F.) between October 2011 and October 2012. The surgery was performed in adults with various open-angle glaucomas.Intraocular pressure (IOP), glaucoma medications, visual acuity, and intraoperative as well as postoperative complications.Eighty-five patients with an age range of 24 to 88 years underwent GATT with at least 6 months of follow-up. In 57 patients with primary open-angle glaucoma, the IOP decreased by 7.7 mmHg (standard deviation [SD], 6.2 mm Hg; 30.0% [SD, 22.7%]) with an average decrease in glaucoma medications of 0.9 (SD, 1.3) at 6 months. In this group, the IOP decreased by 11.1 mmHg (SD, 6.1 mmHg; 39.8% [SD, 16.0%]) with 1.1 fewer glaucoma medications at 12 months. In the secondary glaucoma group of 28 patients, IOP decreased by 17.2 mmHg (SD, 10.8 mmHg; 52.7% [SD, 15.8%]) with an average of 2.2 fewer glaucoma medications at 6 months. In this group, the IOP decreased by 19.9 mmHg (SD, 10.2 mmHg; 56.8% [SD, 17.4%]) with an average of 1.9 fewer medications (SD, 2.1) at 12 months. Treatment was considered to have failed in 9% (8/85) of patients because of the need for further glaucoma surgery. The cumulative proportion of failure at 1 year ranged from 0.1 to 0.32, depending on the group. Lens status or concurrent cataract surgery did not have a statistically significant effect on IOP in eyes that underwent GATT at either 6 or 12 months (P > 0.35). The most common complication was transient hyphema, seen in 30% of patients at the 1-week visit.The preliminary results and safety profile for GATT, a minimally invasive circumferential trabeculotomy, are promising and at least equivalent to previously published results for ab externo trabeculotomy.