Comparison of successful outcome predictors for MicroPulse® laser trabeculoplasty and selective laser trabeculoplasty at 6 months

Outcomes of Micropulse Laser Trabeculoplasty Compared to Selective Laser Trabeculoplasty: A Systematic Review and Meta-Analysis

Purpose

To perform a meta-analysis and systematic review to compare the efficacy and complications of micropulse laser trabeculoplasty (MLT) and selective laser trabeculoplasty (SLT) in adult patients with open-angle glaucoma (OAG) and ocular hypertension (OHT).

Methods

We performed a systematic review utilizing PubMed, Embase, and Scopus, on April 8, 2024. Meta-analyses were performed for the mean change in intraocular pressure (IOP) at one-month, six-month, and one-year follow-up visits, rate of IOP spikes (>5 mmHg increase from the pre-procedure baseline IOP), rate of treatment failure (<20% or <3 mmHg reduction in IOP or requiring additional medications or procedures), and mean change in number of medications.

Results

Six studies, with a total of 593 eyes, were included: 283 underwent MLT, while 310 underwent SLT. A statistically significant difference in the efficacy of MLT versus SLT at one-month and six-month follow-ups was present, with SLT reducing IOP by 0.83 mmHg (95% CI: 0.20, 1.47; P = 0.01) more and 0.55 mmHg (95% CI: 0.02, 1.08; P = 0.04) more than MLT, respectively. At the one-year follow-up, there was no significant disparity in IOP reduction between SLT and MLT (WMD = 0.16; 95% CI: -0.40, 0.71; P = 0.58). There was a significantly lower rate of IOP spikes in the MLT treatment group (RR = 0.37; 95% CI: 0.16, 0.89; P = 0.03). There was no statistically significant difference in the rate of treatment failures (RR = 1.05; 95% CI: 0.68, 1.62; P = 0.84) or number of topical medications reduced (WMD = 0.06; 95% CI: -0.13, 0.26; P = 0.53).

Conclusion

While SLT may offer greater short-term reductions in IOP, it may be associated with more postoperative IOP spikes when compared to MLT. At one-year follow-up, there were no significant differences in IOP reduction or failure rates between the MLT and SLT groups.

Selective laser trabeculoplasty versus micropulse laser trabeculoplasty for intraocular pressure control in patients with primary open angle glaucoma: a 12-month retrospective comparative study

This study was designed to compare the efficacy of selective laser trabeculoplasty (SLT) and micropulse laser trabeculoplasty (MLT) in patients with primary open angle glaucoma (POAG) requiring additional IOP control. In this retrospective, comparative study, we reviewed the charts of POAG patients requiring additional IOP lowering, who underwent either SLT or MLT and were followed for at least one year. We evaluated mean intraocular pressure (IOP), mean IOP reduction from baseline and mean number of glaucoma medications 1, 3, 6 and 12 months after treatment. Success rates (success defined as IOP ≤ 21 mmHg and ≥ 20% reduction from baseline IOP without additional medications, new laser session, or glaucoma surgery) at one year were also compared. A total of 98 POAG patients were included, 52 individuals in the SLT group and 46 in the MLT group. Laser treatment resulted in significant mean IOP reductions from baseline in both groups (SLT = -6.0 ± 3.3 mmHg (24.9%) and MLT = -5.8 ± 2.6 mmHg (23.4%)) (p < 0.001). However, there was no statistically significant difference between the mean IOP reductions in both groups (p = 0.74). At 12 months, the mean number of glaucoma medications was significantly smaller in the SLT group (1.17 + 0.4) when compared to the MLT group (2.21 + 0.2) (p = 0.001). Additionally, after 12 months, success was obtained in 32 (61.5%) SLT cases compared to 27 (58.7%) MLT-treated eyes (p = 1.0). MLT and SLT are both effective in controlling the IOP in POAG patients requiring additional IOP reduction. However, after 12 months, SLT demonstrated a greater efficacy in reducing medication burden when compared to MLT.Trial registration: CEP/CONEP/MS Brazil 40948620.9.0000.5600.

Micropulse Laser Trabeculoplasty with 577 nm Wavelength at 1500 or 1000 mW for Primary Open-Angle Glaucoma: A Pilot Study

Aim: To investigate the efficacy and safety of micropulse laser trabeculoplasty (MLT) using a 577 nm yellow wavelength laser randomly assigned to either 1500 or 1000 mW in patients with primary open-angle glaucoma (POAG). Methods: A prospective, double-blinded study of POAG patients was performed in a single center. MLT treatment included a 577 nm micropulse laser (IRIDEX IQ 577^TM, IRIDEX, Mountain View, CA, USA) to 360° of the trabecular meshwork at randomly assigned varying powers: 1500 mW in one eye (MLT 1500 group) and 1000 mW in the other (MLT 1000 group). Best-corrected visual acuity (BCVA), intraocular pressure (IOP), corneal central thickness (CCT), and endothelial cell count (ECC) were evaluated at baseline (T0), post-operative 1 h (T1), 24 h (T2), 1 month (T3), 3 months (T4), and 6 months (T5) after laser treatment. Topical medications were assessed pre-treatment and at T4. Results: Among the 18 eyes included, we achieved a success rate (IOP reduced > 20%) in 77% of sampled eyes. In particular, IOP reduced at T2 and T3 with both MLT 1500 and 1000 without any significant differences (IOP reduction 22.9% vs. 17.3%, respectively, MLT1500 vs. MLT1000 at T2). The IOP returned to baseline values at T4 and T5 in both groups, with a reduction in topical medications administered from 2.5 ± 1.1 to 2.0 ± 1.2 to the 1500 mW group and from 2.4 ± 1.0 to 1.9 ± 1.0 to the 1000 mW group. At 1 h post-laser treatment, a transient IOP spike was registered among the MLT1500 group. There were no differences in CCT and ECC at any timepoint according to the laser powers. Conclusions: Over a 6-month follow-up period, 577 nm MLT at either 1500 or 1000 mW reduces IOP, enabling a stable reduction in the number of topical medications required for patients treated for POAG without any significant difference in terms of effectiveness and safety.

Comparison of success rate and intraocular pressure spikes between selective laser trabeculoplasty and micropulse laser trabeculoplasty in African American and Hispanic patients

AIM

To examine the efficacy and safety of micropulse laser trabeculoplasty (MLT) versus selective laser trabeculoplasty (SLT) in a large cohort of primarily African American and Hispanic patients.

METHODS

A single center retrospective comparative cohort review conducted at Cook County Health facilities that included patients with a diagnosis of open angle glaucoma or ocular hypertension who received an SLT or MLT procedure between January 2017 and May 2021.

RESULTS

Totally 131 eyes of 99 patients were analyzed. The 77 eyes received SLT and 54 received MLT. Seven out of 77 eyes in the SLT group (9.1%) and 1 out of 54 eyes in the MLT group (1.9%) had an IOP spike (defined as > 5 mm Hg) at either 1h or 1wk after procedure (P=0.05, Chi-squared test with Haldane-Anscombe correction). The procedure failure rate at one year was 50% for SLT and 48% for MLT (P=0.31).

CONCLUSION

MLT has a significantly lower incidence of pressure spikes and a similar treatment failure rate at 1-year post-procedure, demonstrating that it is a reasonable alternative compared to SLT.

Advanced glaucoma. Clinical practice guideline

OBJECTIVE

To present an update clinical practice guideline that serve as a guide for the detection, evaluation and treatment of adults patients with advanced glaucoma.

METHODS

After defining the objectives and scope of the guide, the working group was formed and structured clinical questions were formulated following the PICO (Patient, Intervention, Comparison, Outcomes) format. Once all the existing clinical evidence had been independently evaluated with the AMSTAR 2 (Assessment of Multiple systematic Rewiews) and Cochrane "Risk of bias" tools by at least two reviewers, recommendations were formulated following the Scottish Intercollegiate methodology. Guideline Network (SIGN).

RESULTS

Recommendations with their corresponding levels of evidence that may be useful in the diagnosis, monitoring and treatment of adults patients with advanced glaucoma.

CONCLUSIONS

Despite the fact that for many of the questions the level of scientific evidence available is not very high, this clinical practice guideline offers an updated review of the different existing aspects related to the evaluation and management of advanced glaucoma.

Effect of pigmentation intensity of trabecular meshwork cells on mechanisms of micropulse laser trabeculoplasty

The intraocular pressure (IOP)-lowering mechanisms of micropulse laser trabeculoplasty (MLT) remain unclear. The present study was performed to investigate the mechanism of action of MLT, and to determine whether the pigmentation intensity of trabecular meshwork (TM) cells is associated with the treatment effects. Primary human TM cells were exposed to melanin granules to artificially introduce different levels of pigmentation. Micropulse (MP) laser irradiation was performed, and interleukin (IL)-1α/β, matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinases (TIMPs), and extracellular matrix (ECM) protein expression were evaluated by RT-qPCR and immunocytochemistry. IL-1α/β and MMP-1, -3, and -9 mRNA expression were significantly upregulated at 4 and 24 h after MP laser irradiation, respectively, but there were no significant changes in TIMP expression. The extent of these upregulation was greater in cells with strong pigmentation intensity. Protein expressions of fibronectin and collagen I were significantly decreased in cells with strong staining intensity. These results suggested that MP laser irradiation alter the MMP/TIMP ratio and enhance ECM turnover, resulting in increased outflow of aqueous humor. The pigmentation intensity of the TM tissues may affect the treatment efficacy of MLT, because TM cells with strong staining intensity showed a significantly enhanced response to MP laser irradiation.

Micropulse laser trabeculoplasty on Chinese patients with glaucoma or ocular hypertension: average 35 months follow-up results

Background

Glaucoma is a group of eye diseases that can damage the optic nerve and cause vision loss. A novel technology micropulse laser trabeculoplasty (MLT) can use duty-circle subvisible laser pulses to treat glaucoma. The aim of this study is to evaluate the efficacy of 360° MLT to alleviate intraocular pressure (IOP) in patients with glaucoma.

Methods

This was a single-center prospective study on patients treated with 360° MLT using a Diode True-Yellow 577-nm Laser with MicroPulse technology. All the patients were recruited from the Department of Ophthalmology. Follow-up visits were carried out at 1 day, 1 week, 1 month, 3 months, 6 months, 18 months, and 36 months after the procedure. Best-corrected visual acuity (BCVA), Intraocular pressure (IOP), and vertical cup-to-disc ratio (C/D ratio) were measured during the follow-up. Repeated-measures analysis of variance (ANOVA) and Kaplan–Meier analysis were performed to evaluate the outcomes.

Results

A total of 39 eyes from 25 patients were included in this study (10 men/15 women). The average age of patients was 41.47 ± 14.39 years old, and the baseline IOP was 21.13 ± 7.75 mmHg. MLT significantly reduced the IOP at 1 day (range 15.61–19.01, P = 0.0218), 3 months (range 16.47–19.22, P = 0.0390), and 6 months (range 15.38–18.56, P = 0.0332) compared with the baseline. However, by the end of the study, only 21.88% of patients demonstrated a ≥ 20% IOP reduction, while seven eyes needed further laser or surgical treatment. The IOP of glaucoma patients was significantly lower than the ocular hypertension patients at 1 month (P = 0.0124), 3 months (P = 0.0004), 18 months (P = 0.0061) and 36 months (P = 0.0119).

Conclusions

Micropulse laser trabeculoplasty reduce IOP in patients with glaucoma or ocular hypertension for a short period, but its lowering efficiency is limited up to 6 months of the follow-up period.

Long-term results of micropulse laser trabeculoplasty with 577-nm yellow wavelength in patients with uncontrolled primary open-angle glaucoma and pseudoexfoliation glaucoma

Our aim was to evaluate the long-term results of micropulse laser trabeculoplasty (MLT) with 577-nm yellow wavelength in the treatment of glaucoma. We reviewed the medical records of 51 patients (51 eyes) with uncontrolled primary open-angle glaucoma or pseudoexfoliation glaucoma who underwent 180° MLT for the first time. The success of MLT was defined as an IOP reduction of ≥ 20% and IOP < 21 mmHg after treatment. If the number of medications was increased or further laser trabeculoplasty or glaucoma surgery was required after treatment, the case was considered unsuccessful. The mean duration of patient follow-up was 18.39 ± 12.17 months (range 3-52 months). Patients included in the study used 2-4 types of antiglaucoma eye drops (mean 3.43 ± 0.7). The mean number of MLT spots was 65.54 ± 6.19, and the mean energy level was 750.98 ± 101.73 mJ. The decrease in intraocular pressure compared to baseline measurements was: 16.72 ± 11.87%, 15.07 ± 13.76%, 12.63 ± 14.29%, 16.66 ± 19.32%, and 16.75 ± 19.78% during follow-up at 3, 6, 12, 24, and 36-48 months. Successful response was achieved in 35.41%, 36.95%, 34.21%, 40%, 41.17%, and 42.85% of patients during 3, 6, 12, 18, 24, and 36-48 months of follow-ups, respectively. Of the 51 eyes studied, 12 patients (23.5%) underwent post-MLT glaucoma surgery, and 7 patients (13.7%) had cataract surgery, whose follow-up data were subsequently censored. The reduction of intraocular pressure showed a significant correlation with baseline intraocular pressure, while age and laser power showed no correlation (p > 0.05). MLT is a novel treatment option for patients with glaucoma with favorable long-term outcomes and a good safety profile.

Spotlight on MicroPulse Laser Trabeculoplasty in Open-Angle Glaucoma: What’s on? A Review of the Literature

Glaucoma is the most common cause of permanent blindness in the world, caused by a progressive optic neuropathy. Patients with glaucoma are often treated with topical medicines therapy in order to reduce intra-ocular pressure (IOP). On the other hand, laser therapies, with the introduction of Argon Laser Trabeculoplasty (ALT) and successively with Selective Laser Trabeculoplasty (SLT), were reported to be effective in IOP control, with low adverse effect rates. In recent years, the micropulse laser, a subthreshold laser technology, was introduced with the goal of reducing side effects while maintaining the effectiveness of the laser treatments. Several studies focused on Micropulse Diode Laser Trabeculoplasty (MDLT) in open-angle glaucoma, to evaluate its effectiveness and possible side effects. Promising results were reported, but irradiation circumstances have not been standardized yet and its role as a substitute for previous laser techniques has yet to be defined. As a result, the goal of this review was to analyze the physical principles at the basis of MDLT and to frame it in the open-angle glaucoma management setting, highlighting the advantages and shortfalls of this technique.

Comparison of Outcomes for Laser Trabeculoplasty after Kahook Dual Blade Goniotomy Versus in Goniotomy-Naive Eyes

Introduction

This was a comparison of laser trabeculoplasty (LTP) outcomes in eyes with prior Kahook Dual Blade (KDB) goniotomy versus in goniotomy-naive control eyes.

Methods

This was a retrospective matched comparative case series. We identified a cohort of patients undergoing LTP between February 2017 and July 2020 at University of Missouri. Patients were grouped by history of KDB goniotomy versus goniotomy-naivety as a control group. Inclusion criteria included age at least 18 years, minimum of 6 months follow-up after LTP, and minimum period of 6 months between KDB goniotomy and LTP. All KDB procedures were combined with uncomplicated phacoemulsification. Patients who had any additional intraocular pressure (IOP)-lowering procedures between KDB goniotomy and LTP were excluded. Patients in the control group received a single LTP procedure.

Primary outcome consisted of the comparison of LTP success, defined as IOP reduction of at least 20% or reduction of glaucoma medications from pre-LTP baseline. Secondary outcomes included IOP and medication reduction from pre-LTP baseline.

Results

Twenty-one eyes of 19 patients with history of KDB goniotomy and 42 eyes of 36 control patients without previous angle or laser procedures were included. Baseline characteristics including age, gender, ethnicity, type and severity of glaucoma, baseline IOP, and baseline medications were matched between groups. The LTP success rate was higher in the control group, but was not statistically significant (64% vs 57%, p = 0.58). IOP reduction was only significant in the control eyes (2.50 ± 4.0 mmHg, p = 0.01 vs 2.35 ± 4.7 mmHg, p = 0.08). The number of glaucoma medications was not significantly reduced in either group.

Conclusion

LTP may have a limited IOP- and medication-lowering effect in eyes with a history of KDB goniotomy compared to goniotomy-naive eyes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-021-00378-7.

Micropulse laser trabeculoplasty under maximal tolerable glaucoma eyedrops: treatment effectiveness and impact of surgical expertise

AIM

To evaluate the effectiveness of micropulse laser trabeculoplasty (MLT) for eyes with open angle glaucoma (OAG) under maximal tolerable glaucoma eyedrops and to assess the effect of expertise performing MLT on its clinical effectiveness.

METHODS

Medical records of 42 consecutive eyes of 34 patients diagnosed with OAG who underwent MLT were retrospectively reviewed. The effectiveness was determined using the Kaplan-Meier survival analysis. Failure was defined as an intraocular pressure (IOP) reduction of <20% from baseline, an IOP >21 mm Hg during two consecutive follow-up visits, or surgical intervention for OAG. To determine the impact of MLT surgical expertise on clinical effectiveness, the eyes were divided into two groups according to whether the procedure was conducted by an experienced specialist (defined as a glaucoma specialist who had conducted at least ten MLT procedures) or a less experienced glaucoma specialist. The difference in expertise was determined using a log-rank test.

RESULTS

MLT was conducted by three glaucoma specialists. The overall survival rates were 0.76, 0.48, and 0.44 at 1, 3, and 6mo, respectively. The survival rates for MLT performed by a less experienced glaucoma specialist were 0.62, 0.31, and 0.25 (n=21 eyes) at 1, 3, and 6mo, respectively, whereas the survival rates for MLT performed by an experienced glaucoma specialist were 0.90, 0.64, and 0.64 (n=21 eyes) at 1, 3, and 6mo, respectively. The log-rank test showed a significant difference in the survival curves of the two groups (P=0.0061).

CONCLUSION

The 6-month effectiveness of MLT for controlling IOP is relatively limited in eyes with OAG using maximal tolerable glaucoma eyedrops. However, its effectiveness may be improved if performed by a glaucoma specialist with sufficient MLT experience.

Is laser trabeculoplasty the new star in glaucoma treatment?

PURPOSE OF REVIEW

For decades, laser trabeculoplasty has been a well-proven therapeutic option in glaucoma management, and more recently, it has only gained in popularity. One reason for such popularity is that selective laser trabeculoplasty (SLT) is a therapy independent of patient adherence, which is typically low among glaucoma patients. Consequently, the number of studies on SLT has multiplied throughout the past years. This review provides an overview of studies on SLT from the last 12 months.

RECENT FINDINGS

The studies on treatment outcome show a wide range of success rates of SLT reaching between 18 and 88%; however, study designs differ and many studies are not directly comparable. The prospective laser trabeculoplasty for open-angle glaucoma and ocular hypertension (LiGHT) trial has demonstrated good efficacy of SLT - 75% of the eyes achieved their target pressure without drops and 58% after a single SLT.

SUMMARY

SLT has proven to be effective in lowering IOP with satisfactory success rates even after single SLT. SLT is repeatable independent of patient's adherence.

Clinical Outcomes of Micropulse Laser Trabeculoplasty Compared to Selective Laser Trabeculoplasty at One Year in Open-Angle Glaucoma

Background

There is limited long-term data comparing selective laser trabeculoplasty (SLT) to the newer micropulse laser trabeculoplasty (MLT) using a laser emitting at 532 nm. In this study, we determine the effectiveness and safety of MLT compared to SLT.

Design

Retrospective comparative cohort study.

Participants

A total of 85 consecutive eyes received SLT and 43 consecutive eyes received MLT.

Methods

Patients with open-angle glaucoma receiving their first treatment of laser trabeculoplasty were included. Exclusion criteria are prior laser trabeculoplasty, laser cyclophotocoagulation or glaucoma surgery, and follow-up of less than 1 year.

Main Outcome Measures

The primary outcome was success at 1 year, defined as a reduction in intraocular eye pressure (IOP) by ≥20% from baseline or met prespecified target IOP with no additional glaucoma medication or subsequent glaucoma intervention.

Results

Baseline IOP was 18.0 mmHg (95% CI=16.4–19.5) in the MLT group on an average of 1.8 (95% CI=1.4–2.2) glaucoma medications compared to 18.2 mmHg (95% CI=17.2–19.3) for the SLT group on an average of 2.0 (95% CI=1.6–2.3) medications. At 1-hour post-laser, the SLT group had more transient IOP spikes (MLT 5% vs SLT 16%, P=0.10). There was a trend toward increased success in the SLT group compared to MLT at 1 year (relative risk=1.4, 95% CI=0.8–2.5, P=0.30).

Conclusion and Relevance

Eyes had similar success after MLT compared to SLT at 1 year. Laser trabeculoplasty with either method could be offered as treatment with consideration of MLT in those eyes where IOP spikes should be avoided.

Lasers in Glaucoma: an Overview

Lasers have been in use as a treatment modality of glaucoma for more than last four decades. Each passing year has added newer dimensions to the existing laser technologies enhancing their safety and efficacy profile. This has become possible due to continuous research and innovations with proper understanding of the mechanism of action of different variety of lasers as treatment options. Each category of glaucoma has different underlying pathologies. Adequate knowledge and understanding of indications, limitations and hazards of these laser procedures are must before their application for improvising outcome. Recent years have witnessed a revolution this field. A thorough literature search was conducted in PubMed, Medline, the Cochrane Library Database, EMBASE, and Scopus and Google Scholar until May 2020 using the keywords, and all the articles pertaining to the relevant topics were included in this review. Purpose of this review is to summarize the important laser procedures currently in use for managing glaucoma along with updating the readers with recent advances in laser technologies, their extended applications and also analyzing possible future implications.

Predictive Factors for Outcomes of Selective Laser Trabeculoplasty

We sought to  determine predictive factors for selective laser trabeculoplasty (SLT) outcome. 252 eyes from 198 adult patients with open-angle glaucoma who underwent SLT between July 2016 and February 2018 with a minimum 6 month follow up were reviewed. We defined success as ≥20% IOP reduction or ≥1 medication reduction without an IOP lowering procedure. We also evaluated the relationship of these factors to postoperative IOP elevation >5 mmHg (IOP spikes). Our primary outcome measure was association between age, type and severity of glaucoma, pigmentation of the trabecular meshwork (PTM), total energy delivered, and baseline intraocular pressure (IOP) with success. At 2 and 6 months, 33.6% (76/226) and 38.5% (97/252) of eyes met success criteria respectively. Baseline IOP > 18 mmHg was significantly associated with success both at 2 and 6 months, reducing IOP by 5.4 ± 5.3 mmHg (23.7% reduction), whereas those with lower baseline remained at −0.7 ± 4.6 mmHg (4.9% increase) at 6 months (P < 0.001). No other baseline characteristics significantly predicted success or IOP spikes. Patients with higher baseline IOPs had greater success rates and mean IOP reduction at both 2 and 6 months following SLT. Age, type and severity of glaucoma, PTM, or total energy delivery had no association with procedural success or IOP spikes. Patients with higher baseline IOP may experience greater lowering of IOP after SLT. However, SLT may be equally successful for patients with a variety of other characteristics.