Selective Laser Trabeculoplasty (SLT)

A frequency-doubled Nd:YAG laser selectively targets pigmented trabecular meshwork cells to enhance aqueous outflow and safely lower intraocular pressure in glaucoma — a repeatable, non-incisional procedure.

Selective Laser Trabeculoplasty (SLT) is a first-line laser intervention for open-angle glaucoma. The 532 nm frequency-doubled Nd:YAG laser exploits selective photothermolysis to target pigmented cells within the trabecular meshwork, triggering a biological cascade of cytokine release and macrophage infiltration that improves aqueous outflow facility and lowers IOP. Because each laser pulse is only 3 nanoseconds long, thermal diffusion is negligible; surrounding non-pigmented cells and trabecular architecture are preserved. This distinguishes SLT from traditional argon laser trabeculoplasty (ALT) — SLT causes less collateral damage and can be repeated. SLT typically reduces IOP by 20-30%. Effect onset is approximately 4-6 weeks post-treatment, and duration varies considerably (1-5 years). When the effect wanes, SLT can be repeated, which is its main advantage over ALT. SLT may serve as first-line therapy replacing topical IOP-lowering drops (supported by several major guidelines) or as adjunctive treatment when medications are inadequate, deferring or avoiding incisional surgery. The procedure is performed at the slit lamp using a goniolens and requires no hospitalization, making it one of the most accessible interventions for glaucoma management.