Prospective study on the efficacy of treating normal tension glaucoma with a single session of selective laser trabeculoplasty

Abstract

PURPOSE: The purpose of this study was to investigate the efficacy of selective laser trabeculoplasty (SLT) in the treatment of normal tension glaucoma (NTG). METHODS: This prospective cohort study recruited consecutive cases of NTG on antiglaucoma medication. Cases were excluded for previous glaucoma surgery or laser. All patients underwent a 1-month washout of medication followed by a mean baseline intraocular pressure (IOP) measured at 9 AM, 1 PM, and 5 PM. A 30% reduction from baseline was set as the target IOP. A single session of SLT was performed to 360 degrees of the trabecular meshwork. IOP phasing was repeated at 1 month after SLT and medication was resumed to achieve the target IOP. Patients were followed up to 6 months after SLT. RESULTS: In 83 eyes of 46 subjects, the mean prestudy IOP was 14.2 ± 3.1 mm Hg when on 1.5 ± 0.9 antiglaucoma medication. The mean baseline IOP without medication was 16.1 ± 2.2 mm Hg. The mean SLT shots applied was 187.8 ± 27.5 using a mean energy of 1.0 ± 0.07 mJ. At 1-month post-SLT, the IOP was 12.7 ± 2.0 mm Hg (21.6% IOP reduction) from baseline without medication (P<0.05). The 6-month IOP was 11.4 ± 1.6 mm Hg when on 1.1± 1.0 medications, representing a 19.7% reduction from prestudy IOP, a 29.6% reduction from baseline IOP, and a 26.7% reduction in antiglaucoma medication (all P< 0.05). A higher baseline IOP was correlated with greater IOP reduction with SLT (r=0.3, P=0.009). CONCLUSIONS: A single session of SLT for NTG achieved an additional 20% reduction in IOP with 27% less medication at 6 months compared with prestudy levels while maintaining a 30% reduction from baseline IOP.