Repeat selective laser trabeculoplasty for glaucoma patients: A systematic review and meta-analysis

Author: Jang HJ, Yu B, Hodge W, Malvankar-Mehta MS.

Geographical coverage: United States, Canada, the United Kingdom, Saint Lucia, and other Afro-Caribbean countries

Sector: Treatment of glaucoma

Sub-sector: Selective laser trabeculoplasty

Equity focus: Not reported

Study population: Patients with glaucoma

Review type: Effectiveness review

Quantitative synthesis method: Narrative synthesis and meta-analysis

Qualitative synthesis method: Not applicable

Background:

Selective laser trabeculoplasty (SLT) has gained attention as a first-line treatment for open-angle glaucoma (OAG), supported by the LiGHT trial. SLT selectively targets pigmented trabecular meshwork cells to improve aqueous outflow and reduce intraocular pressure (IOP) by 20–30% with minimal tissue damage. It boasts an initial success rate of 80% and circumvents issues such as poor medication compliance and toxicity. However, despite its effectiveness, the long-term IOP-lowering effects of SLT may diminish, necessitating repeat treatments.

Objectives

To synthesise the current literature and evaluate repeat SLT for treating primary open-angle glaucoma (POAG).

Main findings

Overall, repeat SLT appears to be an effective and safe procedure for reducing IOP in glaucoma patients for up to 24 months.

The search identified 206 articles, of which 14 studies were included in the qualitative synthesis and 9 in the meta-analysis. Ten of the 14 included studies were retrospective chart reviews, three were prospective observational studies, and one was a post hoc analysis of a randomised controlled trial (RCT). The included studies were conducted in the United States, Canada, the United Kingdom, Saint Lucia, and other Afro-Caribbean countries. Eight of the 14 studies were rated as fair quality, while the remaining six were of poor quality.

Meta-analysis revealed a significant reduction in IOP at the 1-month follow-up (standardised mean difference [SMD] = −0.96, 95% confidence interval [CI]: −1.35 to −0.57) and at the 19–24-month follow-up (SMD = −0.86, 95% CI: −1.26 to −0.47). Studies evaluating the efficacy of a third SLT treatment reported mixed results: some indicated effectiveness for up to 18–24 months with success rates comparable to earlier SLTs, while others found limited or no significant IOP reduction. Few side effects were reported following either initial or repeat SLT procedures. These included mild discomfort, headache, photophobia, transient IOP spikes, and mild anterior uveitis, all of which resolved quickly.

Methodology

Searches were conducted in PubMed, Embase, CINAHL, grey literature sources, and ARVO/AAO conference abstracts, from inception to May 2020, to identify English-language studies on SLT in adults with POAG.

Two reviewers independently assessed articles for eligibility and resolved discrepancies through discussion. One reviewer evaluated methodological quality using the modified Downs and Black checklist and performed data extraction.

Findings were synthesised using a random-effects model meta-analysis. Effect sizes were reported as standardised mean differences (SMDs) with 95% confidence intervals. Heterogeneity was assessed using I² statistics, Z-values, and χ² statistics. Publication bias was evaluated using a funnel plot.

Applicability / External validity

The review noted that most studies were retrospective and lacked randomisation or control groups. Patient demographics, treatment settings, and follow-up durations varied across studies. High-quality, long-term RCTs are needed to strengthen the external validity of these findings.

Geographic focus

The included studies were conducted in the United States, Canada, the United Kingdom, Saint Lucia, and other Afro-Caribbean countries.

Summary of quality assessment

Overall, confidence in the study’s conclusions is low. Although the authors conducted a thorough database search, they did not examine reference lists of included studies or include non-English-language studies. In addition, data analysis did not account for bias risk, and only one reviewer conducted data extraction.