Mid to Long-Term Outcomes of Low-Energy Selective Laser Trabeculoplasty for Primary Open Angle Glaucoma

Background/Objectives: To evaluate the mid- to long-term outcomes of selective laser trabeculoplasty (SLT) performed with lower energy (≤0.5 millijoules (mJ)) than conventional settings (0.6-1.2 mJ). Methods: This retrospective chart-review study included patients who underwent low-energy SLT (0.34 ± 0.06 mJ) at Shimane University Hospital from April 2018 onward. A total of 54 patients (99 eyes) were analyzed, with a mean follow-up period of 57.5 months and a maximum follow-up period of 114 months. Treatment failure was defined using two criteria: an increase in the number of medications or the addition of incisional glaucoma surgery, and the addition of incisional glaucoma surgery. Kaplan-Meier survival analyses and multivariate Cox proportional hazards models were performed to evaluate long-term outcomes and prognostic factors. Results: During the follow-up period, 54 eyes underwent a single SLT treatment. A total of 37 eyes underwent two SLT treatments, and 8 eyes underwent three treatments. Mean intraocular pressure (IOP) significantly decreased from 16.7 mmHg at baseline to 15.1, 14.4, and 13.9 mmHg at 12, 36, and 60 months, respectively (mixed-effects model, p < 0.0001). Medication scores were 2.2, 2.3, 2.1, and 2.8 at baseline, 12, 36, and 60 months, respectively (p = 0.0006). Success rates at 12, 36, and 60 months were 72%, 37%, and 26% by Definition 1, and 90%, 69%, and 61% by Definition 2. At 36 months, success rates stratified by baseline medication score (0, 1-2, and ≥3) were 11%, 50%, and 38% for Definition 1 (p = 0.0002), and 83%, 75%, and 58% for Definition 2 (p = 0.02). Under Definition 1, more than 90% of eyes in the medication-free group required additional medications or surgery within 5 years. Under Definition 2, 60% of eyes with a preoperative medication score of ≥3 required surgeries within 5 years. Conclusions: Performing low-energy SLT in patients using approximately one medication can delay the need for additional therapy or surgery while maintaining IOP reduction over the observation period.