[Selective laser trabeculoplasty: results after a first and a second session, overall comparison and results for three indications]

Efficacy of Selective Laser Trabeculoplasty in Primary Angle-closure Glaucoma after Peripheral Iridotomy

Aim

To evaluate the efficacy of selective laser trabeculoplasty (SLT) in Southeast Asian eyes with primary open-angle glaucoma (POAG) vs primary angle-closure glaucoma after peripheral iridotomy (PACG-PI).

Materials and methods

Records of glaucoma patients who underwent SLT and had a 24-month follow-up were reviewed. Pre- and post-treatment intraocular pressure (IOP), percentage of IOP reduction in POAG, and PACG-PI groups, and probability of failure were analyzed. SLT failure was defined as any eye that did not have IOP lower than 20% compared to the baseline or had an IOP higher than the baseline on two consecutive visits. Adding medication, repeating SLT, or surgical intervention to control IOP was also considered a failure.

Results

Sixty-three POAG and 12 PACG-PI eyes were eligible. The mean (standard deviation [SD]) age was 62.9 (10.2) years in POAG and 60.3 (6.2) years in PACG-PI. Mean (SD) prelaser IOP in POAG was 19.0 (4.4) mm Hg and 20.7 (4.7) mm Hg in PACG-PI. At 24 months post-SLT, mean (SD) IOP was 14.1 (4.7) mm Hg and 13.6 (2.0) mm Hg in POAG and PACG-PI, respectively. There was no significant difference in percentage of IOP reduction (22.8 ± 23.0% for POAG and 30.7 ± 19.5% for PACG-PI, p = 0.96), or failure probability (p = 0.10) between both groups.

Conclusion

The efficacy of SLT at 24 months was comparable between POAG and PACG-PI.

Clinical significance

Selective laser trabeculoplasty may be an option to further lower IOP in eyes with angle closure with visible trabecular meshwork (TM) after iridotomy, especially in highly pigmented eyes of Southeast Asians.

How to cite this article

Wongwuticomjon T, Chansangpetch S, Inobhas A, et al. Efficacy of Selective Laser Trabeculoplasty in Primary Angle-closure Glaucoma after Peripheral Iridotomy. J Curr Glaucoma Pract 2022;16(2):124-127.

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.

The effect of repeat 360-degree selective laser trabeculoplasty on intraocular pressure control in open-angle glaucoma

OBJECTIVE

To evaluate the effect of repeat 360-degree selective laser trabeculoplasty (SLT) on intraocular pressure (IOP) with short-term follow-up.

METHODS

This study was based on clinical practice (25 females and 13 males) with a history of primary open-angle glaucoma (27), normotensive glaucoma (6) or pseudoexfoliative glaucoma (5). We measured the IOP at baseline before the first and second 360-degree SLT at 1 month, 6 months and 15 months. Follow-up was concluded earlier if the SLT failed (an increase in IOP over the baseline value), if a new medication was introduced or if an IOP lowering surgery was performed.

RESULTS

Baseline IOP prior to SLT1 was 19.0 ± 3.7 mmHg, which dropped to 16.0 ± 3.7 mmHg (17.0% reduction), 16.9 ± 3.8 mmHg (12.5% reduction) and 17.2 ± 3.3 mmHg (8.7% reduction) at 1, 6 and 15 months respectively (P<0.01). For SLT2, baseline IOP was 18.0 ± 4.5 mmHg, which dropped to 15.1 ± 3.8 mmHg (15.1% reduction), 15.1 ± 4.3 mmHg (15.6% reduction) and 16.0 ± 3.6 mmHg (10.3% reduction) at 1, 6 and 15 months respectively (P<0.01).

CONCLUSION

In a cohort of patients who underwent 360-degree SLT 4 years previously, a second SLT resulted in IOP lowering similar to the first treatment with a possibly more sustained response.