How safe is diode laser peripheral iridoplasty for the corneal endothelium?

Efficacy and safety of laser peripheral iridoplasty with different energy levels and locations in the treatment of primary angle closure disease assessed by swept-source anterior segment optical coherence tomography

BACKGROUND

To explore the efficacy and safety of laser peripheral iridoplasty (LPIp) with different energy levels and locations in the treatment of primary angle closure disease (PACD) assessed by swept-source anterior segment optical coherence tomography (AS-OCT).

METHODS

We enrolled patients with PACD following best-corrected visual acuity (BCVA), intraocular pressure (IOP), anterior chamber gonioscopy, ultrasound biomicroscopy(UBM), optic disc OCT, and visual field examinations. After Pentacam and AS-OCT measurements, the patients were randomly divided into four treatment groups for LPIp with two different energy levels (high vs. low energy) and two locations (far from the periphery vs. near the periphery) and combined with laser peripheral iridotomy. BCVA, IOP, pupil diameter, central anterior chamber depth, anterior chamber volume, anterior opening distance (AOD)500, AOD750, trabecular iris angle (TIA)500, and TIA750 in four quadrants before and after laser treatment were compared.

RESULTS

We followed up 32 patients (64 eyes; average age, 61.80 ± 9.79 years; 8 patients/16 eyes per group) for up to 2 years. The IOP of all enrolled patients was decreased after surgery compared to that before (t = 3.297, P = 0.002), the volume of the anterior chamber was increased (t=-2.047, P = 0.047), and AOD500, AOD750, TIA500, and TIA750 were increased (all P < 0.05). Within-group comparisons showed that BCVA in the low-energy/far-periphery group was improved after surgery (P < 0.05). After surgery, the IOP was decreased in the two high-energy groups, whereas the volume of the anterior chamber, AOD500, AOD750, TIA500, and TIA750 were increased in all groups (all P < 0.05). However, when comparing every two groups, the high-energy/far-periphery group showed a stronger effect on pupil dilation than the low-energy/near-periphery group (P = 0.045). The anterior chamber volume in the high-energy/near-periphery group was larger than that in the high-energy/far-periphery group (P = 0.038). The change in TIA500 was for 6 points smaller in the low-energy/near-periphery group than in the low-energy/far-periphery group (P = 0.038). Other parameters showed no significant group differences.

CONCLUSION

LPIp combined with iridotomy can effectively reduce IOP, increase anterior chamber volume, increase chamber angle opening distance, and widen the trabecular iris angle. Intraoperatively, high-energy laser spots positioned one spot diameter from the scleral spur can obtain the best effect and safety. Swept-source AS-OCT can safely and effectively quantify the anterior chamber angle.

Long-Term Outcome of Corneal and Anterior Chamber Angle Parameters after Combined Laser Iridotomy and Iridoplasty Using Dual Scheimpflug Analyzer: 1 Year Results

Background: To investigate the outcomes of corneal and anterior chamber angle (ACA) parameters after laser iridotomy (LI) combined with peripheral iridoplasty (PI) using dual Scheimpflug analyzer in the long term. Methods: Fifty-eight eyes (58 subjects) with shallow AC were included in this prospective cohort study. Images of the Dual Scheimpflug analyzer were obtained before, 1 week, and 1 year after LI and PI. Pachymetry from three zones (central, middle, and peripheral), corneal aberration, and spherical equivalent (SE) were acquired. AC depth (ACD), AC volume (ACV), ACA from four quadrants, and intraocular pressure (IOP) were also obtained. For comparison of the results, the linear mixed-effects model was employed. Results: ACD significantly increased from 2.09 ± 0.25 mm to 2.10 ± 0.23 mm at 1 year after laser (all p < 0.05). ACV and ACA increased significantly after laser at 1 year (all p < 0.05). IOP significantly decreased from 15.97 ± 4.20 mmHg to 13.73 ± 2.63 mmHg at 1 year (all p < 0.0001). No significant changes were found in the coma, trefoil, total corneal aberration, pachymetry from three zones, corneal volume, central corneal thickness, and SE after LI and PI until 1 year (all p > 0.05). Conclusions: LI plus PI ameliorated parameters of ACA efficiently and significantly reduced IOP in eyes with shallow AC until 1 year of long-term follow-up. However, parameters of the cornea and SE were not influenced by LI with PI until after 1 year.

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.

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.

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.