Energy Dose-Response in Selective Laser Trabeculoplasty: A Review

Mechanism of selective laser trabeculoplasty: a systemic review

Although selective laser trabeculoplasty (SLT) is a recognized method for the treatment of glaucoma, the exact changes in the target tissue and mechanism for its intraocular pressure lowing effect are still unclear. The purpose of this review is to summarize the potential mechanisms of SLT on trabecular meshwork both in vivo and in vitro, so as to reveal the potential mechanism of SLT. SLT may induce immune or inflammatory response in trabecular meshwork (TM) induced by possible oxidative damage etc, and remodel extracellular matrix. It may also induce monocytes to aggregate in TM tissue, increase Schlemm's canal (SC) cell conductivity, disintegrate cell junction and promote permeability through autocrine and paracrine forms. This provides a theoretical basis for SLT treatment in glaucoma.

Optimal Performance of Selective Laser Trabeculoplasty: Results from the Swedish Optimal SLT Multicenter Randomized Controlled Trial

PURPOSE

Selective laser trabeculoplasty (SLT) is a first-line treatment for glaucoma and ocular hypertension. However, due to insufficient comparative evidence in efficacy and safety, several SLT treatment protocols are currently used in practice. The objective of this trial was to compare the clinical outcomes of the 4 most significant SLT variants.

DESIGN

Prospective, multicenter, masked, randomized controlled trial (RCT).

PARTICIPANTS

Four hundred patients with glaucoma or ocular hypertension. The cohort consisted of both treatment-naive patients and patients undergoing glaucoma treatment, at different stages of disease.

METHODS

Selective laser trabeculoplasty was performed with 50 ± 5 laser spots in 180 degrees or with 100 ± 10 spots in 360 degrees. The laser power was titrated to either just below the cavitation bubble level ("standard energy") or to a level producing cavitation bubbles at 50% to 75% of laser applications ("high energy"). Thus, 4 different treatment protocols were included - 180/standard, 180/high, 360/standard, and 360/high. The study adhered as close as possible to regular clinical management, but within a scientific framework.

MAIN OUTCOME MEASURES

Reduction of intraocular pressure (IOP) 1 to 6 months after SLT. The proportion of patients achieving a 20% IOP reduction without any further intervention. Time to glaucoma treatment escalation in a Kaplan-Meier survival analysis.

RESULTS

SLT performed with the 360/high protocol was shown to be superior regarding all primary endpoints. The IOP reduction 1 to 6 months after SLT was 5.4 mmHg in the 360/high group, compared to 3.4, 3.2, and 4.2 mmHg with the 180/standard, 180/high, and 360/standard protocols, respectively (P < 0.001). Furthermore, the success rate after 6 months was significantly higher -58.3%, compared with 30.2%, 29.3%, and 41.7% (P < 0.001). The median time to glaucoma treatment escalation was more than twice as long with 360/high SLT -1323 days, compared to 437 days, 549 days, and 620 days (P < 0.001). Although postoperative discomfort was more frequent with the 360/high protocol, symptoms were generally mild and transient. Adverse events were rare in all groups.

CONCLUSIONS

The magnitude and longevity of SLT results increases substantially if SLT is performed according to the 360/high protocol, without compromising safety. Therefore, we recommend that 360/high SLT be considered as standard treatment.

FINANCIAL DISCLOSURES

The authors have no proprietary or commercial interest in any materials discussed in this article.

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.

A Proposal for the Use of a Fixed Low-Energy Selective Laser Trabeculoplasty for Open Angle Glaucoma

Selective laser trabeculoplasty (SLT) has been in routine clinical use for over 20 years with millions of patients successfully treated and a low rate of clinically significant complications. The procedure requires the clinician to manually position the laser beam on the trabecular meshwork using a gonioscopy lens and to titrate the SLT laser energy based on the amount of pigmentation in the angle, as well as the observation of small bubbles produced by the laser effect. We propose that SLT energy titration is unnecessary either to achieve intraocular pressure (IOP) reduction or to minimize potential side effects. Ample evidence to support our proposal includes multiple clinical reports demonstrating comparable levels of IOP reduction resulting from different laser energies, a large variety of energy and other laser parameters used in commercially available SLT lasers, and the nature of the laser-induced changes in the trabecular meshwork tissue with respect to energy. Despite these variations in laser parameters, SLT consistently reduces IOP with a low complication rate. We propose that using low fixed energy for all patients will effectively and safely lower patients' IOP while reducing the complexity of the SLT procedure, potentially making SLT accessible to more patients.