Efficacy of Repeat Selective Laser Trabeculoplasty in Medication-Naive Open-Angle Glaucoma and Ocular Hypertension during the LiGHT Trial

Abstract

Purpose: To determine the efficacy of repeat selective laser trabeculoplasty (SLT) in medication-naive open-angle glaucoma (OAG) and ocular hypertensive (OHT) patients requiring repeat treatment for early to medium-term failure during the Laser in Glaucoma and Ocular Hypertension (LiGHT) trial.

Design: Post hoc analysis of SLT treatment arm of a multicenter prospective randomized controlled trial.

Participants: Treatment-naive OAG or OHT requiring repeat 360-degree SLT within 18 months. Retreatment was triggered by predefined IOP and disease-progression criteria (using objective individualized target IOPs).

Methods: After SLT at baseline, patients were followed for a minimum of 18 months after second (repeat) SLT. A mixed-model analysis was performed with the eye as the unit of analysis, with crossed random effects to adjust for correlation between fellow eyes and repeated measures within eyes. Kaplan-Meier curves plot the duration of effect.

Main outcome measures: Initial (early) IOP lowering at 2 months and duration of effect after initial and repeat SLT.

Results: A total of 115 eyes of 90 patients received repeat SLT during the first 18 months of the trial. Pretreatment IOP before initial SLT was significantly higher than before retreatment IOP of repeat SLT (mean difference, 3.4 mmHg; 95% confidence interval [CI], 2.6-4.3 mmHg; P < 0.001). Absolute IOP reduction at 2 months was greater after initial SLT compared with repeat SLT (mean difference, 1.0 mmHg; 95% CI, 0.2-1.8 mmHg; P = 0.02). Adjusted absolute IOP reduction at 2 months (adjusting for IOP before initial or repeat laser) was greater after repeat SLT (adjusted mean difference, -1.1 mmHg, 95% CI, -1.7 to -0.5 mmHg; P = 0.001). A total of 34 eyes were early failures (retreatment 2 months after initial SLT) versus 81 later failures (retreatment >2 months after initial SLT). No significant difference in early absolute IOP reduction at 2 months after repeat SLT was noted between early and later failures (mean difference, 0.3 mmHg; 95% CI, -1.1 to 1.8 mmHg; P = 0.655). Repeat SLT maintained drop-free IOP control in 67% of 115 eyes at 18 months, with no clinically relevant adverse events.

Conclusions: These exploratory analyses demonstrate that repeat SLT can maintain IOP at or below target IOP in medication-naive OAG and OHT eyes requiring retreatment with at least an equivalent duration of effect to initial laser.