Dear Editor

Dear Dr Bastawrous,
In answer to the question: "What specifically makes SLT different from ALT in its action?" we offer the following response:

The mechanical theory of IOP reduction in argon laser trabeculoplasty (ALT) proposes that a thermal burn contracts tissue and stretches open those adjacent, untreated regions of the trabecular meshwork (TM) to increase outflow. However, in SLT, disruption or death of pigmented TM cells alone appears to induce a response that results in IOP reduction.

Previous clinical trials comparing ALT to SLT showed SLT to have equal or more favourable outcomes. However, SLT was better tolerated and produced less discomfort compared with ALT.

Suggested reading: M.A. Latina & J.M. deLeon. Selective Laser Trabeculoplasty. Ophthalmol. Clin. N. Am. 2005;409-419.

Arusha Gupta
SUNY Stony Brook School of Medicine, Stony Brook, New York, USA

Lawrence F. Jindra, MD
Columbia University, New York, USA