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PRESERFLO vs Trabeculectomy: A New Randomized Trial Tests Which Glaucoma Surgery Really Lowers Pressure Better · Glaucoma, Vision & Longevity: Supplements & Science

• 0:00
  SPEAKER_00: PressorFlow versus trabeculectomy, a new randomized trial, tests which glaucoma surgery really lowers pressure better.
• 0:08
  SPEAKER_00: The new trial reports an important change over time.
• 0:11
  SPEAKER_00: Preserflow had lower pressure early after surgery, while trabeculectomy achieved lower pressure at 3 and 12 months.
• 0:18
  SPEAKER_00: But the published abstract does not provide the exact pressure values or confidence intervals needed to calculate the size of that difference.
• 0:27
  SPEAKER_00: Here's what the study does and does not establish.
• 0:31
  SPEAKER_00: The short answer.
• 0:33
  SPEAKER_00: The new trial supports trabeculectomy as the stronger pressure-lowering choice when the main goal is a very low pressure.
• 0:40
  SPEAKER_00: It does not show how many millimeters of mercury a patient gives up by choosing Preserflow, because its abstract does not provide the arm-by-arm pressure readings needed to calculate that difference.
• 0:51
  SPEAKER_00: Across earlier comparative evidence, the average long-term pressure advantage for trabeculectomy has generally been about 1 to 3 millimeter hergens.
• 1:00
  SPEAKER_00: That difference may matter more when glaucoma is advanced and the target is in the low teens or lower.
• 1:06
  SPEAKER_00: Preserflow remains a reasonable option for some people whose target is less stringent and who value its design and potential reduction in certain postoperative risks.
• 1:17
  SPEAKER_00: But it is still bleb-forming filtration surgery.
• 1:20
  SPEAKER_00: It is not free of scarring, needling, follow-up pop, or late infection risk.
• 1:25
  SPEAKER_00: The new trial was published on September 19, 2026, just five days before this article's date, September 24, 2026.
• 1:33
  SPEAKER_00: It is an accepted early online article that may receive final editorial changes.
• 1:38
  SPEAKER_00: It randomized 99 people, 51 to Preserflow microshunt with mitomycin C, and 48 to trabeculectomy with mitomycin C.
• 1:47
  SPEAKER_00: The abstract reports lower early pressure with Preserflo and lower pressure with trabeculectomy at 3 and 12 months.
• 1:54
  SPEAKER_00: What the new randomized trial did, who was studied, and what we can verify.
• 1:59
  SPEAKER_00: The study included adults with primary open angle coma, CoAG, or pseudoexfoliation glaucoma, XG, whose disease was progressing despite maximum tolerated treatment.
• 2:10
  SPEAKER_00: Eligibility required worsening visual field results and pressure remaining above the patient's target, despite topical and oral medicines.
• 2:19
  SPEAKER_00: The study was conducted at one center in Poland with recruitment from April 2023 to October 2024 and 12 months of follow-up.
• 2:28
  SPEAKER_00: Some details requested by patients, including the exact numbers of POAG versus PEXG participants, the distribution of glaucoma severity, mean baseline pressure, average number of baseline medications, and the numerical target pressure, are not included in the searchable abstract and methods text available for this review.
• 2:48
  SPEAKER_00: The full paper may contain additional figures or tables, but those values are not reproduced here, rather than guessed.
• 2:56
  SPEAKER_00: The study says that disease progression was assessed with visual fields, but that alone does not establish how many participants had mild, moderate, or advanced damage.
• 3:06
  SPEAKER_00: How surgery and randomization were handled.
• 3:09
  SPEAKER_00: The researchers used folded allocation slips to assign patients in a one-to-one ratio immediately before surgery.
• 3:17
  SPEAKER_00: The slips were prepared by an investigator who did not enroll participants.
• 3:21
  SPEAKER_00: There was no blocking or stratification, and neither surgeons nor participants could be blinded.
• 3:27
  SPEAKER_00: Outcome assessors were not formally blinded either.
• 3:30
  SPEAKER_00: The study was registered after recruitment had begun.
• 3:33
  SPEAKER_00: The paper says registration occurred on March 16, 2026, after enrollment ended in October 2024.
• 3:41
  SPEAKER_00: The authors say the protocol and analysis plan had been set before recruitment.
• 3:45
  SPEAKER_00: Retrospective registration and unblinded assessment do not invalidate the findings, but they are reasons to interpret a small single-center trial cautiously.
• 3:55
  SPEAKER_00: A single experienced surgeon performed the procedures.
• 3:58
  SPEAKER_00: Mitomycin C, MMC, was applied with sponges for two minutes at either 0.2 mg per milliliter or 0.4 mg per milliford, with the concentration chosen by the surgeon based on anticipated scarring risk.
• 4:11
  SPEAKER_00: In the trabeculectomy group, the surgeon created a scleral flap, used a Kelly punch, and secured the flap with four nylon sutures.
• 4:19
  SPEAKER_00: In the Preserflo group, no intraluminal stent or ripcord was used.
• 4:23
  SPEAKER_00: Cataract surgery was combined with filtration surgery in 37 of 51 preserflo cases and 33 of 48 trabeculectomy cases.
• 4:32
  SPEAKER_00: Patients continued their glaucoma medicines through the day of surgery.
• 4:36
  SPEAKER_00: There was no medication washout.
• 4:39
  SPEAKER_00: The study used antibiotic and steroid treatment after surgery.
• 4:43
  SPEAKER_00: Both procedures still require postoperative assessment of pressure and the filtering bleb.
• 4:48
  SPEAKER_00: The exact medication adjustment and visit schedule is not available in the abstracted text.
• 4:54
  SPEAKER_00: Pressure results.
• 4:55
  SPEAKER_00: What is known and what is not.
• 4:57
  SPEAKER_00: The published abstract reports the direction of the result, but not the exact mean pressures, standard deviations, confidence intervals, or between group effects sizes for each visit.
• 5:09
  SPEAKER_00: The table below separates what the abstract says from numbers that cannot be verified from it.
• 5:15
  SPEAKER_00: For the full table, please open this article on VisualFieldTest.com.
• 5:20
  SPEAKER_00: These are reporting limits of the abstracted information, not evidence that the full paper contains no numerical table.
• 5:26
  SPEAKER_00: Without ARM-specific baseline and follow-up means, and their variability, it is not possible to calculate reliable absolute reductions, percentage reductions, confidence intervals, or a standardized effect size for this 99-person trial.
• 5:42
  SPEAKER_00: Nor is it possible to infer how many individuals crossed a particular pressure threshold from a group average.
• 5:49
  SPEAKER_00: How large is the pressure difference in the broader evidence?
• 5:52
  SPEAKER_00: The new study fits a pattern already seen in comparative research.
• 5:56
  SPEAKER_00: A 2025 meta-analysis of 10 comparative studies found that trabeculectomy achieved a mean pressure, pressure about 1.59 millimicores lower than preservalo, and a larger pressure reduction from baseline.
• 6:09
  SPEAKER_00: A later meta-analysis covering 14 studies in 2,229 patients estimated that pressure after preserv was 1.4 millimeter grams higher than after trabeculectomy, 95% confidence interval, 0.64 to 2.24 millimeters grams.
• 6:25
  SPEAKER_00: Pressure reduction was 2.73 millimeter grams smaller with preserflow, 95% confidence interval, 1.61 to 3.84 mm grams smaller.
• 6:35
  SPEAKER_00: These pooled results had moderate to high variation between studies and largely reflect follow-up of up to two years, not a guaranteed difference for an individual patient.
• 6:44
  SPEAKER_00: The largest earlier randomized comparison enrolled 527 people with POAC, 395 received preserflow, and 132 trabeculectomy.
• 6:54
  SPEAKER_00: At one year, reported mean pressure reductions were 29.1% with preserflow and 45.4% with trabeculectomy.
• 7:03
  SPEAKER_00: Surgical success, defined in that trial as at least a 20% reduction from baseline without increasing medicines, was also lower in the Preserflow group at one year.
• 7:13
  SPEAKER_00: This was a different trial with different participants and methods, so its figures should not be substituted for the new trial's missing values.
• 7:21
  SPEAKER_00: Bottom line on pressure.
• 7:23
  SPEAKER_00: The comparative evidence generally favors trabeculectomy for achieving the lowest pressure.
• 7:28
  SPEAKER_00: The best pooled estimate is a difference of roughly 1 to 2 mm grams in postoperative pressure, with some studies showing a larger gap.
• 7:36
  SPEAKER_00: The new randomized trial adds support to that direction, but the abstract alone does not tell us the trial's exact difference.
• 7:44
  SPEAKER_00: Why the early result could reverse.
• 7:46
  SPEAKER_00: Mechanistic explanation.
• 7:48
  SPEAKER_00: Inference, not a finding proven by the trial.
• 7:51
  SPEAKER_00: Pressor flow is an 8.5mm tube with a 70 micrometer lumen.
• 7:56
  SPEAKER_00: That lumen creates resistance to fluid flow and is intended to reduce excessive early drainage.
• 8:01
  SPEAKER_00: Trabeculectomy instead makes an opening beneath a surgically fashioned scleral flap, which the surgeon can adjust using sutures.
• 8:10
  SPEAKER_00: Those sutures can sometimes be loosened or cut with laser after surgery.
• 8:14
  SPEAKER_00: The two operations therefore manage early flow differently.
• 8:18
  SPEAKER_00: A lower pressure immediately after presurflow surgery does not necessarily mean it will maintain a lower pressure later.
• 8:26
  SPEAKER_00: As healing proceeds, scarring around the tube outlet or within the bleb can restrict drainage.
• 8:31
  SPEAKER_00: A trabeculectomy may, by contrast, be adjusted after surgery to improve filtration.
• 8:38
  SPEAKER_00: The main trial's findings are consistent with these possible explanations, but they do not prove that the tube's fixed lumen or bleb scarring caused the reversal.
• 8:47
  SPEAKER_00: Differences in postoperative adjustment, steroid treatment, healing, or the cataract operations performed alongside filtration surgery could also contribute.
• 8:57
  SPEAKER_00: The trial did not use a presurflow intraluminal stent, and it used MMC at the surgeon's choice of two concentrations.
• 9:04
  SPEAKER_00: Because the dose varied, any claim that the results demonstrate a single optimal MMC exposure or that MMC explains the reversal would go beyond the reported evidence.
• 9:15
  SPEAKER_00: Complete and qualified success.
• 9:18
  SPEAKER_00: Useful, but not enough on its own.
• 9:20
  SPEAKER_00: Complete success usually means reaching a specified pressure target without glaucoma medicines.
• 9:25
  SPEAKER_00: Qualified success means reaching the target with medicines permitted.
• 9:29
  SPEAKER_00: These labels are only meaningful when the pressure cutoff, required percentage reduction, and rules for further surgery are clear.
• 9:37
  SPEAKER_00: For the new trial, the abstract says complete success at six months was significantly higher after trabeculectomy and that qualified success was comparable between groups over follow-up.
• 9:50
  SPEAKER_00: It does not give the exact percentages or the pressure thresholds behind those results.
• 9:55
  SPEAKER_00: So it cannot answer from the abstract alone how many patients were medication-free at a target of 18, at a 15, 12, or 10 mmHH gram.
• 10:05
  SPEAKER_00: Those four thresholds cannot be reliably estimated from a mean pressure.
• 10:09
  SPEAKER_00: For example, a mean of 13 mmHg could represent nearly everyone clustered around 13 or a mix of very low and substantially higher readings.
• 10:19
  SPEAKER_00: Patient-level data, or reported proportions at each threshold, are needed.
• 10:23
  SPEAKER_00: The new trials abstract does not provide either.
• 10:26
  SPEAKER_00: Longer-term pressor flow only data illustrate why thresholds matter.
• 10:30
  SPEAKER_00: In a 66i five-year cohort, complete success at 15mm hergregs without medicines was estimated at 61% after one year and 35% after 5 years.
• 10:41
  SPEAKER_00: Qualified success at 18 mmherzgrebs was 82% at one year and 70% at 5 years.
• 10:47
  SPEAKER_00: This was not a comparison with trabeculectomy, and its estimates should not be treated as the success rates for every clinic or patient.
• 10:56
  SPEAKER_00: Complications and post-operative burden.
• 10:59
  SPEAKER_00: The new trials abstract reports no statistically significant overall difference in complication rates between procedures, and no significant overall difference in medication use.
• 11:10
  SPEAKER_00: That is useful, but it does not prove that the procedures have identical safety.
• 11:14
  SPEAKER_00: With 99 participants and one year of follow-up, the trial is too small and short to reliably distinguish uncommon complications such as bleb infection or severe vision loss.
• 11:25
  SPEAKER_00: The abstract does not provide verified individual event counts for hypotony, choroidal detachment, shallow anterior chamber, hyphema, leakage, infection, needling, revision, cataract, or endothelial change.
• 11:39
  SPEAKER_00: For the full table, please open this article on VisualFieldTest.com.
• 11:42
  SPEAKER_00: The safety trade-off is therefore more nuanced than Preserflow lowers pressure less but is much safer.
• 11:49
  SPEAKER_00: The large randomized trial and pooled reviews support a lower hypoteny burden with Preserflow in some settings, while newer meta-analysis also found fewer overall postoperative complications.
• 12:01
  SPEAKER_00: But those advantages are not identical in every study, and they do not mean less postoperative care is guaranteed.
• 12:08
  SPEAKER_00: In one comparative cohort, needling was common after both operations.
• 12:13
  SPEAKER_00: What the ASOCT bleb findings may mean.
• 12:16
  SPEAKER_00: The new trial used anterior segment optical coherence tomography, ASOT, to inspect the bleb, the fluid collecting area beneath the conjunctiva.
• 12:25
  SPEAKER_00: At trabeculectomy blebs, investigators measured the height of the whole bleb and the length and height of its fluid cavity.
• 12:32
  SPEAKER_00: At presurflobs, they assessed features such as layers, microcysts, the subconjunctival space, and whether the structure looked uniform or varied.
• 12:41
  SPEAKER_00: Measurements were made at 3, 6, and 12 months.
• 12:45
  SPEAKER_00: The study reports that bleb morphology measures were negatively correlated with pressure after trabeculectomy, but the same relationship was not found in the same way after preserflow.
• 12:56
  SPEAKER_00: In plain language, the shape and size of the trabeculectomy bleb seemed more closely linked to pressure, while the visible measures used in this study did not predict pressure as clearly after preserflow.
• 13:08
  SPEAKER_00: What this may suggest?
• 13:10
  SPEAKER_00: Inference.
• 13:10
  SPEAKER_00: Trabeculectomy's flap and opening system may make bleb characteristics a more direct clue to how much fluid is draining.
• 13:17
  SPEAKER_00: With Preserflow, drainage may depend on a combination of tube resistance and tissue around the outlet, so the measured surface appearance may not tell the whole story.
• 13:28
  SPEAKER_00: But this is not a diagnostic rule.
• 13:31
  SPEAKER_00: The blebs were assessed using different structural measures, and one evaluator analyzed the images.
• 13:37
  SPEAKER_00: A correlation in one group and not the other does not by itself prove that the procedures work through entirely different biological pathways.
• 13:47
  SPEAKER_00: What earlier studies add and what they cannot tell us.
• 13:51
  SPEAKER_00: Evidence before the September 2026 trial was mixed in details but generally consistent about the pressure trade-off.
• 13:58
  SPEAKER_00: The large randomized trial found lower one-year success with Preserflow under its specific success definition, with greater pressure reduction after trabeculectomy.
• 14:08
  SPEAKER_00: Smaller comparative studies sometimes found similar outcomes, particularly in carefully selected patients, but they were not all randomized and often had small samples or short follow-up.
• 14:20
  SPEAKER_00: One matched study reported one-year median diurnal pressures of 10.5 mm with preserve flow and 11.1 mm with trabeculectomy.
• 14:29
  SPEAKER_00: It did not find a statistically significant difference in the pressure reduction.
• 14:34
  SPEAKER_00: A meta-analysis using studies available through January 2024 found a 1.59 mmhergrams postoperative pressure advantage for trabeculectomy and a larger pressure reduction while finding no clear difference in complete or qualified success.
• 14:50
  SPEAKER_00: A newer meta-analysis, which searched through December 2025 and therefore could not include the September 2026 trial, estimated 1.4 mmHg higher pressure after preserflow.
• 15:03
  SPEAKER_00: It also found similar pooled success rates, fewer overall complications with preservlow, and lower odds of hypoteny maculopathy.
• 15:11
  SPEAKER_00: In a five-year preserflow only cohort, pressure remained in the low teens on average, but medication-free success at the stricter 15mm her eggs target declined over time.
• 15:22
  SPEAKER_00: The cohort did not compare Preserflow with trabeculectomy, so it cannot establish the long-term difference between the two operations.
• 15:30
  SPEAKER_00: A separate real-world series of 1001 eyes reported a mean pressure of 13.2 mmHgg at one year and 13.9 mmHg at six years after Preserflow.
• 15:41
  SPEAKER_00: It is encouraging durability evidence, but it is a single-center observational series, not a head-to-head trial.
• 15:48
  SPEAKER_00: A five-year extension of the large randomized trial adds long-term safety follow-up, but only 279 of 493 people completing the original two-year trial joined the extension.
• 16:00
  SPEAKER_00: The extension was observational and descriptive, not a new randomized efficacy comparison.
• 16:05
  SPEAKER_00: It is therefore useful for safety context, but it does not provide a clean five-year randomized answer to which procedure maintains lower pressure.
• 16:14
  SPEAKER_00: Does 12 versus 14 millimeter Herg matter?
• 16:17
  SPEAKER_00: It can, particularly when glaucoma is advanced, but a group average difference is not a promise about an individual's vision.
• 16:25
  SPEAKER_00: In the early manifest glaucoma trial, each 1 mm Herg's lower pressure was associated with about a 10% lower risk of progression in the study analysis.
• 16:34
  SPEAKER_00: That is a population-level relationship, not a personal prediction, and not proof that choosing one operation over another will reduce a specific patient's risk by exactly that amount.
• 16:46
  SPEAKER_00: The treatment of advanced glaucoma study found that trabeculectomy lowered pressure more than medical treatment in newly diagnosed advanced glaucoma, about 12.4 versus 15.1 millimeter hergrangs at five years, and that visual field progression was slower after surgery.
• 17:04
  SPEAKER_00: This was not a presurflow versus trabeculectomy trial, but it supports the importance of strong pressure control in advanced disease.
• 17:12
  SPEAKER_00: A 1-3 mmHg difference may be less consequential for someone whose disease is mild and stable with a target under 18 mm than for someone with advanced damage, documented progression at low pressures, or a target near 10 to 12 mmHg.
• 17:29
  SPEAKER_00: Target pressure must be personalized using the extent and location of damage, rate of change, life expectancy, other risk factors, and the eye's response to treatment.
• 17:39
  SPEAKER_00: A patient-centered decision matrix.
• 17:41
  SPEAKER_00: For the full table, please open this article on VisualFieldtest.com.
• 17:46
  SPEAKER_00: This matrix is a way to structure a conversation, not a substitute for an examination.
• 17:51
  SPEAKER_00: In particular, evidence from the new trial may not apply to a patient with prior glaucoma surgery, significant conjunctival scarring, or a very different pressure target.
• 18:01
  SPEAKER_00: Reasonable outcome estimates with important limits.
• 18:05
  SPEAKER_00: These are evidence-informed ranges, not predictions from the new randomized trial.
• 18:10
  SPEAKER_00: Pressure at one year.
• 18:11
  SPEAKER_00: Across Perserflow studies, low-teen pressure is common, with results affected by starting pressure, whether cataract surgery was combined, scarring, and postoperative care.
• 18:21
  SPEAKER_00: Comparative meta-analyses suggest trabeculectomy averages roughly 1 to 2 mm lower.
• 18:27
  SPEAKER_00: The new trial's exact one-year means are not stated in its abstract.
• 18:31
  SPEAKER_00: Pressure at 3 to 5 years.
• 18:33
  SPEAKER_00: Preserflow only studies report sustained low-teen average pressure, but there is not a robust long-term randomized comparison establishing the precise 3 to 5 year gap between preserflow and trabeculectomy.
• 18:46
  SPEAKER_00: Any claim that the new trial proves a long-term 1 to 3 mm-ang difference would overstate its 12-month follow-up.
• 18:54
  SPEAKER_00: Medication-free success?
• 18:56
  SPEAKER_00: This depends strongly on the pressure cutoff.
• 18:58
  SPEAKER_00: In one five-year preserflow cohort, success at tocid 15mm hergrams without medication declined from 61% at year 1 to 35% at year 5.
• 19:08
  SPEAKER_00: Those results are not a direct comparison with trabeculectomy and may not generalize to every setting.
• 19:15
  SPEAKER_00: Needling or revision.
• 19:16
  SPEAKER_00: Rates vary by surgical technique, follow-up, and definition.
• 19:20
  SPEAKER_00: A comparative cohort reported needling in roughly one-quarter to one-third of eyes in both groups.
• 19:26
  SPEAKER_00: That range is not an estimate for the new trial, whose abstract does not state needling rates.
• 19:32
  SPEAKER_00: Additional glaucoma surgery.
• 19:34
  SPEAKER_00: Estimates vary substantially across cohorts.
• 19:36
  SPEAKER_00: A large real-world Presurflow series reported secondary glaucoma surgery in fewer than 4%, while another five-year cohort reported that 29% had an additional pressure lowering procedure.
• 19:48
  SPEAKER_00: The difference likely reflects different populations, follow-up, and definitions, not a single reliable universal risk.
• 19:57
  SPEAKER_00: Conclusion.
• 19:58
  SPEAKER_00: The September 2026 randomized trial strengthens the case that trabeculectomy can achieve lower pressure later after surgery, even though Pursurflow had the better early pressure result.
• 20:09
  SPEAKER_00: But the abstract does not provide enough numerical detail to calculate the new trial's exact pressure difference, confidence intervals, or success rates at 18, 15, to 12, and Tor 10 millimeter hergrams.
• 20:23
  SPEAKER_00: The wider comparative evidence puts the average pressure trade-off at about 1 to 2 mm hergrams, sometimes approaching 3 mm hergrams, in favor of trabeculectomy.
• 20:33
  SPEAKER_00: Presurflow may offer a preferable balance for some patients, especially when a somewhat higher target is acceptable, or hypotony risk is a major concern.
• 20:42
  SPEAKER_00: But it is not automatically safer, simpler to manage, or free of blood-related complications.
• 20:47
  SPEAKER_00: The right comparison is not invasive versus minimally invasive.
• 20:51
  SPEAKER_00: It is the pressure a particular eye needs, the risks it can accept, and the follow-up the patient and surgeon can manage.
• 20:58
  SPEAKER_00: If the main goal is the lowest possible IOP, what does the evidence say?
• 21:03
  SPEAKER_00: The evidence generally favors trabeculectomy.
• 21:06
  SPEAKER_00: Across comparative studies and meta-analyses, it tends to produce about 1 to 3 millimeter hergrams lower pressure than Preserflow over the studied follow-up periods.
• 21:16
  SPEAKER_00: That difference can be important when glaucoma is advanced or the target is in the low teens.
• 21:21
  SPEAKER_00: The trade-off is that trabeculectomy can involve more pressure-related adjustment and carries meaningful risks such as hypotany and bleb complications.
• 21:32
  SPEAKER_00: Preserflow can still be a sensible choice when the target is less demanding and its potential safety profile fits the patient's priorities.
• 21:40
  SPEAKER_00: But it should not be chosen on the assumption that less invasive necessarily means safer or easier after surgery.
• 21:48
  SPEAKER_00: For a patient who needs the lowest possible pressure, trabeculectomy remains the more evidence-supported option, provided the surgeon believes the expected benefit outweighs the individual risks.
• 22:00
  SPEAKER_00: All links to sources are available in the text version of this article.
• 22:04
  SPEAKER_00: You can find the full article at visualfieldtest.com.
• 22:08
  SPEAKER_00: Thanks for listening.
• 22:09
  SPEAKER_00: To check your visual field, click the link at the bottom of this article or visit visualfieldtest.com.