Impact of laser pulse duration on the reduction of intraocular pressure during selective laser trabeculoplasty.

Abstract

To evaluate the efficacy of selective laser trabeculoplasty (SLT) to lower intraocular pressure (IOP) in patients with primary open-angle glaucoma (POAG), normal tension glaucoma (NTG) or ocular hypertension (OHT), when performed with laser pulse duration of 1ns compared with standard 3-5ns. Bilateral SLT with a 532nm Q-switched neodymium-doped yttrium aluminium garnet laser was conducted in 30 patients (60 eyes) with POAG (n=5), NTG (n=2) or OHT (n=23). Pulse duration was 1ns in the right eye (30 eyes; cases) and 3-5ns in all left eyes (controls). Main outcome measures were IOP at 1h, 1day, 8weeks and 6months, and the rate of adverse ocular tissue reactions in all eyes. Mean 1ns and 3-5ns SLT IOPs were 24.1 and 24.3mmHg, respectively, at baseline. No statistically significant difference in mean 1ns and 3-5ns SLT IOP was observed at 1h (P=0.761), 1day (P=0.758), 8weeks (P=0.352) and 6months postoperatively (P=0.879). No significant difference in postoperative anterior chamber inflammation was observed between the eyes (P=0.529). Treatment with both laser pulse durations resulted in minor ultrastructural changes in the drainage angle. SLT performed with a 1ns laser pulse duration does not appear to be inferior to SLT performed with the standard 3-5ns duration at lowering IOP in treatment-naïve patients with POAG, NTG or OHT.