Argon Laser Peripheral Iridoplasty for Primary Angle-Closure Glaucoma: A Randomized Controlled Trial

Clinical implication of recent randomized control trial in primary angle-closure disease management

Blindness due to primary angle-closure glaucoma (PACG) can be reduced significantly if the ongoing angle-closure process is arrested at an early stage. Various treatments such as laser peripheral iridotomy (LPI), iridoplasty, and clear lens extraction (CLE) have been advocated as first-line therapy for primary angle-closure (PAC), PACG, and high-risk cases of primary angle-closure suspect (PACS). EAGLE study, propagated the effectiveness of CLE over LPI for the management of primary angle closure and have sparked controversy regarding the role of LPI as a first line procedure. Randomized controlled trials (RCT), systematic reviews, and meta-analyses of RCTs done on the same question provide us with a solid base for creating guidelines/modules for our day-to-day clinical practice. A systematic review was conducted, searching several databases, including PubMed, Cochrane Library, EMBASE, and ClinicalTrials.gov, for the last 16 years (January 2005–December 2021) for RCTs with data published related to primary angle-closure disease (PACD). The search strategy included the following terms: “Primary Angle Closure disease,” “Primary Angle Closure Glaucoma,” “Primary Angle Closure,” “Primary Angle Closure Suspect,” “clear lens extraction,” “laser iridotomy,” “laser peripheral iridotomy,” “argon laser peripheral iridoplasty,” “selective laser trabeculoplasty,” “trabeculectomy,” “randomized control trial,” and “meta-analysis of randomized control trial.” In this review, we will discuss recently published RCTs (within the last 16 years) for the management of PACD and their clinical implications in day-to-day practice.

Laser peripheral iridoplasty for chronic angle closure

BACKGROUND

In at least a third of primary angle closure cases, appositional angle closure persists after laser peripheral iridotomy, and further intervention may be considered. Laser peripheral iridoplasty (LPIp) can be used in treating chronic angle closure when angle closure persists after laser peripheral iridotomy. Previous reviews have found insufficient data to determine its clinical effectiveness, compared to other interventions. This is an update of a Cochrane Review first published in 2008 and updated in 2012. It examines all studies to date to establish whether LPIp shows any effectiveness over other available treatment options.

OBJECTIVES

To assess the effectiveness of laser peripheral iridoplasty in the treatment of people with chronic angle closure, when compared to laser peripheral iridotomy, medical therapy or no further treatment.

SEARCH METHODS

We searched various electronic databases. The date of the search was 20 December 2020.

SELECTION CRITERIA

We included only randomised controlled trials (RCTs) assessing the use of LPIp in cases of suspected primary angle closure (PACS), confirmed primary angle closure (PAC), or primary chronic angle-closure glaucoma (PACG). We applied no restrictions with respect to gender, age or ethnicity of participants. Trials evaluating LPIp for acute attacks of angle closure were not eligible.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two authors independently assessed studies for risk of bias using Cochrane's 'risk of bias' tool. We collected adverse effects information from the trials.

MAIN RESULTS

We included four RCTs involving 252 participants (276 eyes). In total, three different methods of intervention were used and 15 outcomes reported, with different time points. We used narrative synthesis to describe the majority of the findings, as meta-analysis was only possible for a limited number of outcomes due to the variation in study design and outcomes assessed. Study Characteristics Participants were adults recruited from outpatient settings in the UK, Singapore, China and Korea with either PACS, PAC or PACG. All studies compared argon LPIp (as either a primary or secondary procedure) to an alternative intervention or no further treatment. Three studies were of parallel group design, and one within-person, randomised by eye. All studies showed elements of high risk of bias. Due to the nature of the intervention assessed, a lack of masking of both participants and assessors was noted in all trials. Findings Laser peripheral iridoplasty with iridotomy versus iridotomy alone as a primary procedure Two RCTs assessed the use of argon LPIp as a primary procedure with peripheral iridotomy, compared with peripheral iridotomy alone. However, neither study reported data for the primary outcome, disease progression. Argon LPIp showed no evidence of effect on: final mean intraocular pressure (IOP) at 3 months and 12 months (mean difference (MD) 0.39 mmHg, 95% confidence interval (CI) -1.07 to 1.85; I² = 38%; 2 studies, 174 participants; low-certainty evidence); further surgical or laser intervention at 12 months (risk ratio (RR) 1.21, 95% CI 0.66 to 2.21; 1 study, 126 participants; low-certainty evidence); or mean number of additional medications required at 12 months (MD 0.10, 95% CI -0.34 to 0.54; 1 study, 126 participants; low-certainty evidence). Complications were assessed at 3 to 12 months (2 studies, 206 participants; low-certainty evidence) and found to be mild and uncommon, with comparable levels between groups. The only severe complication encountered was one case of malignant glaucoma in one study's argon LPIp group. Quality of life measures were not assessed. In the other study, investigators found that argon LPIp showed no evidence of effect on final mean anterior segment optical coherence tomography (AS-OCT) measurements, including anterior chamber depth (MD 0.00 mm, 95% CI -0.10 to 0.10; 24 participants, 48 eyes; very low-certainty evidence). Laser peripheral iridoplasty as a secondary procedure versus no treatment One RCT assessed the use of argon LPIp as a secondary procedure compared with no further treatment in 22 participants over three months. Disease progression, additional medications required, complications, further surgical or laser intervention, and quality of life outcomes were not assessed. There was only very low-certainty evidence regarding final maximum IOP value (MD -1.81 mmHg, 95% CI -3.11 to -0.51; very low-certainty evidence), with no evidence of effect on final minimum IOP values (MD -0.31 mmHg, 95% CI -1.93 to 1.31; very low-certainty evidence). The evidence is very uncertain about the effect of argon LPIp on AS-OCT parameters. The trial did not report AS-OCT measurements for the control group. Laser peripheral iridoplasty as a secondary procedure versus medication One RCT assessed the use of argon LPIp as a secondary procedure compared with travoprost 0.004% in 80 participants over 12 months. The primary outcome of disease progression was reported for this method: argon LPIp showed no evidence of effect on mean final cup/disk ratio (MD -0.03, 95% CI -0.11 to 0.05; low-certainty evidence). Argon LPIp showed no evidence of effect for: mean change in IOP (MD -1.20 mmHg, 95% CI -2.87 to 0.47; low-certainty evidence) or mean number of additional medications (MD 0.42, 95% CI 0.23 to 0.61; low-certainty evidence). Further surgical intervention was required by one participant in the intervention group alone, with none in the control group  (low-certainty evidence). No serious adverse events were reported, with mild complications consisting of two cases of 'post-laser IOP spike' in the argon LPIp group. Quality of life measures were not assessed. The evidence is very uncertain about the effect of argon LPIp on AS-OCT parameters. The trial did not report AS-OCT measurements for the control group. Adverse events Availability of data were limited for adverse effects. Similar rates were observed in control and intervention groups, where reported. Serious adverse events were rare.

AUTHORS' CONCLUSIONS

After reviewing the outcomes of four RCTs, argon LPIp as an intervention may be no more clinically effective than comparators in the management of people with chronic angle closure. Despite a potential positive impact on anterior chamber morphology, its use in clinical practice in treating people with chronic angle closure is not supported by the results of trials published to date. Given these results, further research into LPIp is unlikely to be worthwhile.

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.

Corneal topography and angle parameters after laser iridotomy combined with iridoplasty assessed by dual Scheimpflug analyzer

PURPOSE

To investigate the changes in corneal topography including parameters such as corneal curvature and corneal aberrations, along with anterior chamber angle (ACA) after laser iridotomy (LI) combined with peripheral iridoplasty (PI) using dual Scheimpflug analyzer.

METHODS

In this prospective observational study, dual Scheimpflug analyzer images were acquired before and 1 week after LI plus PI. Corneal curvature of both axial and instantaneous maps from anterior and posterior surface, respectively, and total corneal power (TCP) were acquired. These corneal parameters from three zones (central, middle, and peripheral) and total corneal wavefront aberration, trefoil, and coma were obtained. The ACA from four quadrants, anterior chamber depth (ACD), anterior chamber volume (ACV), and intraocular pressure (IOP) were also inspected.

RESULTS

ACD increased significantly from 2.15 ± 0.25 to 2.18 ± 0.24 mm (P = 0.002). ACV and ACA from all four quadrants increased significantly after the laser treatment (all P < 0.05). IOP decreased significantly from 16.9 ± 3.1 to 14.7 ± 2.9 mmHg following LI plus PI (P = 0.000). No significant changes were detected in corneal axial and instantaneous curvature from three zones on the anterior and posterior corneal surface after LI plus PI (all P > 0.05). The TCP, total corneal wavefront aberration, trefoil, and coma also revealed no significant changes after the laser procedure (all P > 0.05).

CONCLUSIONS

Treatment with LI combined with PI did not affect the corneal topographic parameters from both anterior and posterior surfaces. However, LI plus PI improved ACA parameters significantly and effectively.

Pattern Scanning Laser (PASCAL) for Peripheral Iridoplasty in Eyes With Plateau Iris Syndrome: A Novel Application

PURPOSE

The purpose of this study was to evaluate safety and efficacy of pattern scanning laser (PASCAL) for peripheral iridoplasty in eyes with plateau iris syndrome.

MATERIALS AND METHODS

This study was a retrospective review of cases that underwent PASCAL laser peripheral iridoplasty. Eyes with plateau iris syndrome confirmed on gonioscopy and ultrasound biomicroscopy were included in the study. Primary and secondary outcome measures were angle widening on gonioscopy and magnitude of intraocular pressure (IOP) reduction, respectively.

RESULTS

Twelve eyes of 8 patients that completed 1-year follow-up were analyzed. Angle widening was noted in 46% of treated quadrants by at least 1 grade (Shaffer classification) at 1-month follow-up. A statistically significant IOP reduction was noted at 1 year from 20.6±4.8 to 17.8±3.8 mm Hg (P=0.01). At 1 month, 8 of 12 eyes (66.6%) achieved gonioscopic success (widening of the angle by at least 1 grade in 2 of 4 quadrants). At 1 year, 6 of 12 eyes (50%) achieved tonometric success (20% reduction or 3 mm Hg IOP reduction from the baseline without addition of new antiglaucoma medications). No adverse effects associated with PASCAL laser peripheral iridoplasty were observed.

CONCLUSIONS

PASCAL laser iridoplasty can be a safe and effective alternative to argon laser peripheral iridoplasty in the management of eyes with plateau iris syndrome. Our findings need to be further validated on larger sample size and in different ethnicities.

Combined treatment of phacoemulsification and single-port limited pars plana vitrectomy in acute angle-closure glaucoma

AIM

To evaluate the efficacy of combined treatment of phacoemulsification (PE) and micro-incisional single-port transconjunctival limited pars plana vitrectomy (PPV) in acute angle-closure glaucoma (AACG).

METHODS

A retrospective study included 26 patients who underwent PE diagnosed with AACG. Among them, 16 patients (16 eyes) underwent PE alone, 10 patients (10 eyes) underwent combined limited vitrectomy and PE. Then we compared intraocular pressure (IOP), anterior chamber angle, anterior chamber depth, central corneal thickness and corneal endothelial cell count before and after surgery, and effective PE time during cataract surgery.

RESULTS

Effective PE time was shorter in the combined surgery group than in the single surgery group (P=0.040). There was no statistically significant difference in IOP and best-corrected visual acuity between the two groups postoperatively. At 6mo postoperatively, there was no difference in the anterior chamber angle, anterior chamber depth, and central corneal thickness between two groups, but corneal endothelial cell count was higher in the combined surgery group than in the single surgery group (P=0.046). No complication such as vitreoretinal disease, endophthalmitis, bullous keratopathy was noted.

CONCLUSION

Combined micro-incisional single-port transconjunctival limited PPV and PE are more effective and safer than PE alone because of less operation time and fewer complications for management of AACG.

Argon laser peripheral iridoplasty for chronic primary angle-closure and angle-closure glaucoma in caucasians

PURPOSE

To investigate whether the peripheral thinning and shrinking of the iris as induced with Argon laser peripheral iridoplasty (ALPI) has an effect on intraocular pressure (IOP), angle structure and 3-D anterior segment (AS) morphology in Caucasians with chronic primary angle-closure (PAC) and primary angle-closure glaucoma (PACG).

METHODS

Twenty-four eyes of 24 patients (age 67.7 ± 8.9 years; seven males; 17 females) diagnosed with PAC (n = 10) or PACG (n = 14) were assigned for ALPI prior to laser peripheral iridotomy (LPI) and consecutively enrolled in this prospective interventional study. Intraocular pressure (IOP) was measured with Goldmann applanation tonometry, angle structure with gonioscopy using the Shaffer grading system and AS morphology with the Pentacam rotating Scheimpflug camera prior to and 3 months after ALPI. Intraocular pressure (IOP)-lowering medication was not changed during follow-up.

RESULTS

Intraocular pressure (IOP) changed statistically significantly from 18.8 ± 3.6 to 14.7 ± 3.1 mmHg (p < 0.001). Gonioscopy showed a statistically significant angle widening in all four quadrants: nasally from Shaffer 1.04 ± 0.98 to 2.54 ± 1.1 (p < 0.001), superiorly from 0.39 ± 0.66 to 1.58 ± 1.21 (p < 0.001), temporally from 0.87 ± 1.01 to 2.17 ± 1.24 (p = 0.001) and inferiorly from 1.22 ± 0.74 to 2.75 ± 0.9 (p < 0.001). Pentacam parameters like anterior chamber depth, volume and angle did not increase statistically significantly.

CONCLUSION

Argon laser peripheral iridoplasty (ALPI) is a safe and effective procedure for reducing appositional angle-closure and thus IOP in nonacute PAC and PACG patients.

Lasers in glaucoma

While lasers have been used for many years for the treatment of glaucoma, proper indications and use of the procedures need to be considered before their application. This review summarizes the important laser procedures in Glaucoma.

Quantitative assessment of changes in anterior segment morphology after argon laser peripheral iridoplasty: findings from the EARL study group

IMPORTANCE

Argon laser peripheral iridoplasty (ALPI) could be effective in widening residual angle closure following laser peripheral iridotomy (LPI).

BACKGROUND

We investigated changes in angle parameters following ALPI and its safety profile in this study.

DESIGN

Retrospective, observational case series.

PARTICIPANTS

The records from a single centre, of 36 patients (60 eyes) who underwent ALPI, for residual angle closure following LPI, were reviewed.

METHODS

We analysed anterior chamber parameters in anterior segment optical coherence tomography (ASOCT) images using customized software pre- and post-ALPI. Paired t-test was used to compare changes.

MAIN OUTCOME MEASURES

ASOCT parameters analysed included angle opening distance (AOD 500 and 750), trabecular iris surface area (TISA 500 and 750), anterior chamber width (ACW), anterior chamber volume (ACV), angle recess area (ARA), anterior chamber area (ACA), anterior chamber depth (ACD) and lens vault (LV).

RESULTS

There was a mean increase in AOD 500 (0.05 vs. 0.16 mm, P < 0.001), AOD 750 (0.15 vs. 0.27 mm, P < 0.001), TISA 500 (0.010 vs. 0.038 mm² , P < 0.001), TISA 750 (0.039 vs. 0.102 mm² , P < 0.001), ACV (89.76 vs. 102.25 mm³ , P = 0.01), ARA 500 (0.015 vs. 0.033 mm² , P < 0.001) and ARA 750 (0.044 vs. 0.088 mm² , P < 0.001). There was no significant change in ACW, ACD, ACA and LV. Mean intraocular pressure (IOP) decreased post-ALPI (17.2 vs. 15.7 mmHg, P = 0.002). The mean follow-up duration was 2.1 years (range 0.5-5 years).

CONCLUSIONS AND RELEVANCE

ALPI results in changes to the angle morphology and lowered IOP in eyes with residual angle closure. Our findings suggest a possible role for ALPI in eyes with residual angle closure following peripheral iridotomy.

Contemporary approach to the diagnosis and management of primary angle-closure disease

The primary angle-closure disease spectrum varies from a narrow angle to advanced glaucoma. A variety of imaging technologies may assist the clinician in determining the pathophysiology and diagnosis of primary angle closure, but gonioscopy remains a mainstay of clinical evaluation. Laser iridotomy effectively eliminates the pupillary block component of angle closure; however, studies show that, in many patients, the iridocorneal angle remains narrow from underlying anatomic issues, and increasing lens size often leads to further narrowing over time. Recent studies have further characterized the role of the lens in angle-closure disease, and cataract or clear lens extraction is increasingly used earlier in its management. As a first surgical step in angle-closure glaucoma, lens extraction alone often effectively controls the pressure with less risk of complications than concurrent or stand-alone glaucoma surgery, but may not be sufficient in more advanced or severe disease. We provide a comprehensive review on the primary angle-closure disease nomenclature, imaging, and current laser and surgical management.

The association between serum uric acid and glaucoma severity in primary angle closure glaucoma: a retrospective case-control study

Uric acid (UA) is a major antioxidant molecule and has been hypothesized to have a protective effect on the central nervous system against oxidative damage. We prospectively investigated the serum concentration of UA in primary angle closure glaucoma (PACG), and explored the association between serum concentration of UA and the severity of PACG. Using a retrospective case-control study design, 886 PACG subjects and 994 control subjects who attended the Eye & ENT Hospital of Fudan University, were eligible for this study. Glaucoma severity was classified as mild (MD ≤ 6.00 dB), moderate (12 dB ≥ MD > 6 dB) and severe (MD > 12 dB) based on the MD (mean deviation). The levels of UA were significantly lower (p = 0.025) in PACG (0.286 ± 0.082 mmol/l) compared with control (0.295 ± 0.085 mmol/l). The mean serum UA levels were lowest in the severe group (0.281 ± 0.074 mmol/l) followed by moderate (0.282 ± 0.080 mmol/l) and mild (0.297 ± 0.090 mmol/l) with significant differences among the three groups (p = 0.032). In multivariate regression analysis, there was a significant negative correlation between UA level and vertical cup-disc ratio (B = −0.165, p = 0.035). Significantly lower serum UA concentration in PACG and its negative association with disease severity presented it as an important candidate in reaction to oxidative stress in glaucoma pathogenesis.

Medium-term Anatomical Results of Laser Peripheral Iridoplasty: An Anterior Segment Optical Coherence Tomography Study

Aim

To evaluate by anterior segment optical coherence tomography (AS-OCT) the medium-term (mean duration 3.2 years) anatomical changes in the anterior chamber angle (ACA) after laser peripheral iridoplasty.

Materials and methods

This is a longitudinal, retrospective case series of 31 eyes of 31 patients with primary angle-closure suspicion, primary angle closure (PAC), or primary angle-closure glaucoma (PACG) who underwent laser peripheral iridoplasty. All patients had persistent iridotrabecular contact (ITC) despite the presence of a patent peripheral iridotomy (PI). An AS-OCT was performed in dark conditions before and after laser iridoplasty. Quadrants of ITC, intraocular pressure (IOP), and the AS-OCT parameters of the temporal and nasal ACAs were measured and analyzed.

Results

Prior to iridoplasty, the average number of quadrants of ITC was 3.3. At the first postiridoplasty visit (mean duration 6.8 weeks), this reduced to 1.7 quadrants but increased to 1.9 by the final follow-up visit (mean duration 3.2 years). Twenty-five patients (80.1%) had less ITC at the first postlaser visit increasing to 27 (87.1%) patients by the final visit. Two (6.5%) required a second iridoplasty, while 3 (9.7%) required cataract surgery. All parameters of angle width showed a statistically significant increase in magnitude. All patients maintained IOP ≥ 21 mm Hg throughout the follow-up period.

Conclusion

Iridoplasty is a useful adjunct in widening the ACA, particularly in those with persistent angle closure after iridotomy but with no cataract. While not successful in all patients, it can act as a temporizing measure to widen the drainage angle until such time that cataract surgery can be performed.

Clinical significance

Laser peripheral iridoplasty can be used as an adjunct in angle-closure glaucoma patients with no cataract.

How to cite this article: Hooshmand J, Leong JCY, O’Connor J, Ang GS, Wells AP. Medium-term Anatomical Results of Laser Peripheral Iridoplasty: An Anterior Segment Optical Coherence Tomography Study. J Curr Glaucoma Pract 2017;11(3):113-119.

Temporal ocular coherence tomography-measured changes in anterior chamber angle and diurnal intraocular pressure after laser iridoplasty: IMPACT study

Aims

To evaluate temporal change in anterior chamber angle anatomy following argon laser peripheral iridoplasty (ALPI) in eyes with occludable angles postlaser peripheral iridotomy (LPI) compared with control eyes. Additionally, the effect on diurnal intraocular pressure (DIOP) fluctuation (maximum-minimum IOP) was investigated.

Methods

Twenty-two patients with bilateral primary angle closure/suspects with gonioscopically occludable anterior chamber angles following LPI were randomised to receive ALPI (n=11) or no further treatment (n=11). Angle opening distance (AOD), trabecular-iris angle, angle recess area and trabecular-iris space area were measured over eight sections with swept-source anterior segment optical coherence tomography and DIOP was measured pre-LPI and repeated at 3 months after ALPI (hourly measures).

Results

All angle parameters increased following ALPI. This change was maintained for 3 months in seven of the eight sections (eg, inferotemporal AOD500 increased by 0.063 mm, p=0.004 at 1 day; 0.051 mm, p=0.029 at 1 week; 0.059 mm, p=0.006 at 6 weeks and 0.056 mm, p=0.011 at 3 months). The only exception was in the inferior sector (eg, AOD500 increased by 0.041 mm, p=0.025 at 1 day and by 0.029 mm, p=0.054 at 3 months). DIOP at 3 months was significantly reduced (5.04 mm Hg; ±1.61 mm Hg) compared with controls (6.61 mm Hg; ±1.63 mm Hg). Maximum IOP was significantly greater in the non-ALPI group (1.87 mm Hg, p=0.026).

Conclusions

ALPI widened all angle sections in eyes that remained occludable post-LPI. Changes were maintained for 3 months. ALPI decreased DIOP fluctuation in the treated eyes by lowering the maximum IOP value.

An Overview of Treatment Methods for Primary Angle Closure

BACKGROUND

Glaucoma is the second leading cause of blindness in the world. Angle closure glaucoma accounts for 25% of all glaucoma, with Asia having the highest rate. Angle closure is an anatomical variation, making the Inuit, Chinese, and other Asians more susceptible. Current treatments include medical, laser, and surgical modalities.

PURPOSE

To identify the current treatment protocols for primary angle closure.

DISCUSSION

The current general protocol to treat angle closure is to lower the intraocular pressure with medications and perform laser iridotomy. However, cataract surgery, laser iridoplasty, goniosynechiolysis, diode cyclophotocoagulation, and filtering surgery are additional treatment modalities used for primary angle closure.

CONCLUSION

Primary angle closure occurs due to various anatomical angle variations. Laser iridotomy is not the sole method of treatment. Specifically, cataract surgery can be particularly effective in the treatment and prevention of angle closure. Recalcitrant cases can be treated with trabeculectomy and shunt implants, although these are not usually first-line treatments.