The mechanism by which selective laser trabeculoplasty (SLT) lowers IOP differs from argon laser trabeculoplasty (ALT) in that SLT:

• A Thermally coagulates trabecular meshwork cells causing physical opening of Schlemm's canal
• B Selectively targets pigmented trabecular cells via photomechanical disruption stimulating macrophage recruitment and biological remodeling ✓
• C Permanently seals collector channels to redirect aqueous to uveoscleral pathway
• D Causes contracture of scleral spur increasing conventional outflow

Explanation

SLT uses a Q-switched Nd:YAG laser (532 nm) that is selectively absorbed by melanin in pigmented trabecular meshwork cells, causing photomechanical (not thermal) disruption. This triggers macrophage recruitment and biological remodeling of the trabecular meshwork, improving aqueous outflow without causing collateral thermal damage. ALT, by contrast, causes thermal coagulation and scarring, which limits repeatability. SLT can be repeated because it does not cause significant scarring.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.