Selective laser trabeculoplasty (SLT) differs from argon laser trabeculoplasty (ALT) in mechanism because SLT:

• A Applies thermal burns to the trabecular meshwork to create new drainage channels
• B Uses a frequency-doubled Nd:YAG laser selectively absorbed only by melanin-containing cells, sparing adjacent non-pigmented cells ✓
• C Increases uveoscleral outflow by creating cyclodialysis clefts
• D Uses argon wavelength to photocoagulate the ciliary body reducing aqueous production

Explanation

SLT uses a Q-switched, frequency-doubled Nd:YAG laser (532 nm, 3 ns pulse duration) with low energy that is selectively absorbed by the melanin in trabecular meshwork pigmented cells (photothermolysis), sparing adjacent non-pigmented cells and collagen beams. This selectivity is the key difference from ALT, which thermally coagulates and scars the trabecular meshwork. Because SLT does not produce structural damage, it can be repeated if the IOP-lowering effect diminishes. The LiGHT trial (UK) found SLT as effective as initial medical therapy for newly diagnosed POAG/OHT, with 74% treatment-naive SLT patients not requiring additional drops at 3 years.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.