A Trial to Compare the Laser Treatment (SLT vs. ALT) in Glaucoma Patients (SLTRepeat)

A Randomized Clinical Trial of Selective Laser Trabeculoplasty (SLT) in Open Angle Glaucoma Who Had Been Previously Treated With Complete SLT

Lasers are important therapy in glaucoma. They are a pivotal point in treatment between medical and surgical care. Over the last 10 years a new laser has emerged as the usual laser treatment: Selective laser trabeculoplasty (SLT). SLT works as well as the older laser used: argon laser trabeculoplasty (ALT). However SLT has many theoretical benefits over ALT including causing less damage to the tissue it affects. One of the potential patient centered benefits of this laser is that it may be repeatable. It is even possible that the old laser ALT may be useable after an SLT treatment. This study aims to uncover whether repeat laser is possible after SLT and if so which laser is more effective (ALT vs SLT). The potential of repeating laser therapies may delay surgical treatment and its complications. Also understanding which laser to use will help eye doctors know how to treat their patients at this point of the disease.

Up to the year 2005, the vast majority of ophthalmologists used Argon laser trabeculoplasty (ALT) as the mode of laser therapy. ALT is effective but its most significant problem is that its effectiveness decreases with re-treatment since the tissue it targets (the trabecular meshwork) is changed by the laser rendering repeat treatments less effective.

Post 2005, a newer mode of laser therapy, selective laser trabeculoplasty (SLT) has emerged as the standard of care laser. There are many potential advantages to SLT but to date these advantages are only theoretical. The most important potential clinical advantage of SLT is that it causes less damage to the tissue it targets.

With Argon laser trabeculoplasty (ALT), thermal energy is used directed towards the Trabecular Meshwork (the site of aqueous drainage from the eye),which causes focal scarring of trabecular meshwork, thus enable fluid drainage more effectively. However, this procedure may not be repeatable since it causes too much damage to the trabecular meshwork.

Selective laser trabeculoplasty is a relatively newer technology that uses a Nd:YAG laser to target specific cells within the trabecular meshwork. SLT does not cause coagulative damage to the trabecular meshwork, and thus has the advantage of being repeatable.

Inclusion Criteria: Over age of 18 yo. OAG including pigmentary dispersion syndrome and pseudoexfoliation OAG has been treated with 360 degrees of SLT two sighted eyes, willing to participate after being informed of and reading the patient information material. Exclusion Criteria: Narrow angle glaucoma Previous glaucoma surgery Eye surgery expected in the next 12 months Severe corneal disease On or anticipated steroid in 6 months Pregnant or breast feeding

Rolim-de-Moura CR, Paranhos A Jr, Loutfi M, Burton D, Wormald R, Evans JR. Laser trabeculoplasty for open-angle glaucoma and ocular hypertension. Cochrane Database Syst Rev. 2022 Aug 9;8(8):CD003919. doi: 10.1002/14651858.CD003919.pub3.

Hutnik C, Crichton A, Ford B, Nicolela M, Shuba L, Birt C, Sogbesan E, Damji KF, Dorey M, Saheb H, Klar N, Guo H, Hodge W. Selective Laser Trabeculoplasty versus Argon Laser Trabeculoplasty in Glaucoma Patients Treated Previously with 360 degrees Selective Laser Trabeculoplasty: A Randomized, Single-Blind, Equivalence Clinical Trial. Ophthalmology. 2019 Feb;126(2):223-232. doi: 10.1016/j.ophtha.2018.09.037. Epub 2018 Sep 29.