SLT considered safer alternative to ALT

October 24, 2004

Selective laser trabeculoplasty (SLT) utilizing a short-pulse, low-energy (532 nm) laser (Selecta Duet, Lumenis) is a safe and effective treatment option for patients with open-angle glaucoma. This approach offers good IOP lowering and control while preserving the trabecular meshwork architecture, said its developer, Mark A. Latina, MD.

New Orleans-Selective laser trabeculoplasty (SLT) utilizing a short-pulse, low-energy (532 nm) laser (Selecta Duet, Lumenis) is a safe and effective treatment option for patients with open-angle glaucoma. This approach offers good IOP lowering and control while preserving the trabecular meshwork architecture, said its developer, Mark A. Latina, MD.

Prior to the introduction of SLT, argon laser trabeculoplasty (ALT) had been utilized for lowering IOP in patients who had a poor response to medical therapy in the 1980s.

"Then, the Glaucoma Laser Trial was undertaken and showed that ALT could be used effectively in lowering IOP as primary therapy in patients with primary open-angle glaucoma," said Dr. Latina, who spoke during a breakfast session held by Lumenis during the American Academy of Ophthalmology annual meeting. "During that time we were developing a sense of what ALT was all about. We knew that there were post-treatment increases in IOP, PAS formation, some cases of chronic inflammation, limited efficacy of ALT re-treatment, and histology studies showed that there was coagulative damage to the trabecular meshwork."

From his research, Dr. Latina noted that photocoagulation is not necessary to reduce IOP. So the trabecular meshwork didn't have to be burned to reduce IOP.

SLT was developed to selectively target trabecular meshwork cells without producing any structural or coagulative damage, noted Dr. Latina, associate clinical professor of ophthalmology, Tufts University Medical School, and associate surgeon at the Massachusetts Eye and Ear Infirmary, Boston. "It targets melanin within the trabecular meshwork cell and doesn't cause any thermal damage to the surrounding tissues."

The SLT laser was tested in preclinical trials using OWL monkeys and shown to not produce an IOP increase postoperatively and there was no evidence of thermal damage, he said.

SLT and ALT offer equivalent IOP results, according to Joel Schuman, MD, who spoke about the various published studies of SLT. He showed a reduction in IOP of between 20% to 40% using SLT technology.

A prospective, randomized trial (SLT/MED Study) is now being undertaken to determine the efficacy of SLT as first-line therapy compared with medical therapy. Fifteen sites in the United States and one site in Canada are participating. The study will enroll up to 600 eyes and follow them for 18 months. The patient decides on medical therapy first or laser treatment first.

"Both eyes are treated with SLT within 2 weeks using a 360-degree treatment and 100 pulses," said Dr. Schuman, the Eye and Ear Foundation Professor and Chairman of Ophthalmology, University of Pittsburgh School of Medicine. "If IOP is not maintained over 4 to 6 weeks, we will repeat the SLT with 50 pulses over 180 degrees."

Jay Katz, MD, is the principle investigator and Dr. Schuman is the co-investigator.

Monte Dirks, MD, a private practitioner in Rapid City, SD, spoke about integrating the SLT system into one's practice.