WEBVTT
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A 306 degrees glaucoma procedure beats simple needle goniotomy at two years.
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How effective is GAT really?
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Introduction.
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Opening the eye's natural drainage pathway all the way around sounds as though it should lower pressure more than opening only one small section.
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A randomized trial published on September 28, 2026, offers a rare direct comparison.
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Gonioscopy-assisted transluminal trabeculotomy, which opens the drainage pathway through 360 degrees versus a 90-degree procedure using a bent needle.
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At two years, the full circle procedure had better average pressure and medication results.
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But the trial does not prove that treating more degrees alone caused the advantage.
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The treatments differed in both extent and technique, and the study was small.
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Its results support gonioscopy-assisted transluminal tubeculotomy as a promising option for selected patients, not as a guarantee of very low pressure or freedom from future treatment.
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The 2026 randomized trial by Ayub and Costa, what the randomized trial actually studied.
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The trial enrolled 45 eyes from 34 adults at two centers in Brazil.
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Participants had mild to moderate primary open angle glaucoma, were 40 to 80 years old, had already undergone cataract surgery, and were using no more than three pressure-lowering medicines.
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Their treated pressure had to be at least 18 millimeters of mercury at two visits.
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The researchers assigned 23 eyes to gonioscopy-assisted transluminal trabeculotomy, GATT, and 22 to bent abinterno needle goniotomy, bang.
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Patients were masked to their procedure, but the surgeons and examiners could identify it.
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The same experienced surgeon performed all operations.
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In the full circle procedure, the surgeon passed a suture around Schlem's canal and pulled it through, opening the trabecular mesh work through 360 degrees.
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The needle procedure removed a strip of tissue over approximately 90 degrees of the nasal angle.
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So this was not a comparison of the same operation at two different widths.
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Both the instrument and the amount of tissue treated differed.
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Trial meds and eligibility criteria.
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Baseline pressure, two different starting points.
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Before surgery, the average pressure while patients were still using their medicines was 19.87 mm of mercury in the GAT group and 21.18 in the BANG group.
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After a medication washout, the averages were much higher and almost identical, 25.43 and 25.55 respectively.
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The difference between the groups, treated pressures was not statistically significant, but it matters when interpreting percentage reductions.
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The average medication burden was also similar.
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2.35 medicines in the GATT group and 2.41 in the Bang group.
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Participants were mostly older adults, with an average age of about 73.
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The average visual field loss was mild, and all eyes were pseudophagic, meaning they had an artificial lens after cataract surgery.
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Baseline data reported for the trial.
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Two-year results.
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GATT did better, but the details matter.
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At 24 months, average pressure was 15.41 mm of mercury after GATT and 17.79 after bang.
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The paper reported reductions from the on-treatment baseline of 22.44% and 16.0%, respectively.
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Because the GATT group started with a treated average about 1.3 millimeters lower, the difference in the absolute change from those baselines was smaller than the endpoint pressure gap.
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Approximately 4.46 millimeters of reduction for GATT and 3.39 millimeters for BAG, or roughly 1.1 millimeters more reduction for GATT.
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The clearest difference was medication use.
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At two years, the GATT group averaged 0.71 medicines down from 2.35, while the Bang group averaged 2.26 down from 2.41.
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That is a reported reduction of 69.78% versus 6.22%.
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11 GATT eyes and two BANG eyes were medication free.
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The trial's complete success measure was stricter than simply reaching a particular pressure.
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An eye needed to be at or below 18 millimeters of mercury, have at least a 20% reduction, and be off medication.
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Qualified success used the same pressure criteria but allowed medication without increasing the number used at baseline.
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At 24 months, the paper reported 55.5% after bang.
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Qualified success was 64.7% versus 13.6% in the article's results text.
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Its abstract gives 11.4% for bang.
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That small inconsistency is worth noting rather than smoothing over.
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Four GAT eyes reached 12 millimeters of mercury or lower, compared with none after bang.
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4 out of 23 randomized GAT eyes is about 17%.
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Four out of 17 GAT eyes completing follow-up is about 24%.
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Those are simple count-based proportions, not a robust estimate of what an individual patient's chance would be.
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The trial's Kaplan Meyer estimates and its raw eye counts use different methods and denominators.
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Two-year pressure, medication, target, and success results.
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Follow-up measurements.
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Patients were scheduled for visits on postoperative days 1, 7, 15, 30, 60, 90, 180, 360, 540, and 720.
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The journal article's searchable main text gives exact average pressures at inclusion and at 12 and 24 months.
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Earlier visit averages were also reported in a conference abstract from the same study.
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The table below shows those available interim values with the peer-reviewed journal article's numbers used for the final 24-month row.
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The conference report and final paper differ slightly in some late values.
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The final paper should take precedence.
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Neither source's summary gives exact day 15 and day 60 averages.
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For the full table, please open this article on VisualFieldTest.com.
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Pressure is in millimeters of mercury, figures after pylas are standard deviations.
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The day 1 through day 540 values come from the conference report, final 24-month values come from the journal article.
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Conference report, final journal article.
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The pressure rise at day 30 in both groups is a reminder that early postoperative readings can fluctuate.
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In this trial, medicines were not restarted until day 30.
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Afterwards, treatment was reintroduced under a specified protocol if pressure remained above 18 at consecutive visits.
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Early and late averages therefore need to be interpreted in light of the medication schedule, not as measurements taken under identical conditions at every visit.
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Trial follow-up and medication protocol, loss to follow-up, additional procedures, and safety.
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By 24 months, 19 of 22 bang eyes and 17 of 23 GATES had completed follow-up.
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Three Bang Eyes left the protocol because they needed additional glaucoma surgery.
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Six GATEs did not complete it.
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Four needed additional surgery, one had a retinal detachment at day 30, and one patient died.
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Seven eyes had a reoperation, three bang eyes and four GATEs.
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All three bang reoperations were bleb needlings.
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In the GAT group, three were needlings, and one was a trabeculectomy.
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The trial reported no statistically significant difference between groups.
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Needling is a procedure to revise an existing filtering bleb, so these events should not be read as seven newly created blebs from the angle operations themselves.
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The study's failure definition included additional glaucoma surgery.
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Follow-up and reoperation results, at least one complication was recorded in 12 bang eyes, 54.5%, and 17 GAT eyes, 73.9%.
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Iris damage was the most common complication during surgery, and transient hyphema, blood in the front chamber of the eye, was the most common early postoperative problem.
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One GAT eye had a total hyphema on day one.
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It cleared within a week without intervention.
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The retinal detachment occurred 30 days after GAT, but one event in a small study cannot establish that the operation caused it.
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The article also reported a bang eye with persistent corneal edema and cystoid macular edema associated with vitreous prolapse and a poorly positioned artificial lens.
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Some eyes in both groups showed notable reductions in corneal endothelial cell counts.
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At two years, average counts were 1,561, 88 cells per square millimeter after GATT and 1,077.56 after bang.
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The difference between groups was not statistically significant.
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At least a 20% reduction occurred in 30.4% of GATT eyes and 22.7% of Bang eyes.
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These small sample findings warrant follow-up.
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No significant difference does not establish that either procedure has no effect on the cornea.
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Complications and endothelial cell results.
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Does opening more degrees produce more pressure reduction?
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Why a 360-degree opening might help?
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The trabecular meshwork is part of the eye's main fluid drainage route.
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In open angle glaucoma, resistance in this pathway is often too high.
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GET opens the meshwork around the full circumference of Schlem's canal, whereas the trials bang procedure treated about 90 degrees.
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A wider opening could help by reducing resistance over a larger area, reaching more of the eye's drainage channels, and providing alternative routes if some regions drain poorly.
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Outflow is uneven around the eye, so a small opening may happen to reach a less useful region, or it may reach a particularly effective one.
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Healing and scarring could also affect how long any opening stays useful.
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These are plausible explanations, not mechanisms proven by this trial.
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Trial discussion of treatment extent and regional drainage.
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The broader evidence does not show a simple more degrees, more pressure drop rule.
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The 2026 trial is consistent with the idea that full circle treatment can outperform a small sectoral procedure, but it cannot separate the effect of 360 degrees from the effect of using a suture-based trabeculotomy rather than a bent needle tissue removal technique.
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Evidence comparing treatment extents is mixed.
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A randomized trial comparing 180 and 360 degree internal suture trabeculotomy did not establish a simple, reliable advantage from treating the full circle.
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Randomized 180 versus 360-degree trial, a multi-center comparison of 120 and 360-degree goniotomy for primary open-angle glaucoma found broadly similar pressure lowering, with hyphema more common after complete treatment.
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This was not the same as randomizing patients to identical operations that differed only in extent.
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Multicenter partial versus complete goniotomy study.
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A 206-eye observational study found similar outcomes after partial 180 or 270-degree GATT and full 360-degree GATT.
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Because treatment allocation was not randomized, it cannot rule out differences in which eyes were selected for each extent.
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Partial versus complete GATT study.
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In juvenile open angle glaucoma, a study of 120, 240, and 360-degree goniotomy found the two wider treatments performed similarly and better than 120 degrees at six months.
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That result may not apply to older adults with primary open angle glaucoma.
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Juvenile Glaucoma Extent Study, a review of angle procedures, similarly describes studies in which sectoral and circumferential treatments achieved comparable results.
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Taken together, the evidence suggests that extent may matter in some settings, but not in a predictable linear dose response.
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The health and location of the downstream drainage channels, the type of glaucoma, the operation used, and the patient's starting pressure all matter.
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Review of evidence on treating versus preserving the trabecular meshwork.
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How effective is GATT compared with other glaucoma treatments?
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The numbers below are not head-to-head rankings.
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The studies vary in baseline pressure, medication washout, cataract surgery, glaucoma type, success definition, and follow-up.
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In particular, a pressure measured while taking medicines is not directly comparable with an unmedicated pressure after washout.
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For the full table, please open this article on visualfieldtest.com.
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What can we say about reaching 15 or 12?
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The GATT trial reported that 29.3% met its additional success definition of pressure at or below 15 plus at least a 20% reduction.
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That is not the same as the probability of simply measuring 15 or lower at one visit.
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The four GATT eyes that reach 12 or lower are a useful signal, but too few to provide a stable estimate.
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Other studies often report pressure at or below 18 percentage reduction or success under their own rules, not the same thresholds.
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For eye stent, hydris, cannilplasty, laser, and other angle procedures, the literature does not provide a consistent, directly comparable probability of reaching 15 or 12.
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A precise league table of those probabilities would imply more comparability than the studies allow.
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Why trabecular procedures have a pressure ceiling?
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The eye's conventional drainage route ends in veins around the outside of the eye.
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The pressure in those episcleral veins is commonly around 8 to 10 millimeters of mercury.
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Removing resistance at the trabecular meshwork can improve flow, but it does not remove resistance farther downstream or the pressure in the receiving veins.
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A simplified pressure-flow relationship therefore predicts a physiological limit for procedures that rely on the eye's natural drainage route.
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Reviews of eye fluid dynamics also describe meaningful resistance beyond the trabecular meshwork, including around Schlem's canal and its collector channels.
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Trabeculectomy works differently.
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It creates a new route that drains fluid outside the usual pathway and can therefore achieve lower pressures.
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Review of aqueous humor dynamics.
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Review of minimally invasive glaucoma surgery and pressure limits.
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The 8 to 10 figure is not a guaranteed GAT floor.
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It is an estimate of the downstream venous pressure, and real eyes have additional resistance.
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A practical expectation after successful GAT is generally a pressure in the mid-teens, with some eyes reaching the low teens, sometimes with medicines.
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A sustained pressure of 12 or lower is possible in a subset.
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A single-digit result from GAT alone is not a dependable goal.
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If advanced or rapidly progressing glaucoma needs a very low target, a filtering operation may be more appropriate despite its greater risks.
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GATT four-year results.
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Physiology of episcleral venous pressure.
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Which patients may do better with GATT.
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Several factors may affect results, but the evidence is uneven.
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Starting pressure.
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A higher starting pressure can allow a larger numerical reduction, but it does not guarantee success.
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In a four-year GATT series, higher baseline pressure was associated with a modestly higher risk of failure.
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For your study.
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Age and disease severity.
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Studies have not consistently agreed on whether age or glaucoma stage predicts success.
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153 eye study found that glaucoma stage did not appear to affect success, while studies in other populations report different risk patterns.
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Prognostic factor study, previous laser lens status, and combined cataract surgery, the randomized trial included only eyes that had already undergone cataract surgery.
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Its results cannot establish whether GAT performs similarly in phic eyes or when combined with cataract surgery.
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The available evidence does not establish previous selective laser trabeculoplasty as a reliable predictor of GATT success.
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Blood reflux and hyphema.
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Blood reflux can indicate communication with the drainage pathway, but it is not a proven guarantee of durable success.
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Mild transient blood is common after trabecular procedures.
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A prognostic study found that postoperative macrohyphema could be associated with poorer success.
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Prognostic factor study.
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Pigmentation.
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Results from this trial do not answer whether heavily pigmented angles change GAT outcomes.
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Pigmentary glaucoma should not be assumed to have the same risk-benefit profile as the trial's primary open angle glaucoma population.
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As a result, a plausible GAT candidate is someone with an open angle, mild to moderate glaucoma, and a target pressure that may be met in the low to mid-teens, particularly if reducing medication burden and preserving the conjunctiva for possible future surgery are priorities.
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It is less reassuring as a sole plan when the optic nerve needs a very low pressure quickly.
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How much confidence should we place in the trial?
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Observed evidence.
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In this randomized comparison, GATT had better two-year average pressure and medication results than 90-degree bang.
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Its pressure advantage was statistically borderline for the overall time by group analysis, p equal.048, while the medication difference was stronger.
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The trial also found more GATT eyes meeting its success definitions.
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Important limits.
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There were only 45 eyes, and both eyes from some patients were included.
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The researchers used statistical models to account for the correlation between a person's two eyes, but the small sample still makes estimates unstable.
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The GATT group also had more non-completions, including four additional surgeries, a retinal detachment, and a death.
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The procedures could not be masked to examiners, and one surgeon performed all operations.
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The authors themselves noted that the sample limited statistical power for medication outcomes, complications, and survival analysis.
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Trial limitations.
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The treatment extent is another limitation for the central question.
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The comparison was 360-degree suture trabeculotomy versus 90-degree bent needle tissue removal.
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It demonstrates a difference between those two treatment packages.
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It does not prove that a 360-degree version of the same needle procedure would outperform a 90-degree version, or that every additional degree lowers pressure further.
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What might happen in a 500-patient randomized trial?
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The following is an inference, not observed evidence.
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It assumes a study of patients similar to the 2026 trial.
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Pseudophagic adults with mild to moderate primary open angle glaucoma and a treated baseline pressure around 20.
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Average two-year pressure after Gayety, roughly 15.5 to 16.5 mm of mercury.
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Medication reduction, roughly 1.1 to 1.5 medicines on average, leaving many patients on zero or one.
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Medication free at 2 years, perhaps 35 to 50%.
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Pressure of 12 or lower, perhaps 10 to 20%.
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A wide range because the original study recorded only four such eyes.
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Additional glaucoma procedure by two years, perhaps 10 to 20%.
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The original study observed seven reoperations among 45 eyes, but several were bleb needlings.
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A larger trial might produce a different mix.
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Likely five-year durability.
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Many eyes would probably retain some pressure-lowering benefit, but pressure control would not mean permanent freedom from medicines or additional surgery.
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Inference from the four-year observational series suggests that failure and reoperation accumulate with time.
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A reasonable cautious expectation is that a substantial minority will need further treatment by five years.
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In a 500-patient trial, I would expect GATT to retain an advantage over 90 degree bang for medication reduction and probably for average pressure.
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I would not expect the very large success rate difference from the small trial to reproduce exactly.
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A likely average pressure difference may be closer to 1 to 2 mm of mercury than a dramatic separation, and the medication-free advantage could be clinically meaningful without making GATT a substitute for trabeculectomy when a very low target is essential.
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How close can GATT get to trabeculectomy without creating a bleb?
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GATT can be an effective way to lower pressure while preserving the eye's conjunctiva and avoiding a filtering bleb.
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In the randomized two-year trial, its average pressure was about 15.4 millimeters of mercury, and nearly half of the randomized eyes were medication-free by the raw count.
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Larger observational studies also commonly report average pressures in the mid-teens, although longer follow-up brings more failures and additional treatment.
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That is a meaningful result for a patient whose target can be met in the low to mid-teens.
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It is not the same as the pressure-lowering capacity of trabeculectomy.
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Because GATT works through the eye's existing drainage channels, episcleral venous pressure and downstream resistance limit how low pressure can reliably go.
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Low teen pressure is plausible for a good responder.
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A stable pressure of 12 or lower is possible, but not assured.
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Single-digit pressure is not a reliable expectation.
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For people with advanced damage, rapid progression, or a target requiring pressure well below the mid-teens, the greater pressure-lowering potential of trabeculectomy may matter more than the appeal of a bleb-free operation.
00:22:11.680 --> 00:22:23.759
The best choice depends on the individual target pressure, disease severity, drainage anatomy, and tolerance for surgical risk, not simply on whether the procedure treats 90 or 360 degrees.
00:22:23.920 --> 00:22:27.759
All links to sources are available in the text version of this article.
00:22:27.920 --> 00:22:31.839
You can find the full article at visualfieldtest.com.
00:22:32.480 --> 00:22:33.440
Thanks for listening.
00:22:33.599 --> 00:22:39.440
To check your visual field, click the link at the bottom of this article or visit visualfieldtest.com.
00:00:00.000 --> 00:00:04.639
A 306 degrees glaucoma procedure beats simple needle goniotomy at two years.
00:00:04.879 --> 00:00:06.639
How effective is GAT really?
00:00:07.440 --> 00:00:08.560
Introduction.
00:00:09.199 --> 00:00:16.719
Opening the eye's natural drainage pathway all the way around sounds as though it should lower pressure more than opening only one small section.
00:00:16.960 --> 00:00:22.800
A randomized trial published on September 28, 2026, offers a rare direct comparison.
00:00:23.039 --> 00:00:33.359
Gonioscopy-assisted transluminal trabeculotomy, which opens the drainage pathway through 360 degrees versus a 90-degree procedure using a bent needle.
00:00:33.600 --> 00:00:38.960
At two years, the full circle procedure had better average pressure and medication results.
00:00:39.200 --> 00:00:43.759
But the trial does not prove that treating more degrees alone caused the advantage.
00:00:44.000 --> 00:00:48.799
The treatments differed in both extent and technique, and the study was small.
00:00:49.280 --> 00:01:01.280
Its results support gonioscopy-assisted transluminal tubeculotomy as a promising option for selected patients, not as a guarantee of very low pressure or freedom from future treatment.
00:01:01.600 --> 00:01:07.840
The 2026 randomized trial by Ayub and Costa, what the randomized trial actually studied.
00:01:08.560 --> 00:01:13.200
The trial enrolled 45 eyes from 34 adults at two centers in Brazil.
00:01:13.359 --> 00:01:24.560
Participants had mild to moderate primary open angle glaucoma, were 40 to 80 years old, had already undergone cataract surgery, and were using no more than three pressure-lowering medicines.
00:01:24.799 --> 00:01:29.760
Their treated pressure had to be at least 18 millimeters of mercury at two visits.
00:01:29.920 --> 00:01:40.640
The researchers assigned 23 eyes to gonioscopy-assisted transluminal trabeculotomy, GATT, and 22 to bent abinterno needle goniotomy, bang.
00:01:41.120 --> 00:01:45.840
Patients were masked to their procedure, but the surgeons and examiners could identify it.
00:01:46.000 --> 00:01:49.120
The same experienced surgeon performed all operations.
00:01:49.840 --> 00:01:59.599
In the full circle procedure, the surgeon passed a suture around Schlem's canal and pulled it through, opening the trabecular mesh work through 360 degrees.
00:01:59.840 --> 00:02:05.840
The needle procedure removed a strip of tissue over approximately 90 degrees of the nasal angle.
00:02:06.079 --> 00:02:10.319
So this was not a comparison of the same operation at two different widths.
00:02:10.560 --> 00:02:14.080
Both the instrument and the amount of tissue treated differed.
00:02:14.639 --> 00:02:17.199
Trial meds and eligibility criteria.
00:02:17.439 --> 00:02:20.479
Baseline pressure, two different starting points.
00:02:20.719 --> 00:02:31.759
Before surgery, the average pressure while patients were still using their medicines was 19.87 mm of mercury in the GAT group and 21.18 in the BANG group.
00:02:31.919 --> 00:02:40.400
After a medication washout, the averages were much higher and almost identical, 25.43 and 25.55 respectively.
00:02:40.719 --> 00:02:48.800
The difference between the groups, treated pressures was not statistically significant, but it matters when interpreting percentage reductions.
00:02:49.039 --> 00:02:52.159
The average medication burden was also similar.
00:02:52.479 --> 00:02:57.199
2.35 medicines in the GATT group and 2.41 in the Bang group.
00:02:57.360 --> 00:03:02.080
Participants were mostly older adults, with an average age of about 73.
00:03:02.400 --> 00:03:10.240
The average visual field loss was mild, and all eyes were pseudophagic, meaning they had an artificial lens after cataract surgery.
00:03:10.400 --> 00:03:12.479
Baseline data reported for the trial.
00:03:12.719 --> 00:03:13.759
Two-year results.
00:03:14.000 --> 00:03:16.560
GATT did better, but the details matter.
00:03:16.719 --> 00:03:24.240
At 24 months, average pressure was 15.41 mm of mercury after GATT and 17.79 after bang.
00:03:24.560 --> 00:03:32.240
The paper reported reductions from the on-treatment baseline of 22.44% and 16.0%, respectively.
00:03:32.479 --> 00:03:42.240
Because the GATT group started with a treated average about 1.3 millimeters lower, the difference in the absolute change from those baselines was smaller than the endpoint pressure gap.
00:03:42.479 --> 00:03:52.719
Approximately 4.46 millimeters of reduction for GATT and 3.39 millimeters for BAG, or roughly 1.1 millimeters more reduction for GATT.
00:03:53.120 --> 00:03:55.520
The clearest difference was medication use.
00:03:55.759 --> 00:04:05.840
At two years, the GATT group averaged 0.71 medicines down from 2.35, while the Bang group averaged 2.26 down from 2.41.
00:04:06.000 --> 00:04:11.199
That is a reported reduction of 69.78% versus 6.22%.
00:04:11.919 --> 00:04:15.520
11 GATT eyes and two BANG eyes were medication free.
00:04:15.680 --> 00:04:20.639
The trial's complete success measure was stricter than simply reaching a particular pressure.
00:04:20.800 --> 00:04:27.680
An eye needed to be at or below 18 millimeters of mercury, have at least a 20% reduction, and be off medication.
00:04:27.839 --> 00:04:34.480
Qualified success used the same pressure criteria but allowed medication without increasing the number used at baseline.
00:04:34.720 --> 00:04:41.600
At 24 months, the paper reported 55.5% after bang.
00:04:41.920 --> 00:04:47.920
Qualified success was 64.7% versus 13.6% in the article's results text.
00:04:48.079 --> 00:04:50.959
Its abstract gives 11.4% for bang.
00:04:51.360 --> 00:04:54.800
That small inconsistency is worth noting rather than smoothing over.
00:04:54.959 --> 00:05:00.959
Four GAT eyes reached 12 millimeters of mercury or lower, compared with none after bang.
00:05:01.360 --> 00:05:05.120
4 out of 23 randomized GAT eyes is about 17%.
00:05:05.839 --> 00:05:10.079
Four out of 17 GAT eyes completing follow-up is about 24%.
00:05:10.639 --> 00:05:16.319
Those are simple count-based proportions, not a robust estimate of what an individual patient's chance would be.
00:05:16.560 --> 00:05:21.600
The trial's Kaplan Meyer estimates and its raw eye counts use different methods and denominators.
00:05:21.839 --> 00:05:26.160
Two-year pressure, medication, target, and success results.
00:05:26.399 --> 00:05:28.240
Follow-up measurements.
00:05:28.720 --> 00:05:39.839
Patients were scheduled for visits on postoperative days 1, 7, 15, 30, 60, 90, 180, 360, 540, and 720.
00:05:40.000 --> 00:05:46.160
The journal article's searchable main text gives exact average pressures at inclusion and at 12 and 24 months.
00:05:46.319 --> 00:05:50.800
Earlier visit averages were also reported in a conference abstract from the same study.
00:05:51.040 --> 00:05:58.399
The table below shows those available interim values with the peer-reviewed journal article's numbers used for the final 24-month row.
00:05:58.639 --> 00:06:02.720
The conference report and final paper differ slightly in some late values.
00:06:02.959 --> 00:06:04.959
The final paper should take precedence.
00:06:05.120 --> 00:06:09.600
Neither source's summary gives exact day 15 and day 60 averages.
00:06:09.759 --> 00:06:14.480
For the full table, please open this article on VisualFieldTest.com.
00:06:15.199 --> 00:06:20.560
Pressure is in millimeters of mercury, figures after pylas are standard deviations.
00:06:20.720 --> 00:06:27.920
The day 1 through day 540 values come from the conference report, final 24-month values come from the journal article.
00:06:28.240 --> 00:06:31.360
Conference report, final journal article.
00:06:31.600 --> 00:06:37.920
The pressure rise at day 30 in both groups is a reminder that early postoperative readings can fluctuate.
00:06:38.160 --> 00:06:42.160
In this trial, medicines were not restarted until day 30.
00:06:42.399 --> 00:06:50.079
Afterwards, treatment was reintroduced under a specified protocol if pressure remained above 18 at consecutive visits.
00:06:50.319 --> 00:06:58.879
Early and late averages therefore need to be interpreted in light of the medication schedule, not as measurements taken under identical conditions at every visit.
00:06:59.199 --> 00:07:06.079
Trial follow-up and medication protocol, loss to follow-up, additional procedures, and safety.
00:07:06.319 --> 00:07:13.199
By 24 months, 19 of 22 bang eyes and 17 of 23 GATES had completed follow-up.
00:07:13.600 --> 00:07:18.079
Three Bang Eyes left the protocol because they needed additional glaucoma surgery.
00:07:18.240 --> 00:07:20.240
Six GATEs did not complete it.
00:07:20.480 --> 00:07:26.399
Four needed additional surgery, one had a retinal detachment at day 30, and one patient died.
00:07:26.560 --> 00:07:31.040
Seven eyes had a reoperation, three bang eyes and four GATEs.
00:07:31.199 --> 00:07:34.000
All three bang reoperations were bleb needlings.
00:07:34.160 --> 00:07:38.639
In the GAT group, three were needlings, and one was a trabeculectomy.
00:07:38.879 --> 00:07:42.879
The trial reported no statistically significant difference between groups.
00:07:43.120 --> 00:07:52.160
Needling is a procedure to revise an existing filtering bleb, so these events should not be read as seven newly created blebs from the angle operations themselves.
00:07:52.399 --> 00:07:56.319
The study's failure definition included additional glaucoma surgery.
00:07:56.480 --> 00:08:07.600
Follow-up and reoperation results, at least one complication was recorded in 12 bang eyes, 54.5%, and 17 GAT eyes, 73.9%.
00:08:08.639 --> 00:08:18.240
Iris damage was the most common complication during surgery, and transient hyphema, blood in the front chamber of the eye, was the most common early postoperative problem.
00:08:18.399 --> 00:08:21.439
One GAT eye had a total hyphema on day one.
00:08:21.600 --> 00:08:24.240
It cleared within a week without intervention.
00:08:24.480 --> 00:08:31.920
The retinal detachment occurred 30 days after GAT, but one event in a small study cannot establish that the operation caused it.
00:08:32.080 --> 00:08:42.480
The article also reported a bang eye with persistent corneal edema and cystoid macular edema associated with vitreous prolapse and a poorly positioned artificial lens.
00:08:42.639 --> 00:08:47.440
Some eyes in both groups showed notable reductions in corneal endothelial cell counts.
00:08:47.600 --> 00:08:57.679
At two years, average counts were 1,561, 88 cells per square millimeter after GATT and 1,077.56 after bang.
00:08:58.080 --> 00:09:01.279
The difference between groups was not statistically significant.
00:09:01.440 --> 00:09:08.240
At least a 20% reduction occurred in 30.4% of GATT eyes and 22.7% of Bang eyes.
00:09:08.399 --> 00:09:10.799
These small sample findings warrant follow-up.
00:09:11.279 --> 00:09:16.240
No significant difference does not establish that either procedure has no effect on the cornea.
00:09:16.480 --> 00:09:19.120
Complications and endothelial cell results.
00:09:19.360 --> 00:09:22.559
Does opening more degrees produce more pressure reduction?
00:09:23.039 --> 00:09:26.399
Why a 360-degree opening might help?
00:09:26.639 --> 00:09:30.879
The trabecular meshwork is part of the eye's main fluid drainage route.
00:09:31.039 --> 00:09:35.279
In open angle glaucoma, resistance in this pathway is often too high.
00:09:35.519 --> 00:09:43.200
GET opens the meshwork around the full circumference of Schlem's canal, whereas the trials bang procedure treated about 90 degrees.
00:09:43.440 --> 00:09:53.759
A wider opening could help by reducing resistance over a larger area, reaching more of the eye's drainage channels, and providing alternative routes if some regions drain poorly.
00:09:54.000 --> 00:10:03.039
Outflow is uneven around the eye, so a small opening may happen to reach a less useful region, or it may reach a particularly effective one.
00:10:03.279 --> 00:10:07.759
Healing and scarring could also affect how long any opening stays useful.
00:10:07.919 --> 00:10:12.320
These are plausible explanations, not mechanisms proven by this trial.
00:10:12.559 --> 00:10:16.080
Trial discussion of treatment extent and regional drainage.
00:10:16.320 --> 00:10:21.600
The broader evidence does not show a simple more degrees, more pressure drop rule.
00:10:21.840 --> 00:10:39.120
The 2026 trial is consistent with the idea that full circle treatment can outperform a small sectoral procedure, but it cannot separate the effect of 360 degrees from the effect of using a suture-based trabeculotomy rather than a bent needle tissue removal technique.
00:10:39.279 --> 00:10:42.159
Evidence comparing treatment extents is mixed.
00:10:42.320 --> 00:10:53.279
A randomized trial comparing 180 and 360 degree internal suture trabeculotomy did not establish a simple, reliable advantage from treating the full circle.
00:10:53.600 --> 00:11:09.039
Randomized 180 versus 360-degree trial, a multi-center comparison of 120 and 360-degree goniotomy for primary open-angle glaucoma found broadly similar pressure lowering, with hyphema more common after complete treatment.
00:11:09.279 --> 00:11:15.200
This was not the same as randomizing patients to identical operations that differed only in extent.
00:11:15.519 --> 00:11:18.799
Multicenter partial versus complete goniotomy study.
00:11:19.120 --> 00:11:28.480
A 206-eye observational study found similar outcomes after partial 180 or 270-degree GATT and full 360-degree GATT.
00:11:28.639 --> 00:11:35.759
Because treatment allocation was not randomized, it cannot rule out differences in which eyes were selected for each extent.
00:11:36.080 --> 00:11:38.240
Partial versus complete GATT study.
00:11:38.399 --> 00:11:51.440
In juvenile open angle glaucoma, a study of 120, 240, and 360-degree goniotomy found the two wider treatments performed similarly and better than 120 degrees at six months.
00:11:51.919 --> 00:11:56.559
That result may not apply to older adults with primary open angle glaucoma.
00:11:57.039 --> 00:12:06.559
Juvenile Glaucoma Extent Study, a review of angle procedures, similarly describes studies in which sectoral and circumferential treatments achieved comparable results.
00:12:06.799 --> 00:12:14.320
Taken together, the evidence suggests that extent may matter in some settings, but not in a predictable linear dose response.
00:12:14.559 --> 00:12:24.159
The health and location of the downstream drainage channels, the type of glaucoma, the operation used, and the patient's starting pressure all matter.
00:12:24.480 --> 00:12:28.799
Review of evidence on treating versus preserving the trabecular meshwork.
00:12:29.039 --> 00:12:32.799
How effective is GATT compared with other glaucoma treatments?
00:12:32.960 --> 00:12:35.679
The numbers below are not head-to-head rankings.
00:12:35.759 --> 00:12:43.600
The studies vary in baseline pressure, medication washout, cataract surgery, glaucoma type, success definition, and follow-up.
00:12:43.759 --> 00:12:50.720
In particular, a pressure measured while taking medicines is not directly comparable with an unmedicated pressure after washout.
00:12:51.120 --> 00:12:55.600
For the full table, please open this article on visualfieldtest.com.
00:12:55.919 --> 00:12:58.480
What can we say about reaching 15 or 12?
00:12:58.559 --> 00:13:08.080
The GATT trial reported that 29.3% met its additional success definition of pressure at or below 15 plus at least a 20% reduction.
00:13:08.559 --> 00:13:13.600
That is not the same as the probability of simply measuring 15 or lower at one visit.
00:13:13.679 --> 00:13:20.320
The four GATT eyes that reach 12 or lower are a useful signal, but too few to provide a stable estimate.
00:13:20.559 --> 00:13:28.639
Other studies often report pressure at or below 18 percentage reduction or success under their own rules, not the same thresholds.
00:13:28.799 --> 00:13:40.000
For eye stent, hydris, cannilplasty, laser, and other angle procedures, the literature does not provide a consistent, directly comparable probability of reaching 15 or 12.
00:13:40.240 --> 00:13:46.720
A precise league table of those probabilities would imply more comparability than the studies allow.
00:13:47.039 --> 00:13:50.320
Why trabecular procedures have a pressure ceiling?
00:13:50.559 --> 00:13:55.120
The eye's conventional drainage route ends in veins around the outside of the eye.
00:13:55.279 --> 00:14:00.799
The pressure in those episcleral veins is commonly around 8 to 10 millimeters of mercury.
00:14:01.200 --> 00:14:10.159
Removing resistance at the trabecular meshwork can improve flow, but it does not remove resistance farther downstream or the pressure in the receiving veins.
00:14:11.039 --> 00:14:19.120
A simplified pressure-flow relationship therefore predicts a physiological limit for procedures that rely on the eye's natural drainage route.
00:14:19.360 --> 00:14:29.279
Reviews of eye fluid dynamics also describe meaningful resistance beyond the trabecular meshwork, including around Schlem's canal and its collector channels.
00:14:29.840 --> 00:14:31.919
Trabeculectomy works differently.
00:14:32.080 --> 00:14:38.240
It creates a new route that drains fluid outside the usual pathway and can therefore achieve lower pressures.
00:14:38.799 --> 00:14:41.440
Review of aqueous humor dynamics.
00:14:41.919 --> 00:14:46.159
Review of minimally invasive glaucoma surgery and pressure limits.
00:14:46.399 --> 00:14:49.919
The 8 to 10 figure is not a guaranteed GAT floor.
00:14:50.080 --> 00:14:55.039
It is an estimate of the downstream venous pressure, and real eyes have additional resistance.
00:14:55.519 --> 00:15:04.639
A practical expectation after successful GAT is generally a pressure in the mid-teens, with some eyes reaching the low teens, sometimes with medicines.
00:15:04.799 --> 00:15:08.720
A sustained pressure of 12 or lower is possible in a subset.
00:15:08.879 --> 00:15:12.559
A single-digit result from GAT alone is not a dependable goal.
00:15:12.799 --> 00:15:20.799
If advanced or rapidly progressing glaucoma needs a very low target, a filtering operation may be more appropriate despite its greater risks.
00:15:21.039 --> 00:15:22.960
GATT four-year results.
00:15:23.279 --> 00:15:25.679
Physiology of episcleral venous pressure.
00:15:25.919 --> 00:15:28.080
Which patients may do better with GATT.
00:15:28.320 --> 00:15:31.919
Several factors may affect results, but the evidence is uneven.
00:15:32.159 --> 00:15:33.120
Starting pressure.
00:15:33.360 --> 00:15:38.879
A higher starting pressure can allow a larger numerical reduction, but it does not guarantee success.
00:15:39.120 --> 00:15:45.200
In a four-year GATT series, higher baseline pressure was associated with a modestly higher risk of failure.
00:15:45.360 --> 00:15:46.559
For your study.
00:15:47.200 --> 00:15:48.960
Age and disease severity.
00:15:49.120 --> 00:15:54.240
Studies have not consistently agreed on whether age or glaucoma stage predicts success.
00:15:54.480 --> 00:16:03.360
153 eye study found that glaucoma stage did not appear to affect success, while studies in other populations report different risk patterns.
00:16:03.600 --> 00:16:14.159
Prognostic factor study, previous laser lens status, and combined cataract surgery, the randomized trial included only eyes that had already undergone cataract surgery.
00:16:14.320 --> 00:16:21.360
Its results cannot establish whether GAT performs similarly in phic eyes or when combined with cataract surgery.
00:16:21.600 --> 00:16:28.559
The available evidence does not establish previous selective laser trabeculoplasty as a reliable predictor of GATT success.
00:16:28.799 --> 00:16:30.720
Blood reflux and hyphema.
00:16:31.120 --> 00:16:37.600
Blood reflux can indicate communication with the drainage pathway, but it is not a proven guarantee of durable success.
00:16:37.759 --> 00:16:41.039
Mild transient blood is common after trabecular procedures.
00:16:41.279 --> 00:16:46.799
A prognostic study found that postoperative macrohyphema could be associated with poorer success.
00:16:47.039 --> 00:16:48.960
Prognostic factor study.
00:16:50.000 --> 00:16:50.960
Pigmentation.
00:16:51.120 --> 00:16:56.720
Results from this trial do not answer whether heavily pigmented angles change GAT outcomes.
00:16:57.360 --> 00:17:05.039
Pigmentary glaucoma should not be assumed to have the same risk-benefit profile as the trial's primary open angle glaucoma population.
00:17:05.759 --> 00:17:22.640
As a result, a plausible GAT candidate is someone with an open angle, mild to moderate glaucoma, and a target pressure that may be met in the low to mid-teens, particularly if reducing medication burden and preserving the conjunctiva for possible future surgery are priorities.
00:17:22.799 --> 00:17:28.480
It is less reassuring as a sole plan when the optic nerve needs a very low pressure quickly.
00:17:28.720 --> 00:17:31.440
How much confidence should we place in the trial?
00:17:31.680 --> 00:17:32.880
Observed evidence.
00:17:33.119 --> 00:17:40.480
In this randomized comparison, GATT had better two-year average pressure and medication results than 90-degree bang.
00:17:40.880 --> 00:17:50.559
Its pressure advantage was statistically borderline for the overall time by group analysis, p equal.048, while the medication difference was stronger.
00:17:50.720 --> 00:17:54.880
The trial also found more GATT eyes meeting its success definitions.
00:17:55.200 --> 00:17:56.400
Important limits.
00:17:56.559 --> 00:18:00.799
There were only 45 eyes, and both eyes from some patients were included.
00:18:01.039 --> 00:18:09.839
The researchers used statistical models to account for the correlation between a person's two eyes, but the small sample still makes estimates unstable.
00:18:10.079 --> 00:18:17.440
The GATT group also had more non-completions, including four additional surgeries, a retinal detachment, and a death.
00:18:17.680 --> 00:18:23.200
The procedures could not be masked to examiners, and one surgeon performed all operations.
00:18:23.519 --> 00:18:31.680
The authors themselves noted that the sample limited statistical power for medication outcomes, complications, and survival analysis.
00:18:32.000 --> 00:18:33.279
Trial limitations.
00:18:33.519 --> 00:18:37.119
The treatment extent is another limitation for the central question.
00:18:37.359 --> 00:18:44.000
The comparison was 360-degree suture trabeculotomy versus 90-degree bent needle tissue removal.
00:18:44.240 --> 00:18:47.920
It demonstrates a difference between those two treatment packages.
00:18:48.160 --> 00:18:59.279
It does not prove that a 360-degree version of the same needle procedure would outperform a 90-degree version, or that every additional degree lowers pressure further.
00:18:59.519 --> 00:19:03.119
What might happen in a 500-patient randomized trial?
00:19:03.359 --> 00:19:06.720
The following is an inference, not observed evidence.
00:19:06.880 --> 00:19:10.799
It assumes a study of patients similar to the 2026 trial.
00:19:10.960 --> 00:19:17.119
Pseudophagic adults with mild to moderate primary open angle glaucoma and a treated baseline pressure around 20.
00:19:17.359 --> 00:19:23.759
Average two-year pressure after Gayety, roughly 15.5 to 16.5 mm of mercury.
00:19:23.920 --> 00:19:30.319
Medication reduction, roughly 1.1 to 1.5 medicines on average, leaving many patients on zero or one.
00:19:30.799 --> 00:19:34.319
Medication free at 2 years, perhaps 35 to 50%.
00:19:35.119 --> 00:19:38.079
Pressure of 12 or lower, perhaps 10 to 20%.
00:19:38.720 --> 00:19:42.799
A wide range because the original study recorded only four such eyes.
00:19:43.039 --> 00:19:47.359
Additional glaucoma procedure by two years, perhaps 10 to 20%.
00:19:48.000 --> 00:19:53.440
The original study observed seven reoperations among 45 eyes, but several were bleb needlings.
00:19:53.599 --> 00:19:56.240
A larger trial might produce a different mix.
00:19:56.480 --> 00:19:58.400
Likely five-year durability.
00:19:58.640 --> 00:20:07.519
Many eyes would probably retain some pressure-lowering benefit, but pressure control would not mean permanent freedom from medicines or additional surgery.
00:20:08.079 --> 00:20:14.319
Inference from the four-year observational series suggests that failure and reoperation accumulate with time.
00:20:14.559 --> 00:20:21.119
A reasonable cautious expectation is that a substantial minority will need further treatment by five years.
00:20:21.359 --> 00:20:31.200
In a 500-patient trial, I would expect GATT to retain an advantage over 90 degree bang for medication reduction and probably for average pressure.
00:20:31.440 --> 00:20:37.519
I would not expect the very large success rate difference from the small trial to reproduce exactly.
00:20:37.680 --> 00:20:53.599
A likely average pressure difference may be closer to 1 to 2 mm of mercury than a dramatic separation, and the medication-free advantage could be clinically meaningful without making GATT a substitute for trabeculectomy when a very low target is essential.
00:20:53.920 --> 00:20:58.319
How close can GATT get to trabeculectomy without creating a bleb?
00:20:58.720 --> 00:21:05.200
GATT can be an effective way to lower pressure while preserving the eye's conjunctiva and avoiding a filtering bleb.
00:21:05.440 --> 00:21:16.559
In the randomized two-year trial, its average pressure was about 15.4 millimeters of mercury, and nearly half of the randomized eyes were medication-free by the raw count.
00:21:17.599 --> 00:21:26.559
Larger observational studies also commonly report average pressures in the mid-teens, although longer follow-up brings more failures and additional treatment.
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That is a meaningful result for a patient whose target can be met in the low to mid-teens.
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It is not the same as the pressure-lowering capacity of trabeculectomy.
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Because GATT works through the eye's existing drainage channels, episcleral venous pressure and downstream resistance limit how low pressure can reliably go.
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Low teen pressure is plausible for a good responder.
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A stable pressure of 12 or lower is possible, but not assured.
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Single-digit pressure is not a reliable expectation.
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For people with advanced damage, rapid progression, or a target requiring pressure well below the mid-teens, the greater pressure-lowering potential of trabeculectomy may matter more than the appeal of a bleb-free operation.
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The best choice depends on the individual target pressure, disease severity, drainage anatomy, and tolerance for surgical risk, not simply on whether the procedure treats 90 or 360 degrees.
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All links to sources are available in the text version of this article.
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You can find the full article at visualfieldtest.com.
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Thanks for listening.
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