In the selective laser trabeculoplasty (SLT) mechanism, the 532 nm Q-switched Nd:YAG laser selectively targets which cells in the trabecular meshwork?

• A Endothelial cells of Schlemm's canal
• B Pigmented trabecular meshwork cells (melanin-containing cells) ✓
• C Juxtacanalicular connective tissue cells
• D Uveal meshwork cells

Explanation

SLT selectively targets melanin-containing (pigmented) trabecular meshwork cells using short pulse durations (3 nanoseconds) at 532 nm wavelength. The short pulse duration confines thermal damage to pigmented cells only, avoiding collateral thermal injury to adjacent non-pigmented cells — this is the principle of selective photothermolysis. The biological response involves macrophage recruitment and cytokine-mediated remodeling of trabecular meshwork architecture, ultimately improving aqueous outflow. This contrasts with ALT (argon laser trabeculoplasty), which causes coagulative damage to all tissues.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.