Fixed High Energy Versus Standard Titrated Energy Settings for Selective Laser Trabeculoplasty
Authors: Danielson David T. , Purt Boonkit , Jin Sean J. , Cox Anthony R. , Hess Ruston L. , Kim Won I. 
Published: June 2023

Précis:
Fixed high-energy selective laser trabeculoplasty (SLT) is associated with a greater reduction in intraocular pressure (IOP) compared with the standard titrated approach at up to 36 months postprocedure.

Purpose:
There is no consensus on ideal SLT procedural laser energy settings. This study aims to compare fixed high-energy SLT to the standard titrated-energy approach within the setting of a residency training program.

Patients:
Patients over the age of 18 years received SLT between 2011 and 2017, a total of 354 eyes. Patients with a prior history of SLT were excluded.

Methods:
Retrospective review of clinical data from 354 eyes that underwent SLT. Eyes that underwent SLT using fixed high energy (1.2 mJ/spot) were compared with those with the standard titrated approach starting at 0.8 mJ/spot and titrating to “champagne” bubbles. The entirety of the angle was treated using a Lumenis laser set to the SLT setting (532 nm). No repeat treatments were included.

Main Outcome Measure:
IOP and glaucoma medications.

Results:
In our residency training program, fixed high-energy SLT was associated with a reduction in IOP compared with a baseline of −4.65 (±4.49, n = 120), −3.79 (±4.49, n = 109), and −4.40 (±5.01, n =119) while standard titrated-energy was associated with IOP reduction of −2.07 (±5.06, n = 133), −2.67 (±5.28, n = 107), and −1.88 (±4.96, n = 115) at each respective postprocedural time point (12, 24, and 36 months). The fixed high-energy SLT group had significantly greater IOP reduction at 12 months and 36 months. The same comparison was performed for medication naïve individuals. For these individuals, fixed high-energy SLT resulted in IOP reductions of −6.88 (±3.72, n = 47), −6.01 (±3.80, n = 41), and −6.52 (±4.10, n = 46) while standard titrated-energy had IOP reductions of −3.82 (±4.51, n = 25), −1.85 (±4.88, n = 20), and −0.65 (±4.64, n = 27). For medication naïve individuals, fixed high-energy SLT resulted in a significantly greater reduction in IOP at each respective time point. Complication rates (IOP spike, iritis, and macular edema) were similar between the two groups. The study is limited by overall poor response to standard-energy treatments, whereas high-energy treatments showed similar efficacy to those in literature.

Conclusion:
This study demonstrates that fixed-energy SLT produces at least equivalent results compared with the standard-energy approach, without an increase in adverse outcomes. Particularly in the medication naïve subpopulation, fixed-energy SLT was associated with a significantly greater IOP reduction at each respective time point. The study is limited by overall poor response to standard-energy treatments, with our results showing decreased IOP reduction compared with those of previous studies. These poor outcomes of the standard SLT group may be responsible for our conclusion that fixed high-energy SLT results in a greater reduction in IOP. These results may be useful when considering optimal SLT procedural energy in future studies for validation.