Comparison between 90-degree and 360-degree selective laser trabeculoplasty (SLT): A 2-year follow-up

Selective laser trabeculoplasty: An updated narrative review

Selective laser trabeculoplasty (SLT) has experienced a resurgence in interest, primarily driven by promising findings from the Laser in Glaucoma and Ocular Hypertension Trial. By offering SLT as an initial drug-free treatment option, we may be able to thwart issues such as adherence and persistence that plague our current medical management protocols. In this comprehensive narrative review, we delve into the current body of literature that explores the utility of SLT across a wide spectrum of scenarios and glaucoma subtypes. We present evidence that provides valuable insight into the efficacy and benefits of SLT, positioning it as a viable option in the management of glaucoma. Careful consideration of the associated risks and challenges is also necessary for successful adoption into clinical practice. Despite the ample evidence supporting SLT's efficacy, some questions remain regarding its long-term effects and the potential need for retreatment. This review aims to shed light on these aspects to guide clinicians in making informed decisions and tailoring treatment plans to individual patient needs. This review also provides the readers with a bird's eye view of the potential impact of SLT and adds clarity to the various therapeutic protocols that one can follow to ensure optimal clinical outcomes for our patients.

Selective Laser Trabeculoplasty for the Treatment of Glaucoma: A Report by the American Academy of Ophthalmology

PURPOSE

To review the current published literature for high-quality studies on the use of selective laser trabeculoplasty (SLT) for the treatment of glaucoma. This is an update of the Ophthalmic Technology Assessment titled, "Laser Trabeculoplasty for Open-Angle Glaucoma," published in November 2011.

METHODS

Literature searches in the PubMed database in March 2020, September 2021, August 2022, and March 2023 yielded 110 articles. The abstracts of these articles were examined to include those written since November 2011 and to exclude reviews and non-English articles. The panel reviewed 47 articles in full text, and 30 were found to fit the inclusion criteria. The panel methodologist assigned a level I rating to 19 studies and a level II rating to 11 studies.

RESULTS

Data in the level I studies support the long-term effectiveness of SLT as primary treatment or as a supplemental therapy to glaucoma medications for patients with open-angle glaucoma. Several level I studies also found that SLT and argon laser trabeculoplasty (ALT) are equivalent in terms of safety and long-term efficacy. Level I evidence indicates that perioperative corticosteroid and nonsteroidal anti-inflammatory drug eye drops do not hinder the intraocular pressure (IOP)-lowering effect of SLT treatment. The impact of these eye drops on lowering IOP differed in various studies. No level I or II studies exist that determine the ideal power settings for SLT.

CONCLUSIONS

Based on level I evidence, SLT is an effective long-term option for the treatment of open-angle glaucoma and is equivalent to ALT. It can be used as either a primary intervention, a replacement for medication, or an additional therapy with glaucoma medications.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Laser trabeculoplasty for open-angle glaucoma and ocular hypertension

BACKGROUND

Open-angle glaucoma (OAG) is an important cause of blindness worldwide. Laser trabeculoplasty, a treatment modality, still does not have a clear position in the treatment sequence.

OBJECTIVES

To assess the effects of laser trabeculoplasty for treating OAG and ocular hypertension (OHT) when compared to medication, glaucoma surgery or no intervention. We also wished to compare the effectiveness of different laser trabeculoplasty technologies for treating OAG and OHT.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2021, Issue 10); Ovid MEDLINE; Ovid Embase; the ISRCTN registry; LILACS, ClinicalTrials.gov and the WHO ICTRP. The date of the search was 28 October 2021. We also contacted researchers in the field.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing laser trabeculoplasty with no intervention, with medical treatment, or with surgery in people with OAG or OHT. We also included trials comparing different types of laser trabeculoplasty technologies.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane. Two authors screened search results and extracted data independently. We considered the following outcomes at 24 months: failure to control intraocular pressure (IOP), failure to stabilise visual field progression, failure to stabilise optic neuropathy progression, adverse effects, quality of life, and costs. We graded the 'certainty' of the evidence using GRADE.

MAIN RESULTS

We included 40 studies (5613 eyes of 4028 people) in this review. The majority of the studies were conducted in Europe and in the USA. Most of the studies were at risk of performance and/or detection bias as they were unmasked. None of the studies were judged as having low risk of bias for all domains. We did not identify any studies of laser trabeculoplasty alone versus no intervention. Laser trabeculoplasty versus medication Fourteen studies compared laser trabeculoplasty with medication in either people with primary OAG (7 studies) or primary or secondary OAG (7 studies); five of the 14 studies also included participants with OHT. Six studies used argon laser trabeculoplasty and eight studies used selective laser trabeculoplasty. There was considerable clinical and methodological diversity in these studies leading to statistical heterogeneity in results for the primary outcome "failure to control IOP" at 24 months.  Risk ratios (RRs) ranged from 0.43 in favour of laser trabeculoplasty to 1.87 in favour of medication (5 studies, I2 = 89%). Studies of argon laser compared with medication were more likely to show a beneficial effect compared with studies of selective laser (test for interaction P = 0.0001) but the argon laser studies were older and the medication comparator group in those studies may have been less effective. We considered this to be low-certainty evidence because the trials were at risk of bias (they were not masked) and there was unexplained heterogeneity. There was evidence from two studies (624 eyes) that argon laser treatment was associated with less failure to stabilise visual field progression compared with medication (7% versus 11%, RR 0.70, 95% CI 0.42 to 1.16) at 24 months and one further large recent study of selective laser also reported a reduced risk of failure at 48 months (17% versus 26%) RR 0.65, 95% CI 0.52 to 0.81, 1178 eyes). We judged this outcome as moderate-certainty evidence, downgrading for risk of bias. There was only very low-certainty evidence on optic neuropathy progression. Adverse effects were more commonly seen in the laser trabeculoplasty group including peripheral anterior synechiae (PAS) associated with argon laser (32% versus 26%, RR 11.74, 95% CI 5.94 to 23.22; 624 eyes; 2 RCTs; low-certainty evidence); 5% of participants treated with laser in three studies of selective laser group had early IOP spikes (moderate-certainty evidence). One UK-based study provided moderate-certainty evidence that laser trabeculoplasty was more cost-effective.  Laser trabeculoplasty versus trabeculectomy Three studies compared laser trabeculoplasty with trabeculectomy. All three studies enrolled participants with OAG (primary or secondary) and used argon laser. People receiving laser trabeculoplasty may have a higher risk of uncontrolled IOP at 24 months compared with people receiving trabeculectomy (16% versus 8%, RR 2.12, 95% CI 1.44 to 3.11; 901 eyes; 2 RCTs). We judged this to be low-certainty evidence because of risk of bias (trials were not masked) and there was inconsistency between the two trials (I2 = 68%). There was limited evidence on visual field progression suggesting a higher risk of failure with laser trabeculoplasty. There was no information on optic neuropathy progression, quality of life or costs. PAS formation and IOP spikes were not reported but in one study trabeculectomy was associated with an increased risk of cataract (RR 1.78, 95% CI 1.46 to 2.16) (very low-certainty evidence).

AUTHORS' CONCLUSIONS

Laser trabeculoplasty may work better than topical medication in slowing down the progression of open-angle glaucoma (rate of visual field loss) and may be similar to modern eye drops in controlling eye pressure at a lower cost. It is not associated with serious unwanted effects, particularly for the newer types of trabeculoplasty, such as selective laser trabeculoplasty.

Laser in Glaucoma and Ocular Hypertension Trial (LIGHT) in China - A Randomized Controlled Trial: Design and Baseline Characteristics

PURPOSE

To describe the baseline characteristics of a trial to evaluate whether selective laser trabeculoplasty (SLT), as a first-line treatment, provides superior economic and health-related quality of life outcomes to medical treatment in China.

DESIGN

The LiGHT China trial is an unmasked, single-center, pragmatic, randomized controlled trial.

METHODS

A total of 771 previously undiagnosed patients with primary open angle glaucoma (POAG, 622 patients) or ocular hypertension (OHT, 149 patients) at Zhongshan Ophthalmic Center were recruited from March 2015 to January 2019. Subjects were randomized to SLT-1st (followed by medication then surgery when required) or Medicine-1st (medication followed by surgery when required). The primary outcome was health-related quality of life (HRQL). The secondary outcomes were clinical outcomes, cost, cost-effectiveness, Glaucoma Utility Index, Glaucoma Symptom Scale, visual function, and safety.

RESULTS

The mean age of POAG patients was 49.8 years and 38.8 years for OHT. The median intraocular pressure was 20 mm Hg for the 1,105 POAG eyes and 24 mm Hg for the 271 OHT eyes. POAG eyes had thinner central cornea thickness (CCT, 536 µm) than OHT eyes (545 µm). Median mean deviation of the visual field in POAG eyes was -4.2 dB. Median refractive error was -1.5 D for OHT eyes and -1.25 D for POAG eyes. There was no difference between POAG and OHT patients on baseline scores of GUI, GSS and VF-14. The difference between OHT and POAG on the EQ-5D-5L was 0.024.

CONCLUSIONS

Compared with participants in the LiGHT UK trial, participants in this trial were younger, more myopic and had more severe visual field defects.

Laser Trabeculoplasty for Open-Angle Glaucoma: A Systematic Review and Network Meta-Analysis

PURPOSE

We sought to comprehensively evaluate the effectiveness of different types of laser trabeculoplasty (LT) in the treatment of open-angle glaucoma.

DESIGN

Systematic review and network meta-analysis.

METHODS

Eligible randomized controlled trials were identified by searching PubMed, EMBASE, Cochrane Library, SCOPUS, China National Knowledge Infrastructure, and the Chinese Biomedical Literature Service System for studies published between January 1, 2000 and April 20, 2020. Eight interventions were evaluated, including argon LT (ALT), medications, 180-degree selective LT (SLT), 270-degree SLT, 360-degree SLT, new LT, transscleral 360-degree SLT with SLT performed without gonioscopy, and low-energy 360-degree SLT. The primary outcome was reduction of medicated and unmedicated intraocular pressure (IOP) at 6 months. Secondary outcomes included reduction of IOP at 12 months, incidences of complications, and change in number of medications. Head-to-head meta-analysis and network meta-analysis were performed using Stata and R software.

RESULTS

In total, 22 studies were included, involving 2859 eyes of 2704 patients. In terms of IOP reduction at 6 and 12 months, there were no statistically significant differences in both medicated and unmedicated IOP between any pairs of interventions considered herein, as determined based on both head-to-head and network meta-analyses (all P > .05). In terms of reduction of medications, the individuals treated with 180-degree SLT required fewer medications than those treated with ALT at 12 months (0.28 [95% confidence interval, 0.06-0.50]; P = .014). No severe adverse outcomes were reported for any of the interventions.

CONCLUSIONS

All the available types of LT are equally effective for decreasing IOP compared with medication-based therapy. The 180-degree SLT was slightly more effective than ALT in terms of reducing the number of medications needed. Additional well-performed randomized controlled trials with larger sample sizes are needed.

Selective Laser Trabeculoplasty in the Treatment of Ocular Hypertension and Open-Angle Glaucoma: Clinical Review

Selective laser trabeculoplasty (SLT) is a glaucoma treatment that reduces intraocular pressure (IOP). Its mechanism is based on the biological effects of the selective application of laser energy to pigmented trabecular meshwork (TM) cells, resulting in increased outflow facility. Herein, we review current publications on SLT and summarize its efficacy and safety for different indications in open-angle glaucoma (OAG) and ocular hypertension (OHT) treatment. SLT effectively reduces IOP when used as a primary treatment. In patients whose IOP is medically controlled, SLT helps to reduce medication use, and when maximally tolerated topical therapy is ineffective, SLT facilitates the realization of the target IOP. SLT is a repeatable procedure for which the vast majority of complications are mild and self-limiting. With effective IOP reduction, low complication rates and the potential to repeat the procedure, SLT offers the possibility of delaying the introduction of medical therapy and other more invasive treatment modalities while simultaneously avoiding the accompanying complications. With this knowledge, we suggest that SLT be considered as an essential primary treatment option in OAG and OHT, switching to other treatment modalities only when laser procedures are insufficient for achieving the required target IOP.

Low-energy Selective Laser Trabeculoplasty Repeated Annually: Rationale for the COAST Trial

The recent Laser in Glaucoma and Ocular Hypertension Trial provided the evidentiary basis for a paradigm shift away from the historical medication-first approach to glaucoma--which has numerous limitations, the most important of which is poor adherence to therapy --and toward a laser-first approach. Now 20 years after its commercialization, selective laser trabeculoplasty (SLT) is routinely performed consistently with its initial description, with energy titrated to the appearance of fine, champagne-like cavitation bubbles. A recent data set suggested that lower energy SLT, applied as primary therapy and repeated annually irrespective of intraocular pressure--rather than pro re nata when its effect wanes and irrespective of intraocular pressure rises --yields longer medication-free survival than standard energy SLT repeated pro re nata. A new study--Clarifying the Optimal Application of SLT Therapy --has been initiated to explore this preliminary finding in a pair of consecutive randomized trials. Herein, we provide an evidence-based rationale for the use of low-energy SLT repeated annually as primary therapy for mild to moderate primary open-angle glaucoma or high-risk ocular hypertension.

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.

[Preliminary selective laser trabeculoplasty (SLT) intraocular pressure results in glaucoma patients in Burkina Faso]

INTRODUCTION

Glaucoma is the leading cause of irreversible blindness in the world. The purpose of our study was to evaluate the tonometric results of SLT treatment in patients with glaucoma.

MATERIALS AND METHODS

This was a prospective study of patients with glaucoma who were seen from October 1, 2017 to July 31, 2018. All patients underwent SLT of the inferior 180°. Intraocular pressure (IOP) was measured before and then at 1, 15, 30, 60, 90 and 120days after treatment.

RESULTS

We studied 35 eyes of 31 patients. The mean age was 59.3 (±8.4years), range 43-77years. The mean IOP prior to SLT was 20.1mmHg (±7mmHg). One day after the laser, this decreased to 17.6mmHg (±8.4), for a percentage of drop of 12.4%. At 30days, it was 15.3mmHg (±5.4mmHg), i.e. a 23.9% decrease. After 60 and 90days, there was a drop of 13.9% and 15.4%, respectively. At 120days, 43.3% of treated eyes had a decrease of at least 20%. The main complication was increased IOP in 14.2% of cases.

CONCLUSION

SLT reduces IOP and the number of glaucoma medications in patients. It appears to be a viable alternative in our countries. These results should be confirmed with a larger cohort and longer follow-up.

Selective Laser Trabeculoplasty Protects Glaucoma Progression in the Initial Primary Open-Angle Glaucoma and Angle-Closure Glaucoma after Laser Peripheral Iridotomy in the Long Term

Purpose

To compare the ability of SLT in preventing glaucoma progression in the initial primary angle-closure glaucoma (PACG) after laser peripheral iridotomy and primary open-angle glaucoma (POAG) in the long term.

Methods

60 patients with the initial stage of PACG after laser peripheral iridotomy and 64 initial POAG patients were recruited in a prospective study. Complete success of selective laser trabeculoplasty (SLT) was defined as a 20% intraocular pressure (IOP) reduction with topical hypotensive medications without any hypotensive intervention. Pre-SLT rate of progression and post-SLT rate of progression (ROP) was detected in the both groups by means of the trend and the event analysis of perimetry, the Guided Progression Analysis, and the optical coherence tomography- (OCT-) based negative trend for either the thickness of the peripapillary retinal nerve fiber layer (RNFL) or ganglion cell complex (GCC).

Results

IOP decreased significantly after SLT in both the groups. 30% in PACG and 19% in POAG had the progression according to perimetry and 49% in PACG and 40% in POAG had the progression, respectively, according to OCT. After SLT, ROP was reduced from -0.14 ± 0.39 dB/year to -0.08 ± 0.48 dB/year, p=0.034, in PACG and from -0.09 ± 0.36 dB/year to -0.04 ± 0.43 dB/year, p=0.021, in POAG. According to RNFL trend analysis, ROP was reduced from -1.86 ± 2.9 μm/year to -1.38 ± 2.2 μm/year, p=0.039, and from -1.24 ± 2.23 μm/year to -0.76 ± 1.73 μm/year, p=0.037, in PACG and POAG, and according to GCC, ROP was reduced from -1.88 ± 2.9 μm/year to -1.34 ± 2.0 μm/year, p=0.040, and from -1.35 ± 2.16 μm/year to -0.91 ± 1.86 μm/year, p=0.040, in PACG and POAG, respectively. ROP was significantly faster in PACD than in POAG between 2 and 6 years after SLT: -0.15 ± 0.46 dB/year and 0.02 ± 0.38 dB/year (p=0.042). However, it did not differ significantly according to OCT.

Conclusion

SLT is an effective treatment for initial PACG after LPI and POAG that can prevent functional and structural deterioration in the long term.