SLT and ALT seem to have similar efficacy in lowering IOP. Approximately 80% of patients with medically uncontrolled OAG experience a drop in IOP for at least 6 months following LTP. Among patients who had an initial response, 50% maintain a significantly lower IOP level for 3–5 years after treatment. The success rate at 10 years is about 30%. Higher success rates are seen in older patients with primary open-angle glaucoma (POAG) and pseudoexfoliative glaucoma.
Treatment can be repeated with SLT and MLT, although success rates seem to decline with each subsequent treatment. Because the initial ALT treatment is usually applied to only 180° of the trabecular meshwork, the laser can be applied to the untreated half of the meshwork later, if needed. However, in previously treated areas, repeat ALT may be less effective and associated with an increased risk of IOP elevation. SLT can be used in areas of prior ALT treatment, with results similar to those in eyes undergoing repeat SLT. LTP is less effective in patients with angle-recession glaucoma, inflammatory glaucoma, or abnormal angle structure.
The Glaucoma Laser Trial (GLT) was a multicenter randomized clinical trial that assessed the efficacy and safety of ALT as an alternative to topical medical therapy in patients with newly diagnosed, previously untreated POAG. As initial therapy, ALT appeared to be at least as effective as medication in reducing IOP, preventing visual field loss, and slowing an increase in cup–disc ratio. The study was flawed in that 1 eye was assigned to ALT while the fellow eye was assigned to timolol treatment, which can have an IOP-lowering effect on the contralateral eye, potentially confounding the results. More than half of the eyes treated initially with laser required the addition of 1 or more medications to control IOP over the course of the study.
The Laser in Glaucoma and Ocular Hypertension (LiGHT) Trial was a prospective randomized study that compared SLT to medical treatment in the initial management of ocular hypertension and glaucoma. At 36 months, IOP control was similar between the 2 groups, while SLT was more cost-effective. Patients who had SLT scored similarly or better on quality-of-life measures compared with patients using medication.
Gazzard G, Konstantakopoulou E, Garway-Heath D, et al; LiGHT Trial Study Group. Selective laser trabeculoplasty versus eye drops for the first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial. Lancet. 2019;393(10180):1505–1516.
Glaucoma Laser Trial Research Group. The Glaucoma Laser Trial (GLT) and Glaucoma Laser Trial Follow-up Study: 7. Results. Am J Ophthalmol. 1995;120(6):718–731.
Hutnik C, Crichton A, Ford B, et al. Selective laser trabeculoplasty versus argon laser trabeculoplasty in glaucoma patients treated previously with 360° selective laser trabeculoplasty: a randomized, single-blind, equivalence clinical trial. Ophthalmology. 2019;126(2):223–232.
Wang W, He M, Zhou M, Zhang X. Selective laser trabeculoplasty versus argon laser trabeculoplasty in patients with open-angle glaucoma: a systematic review and meta-analysis. PLoS One. 2013;8(12):E84270.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.