Abstract
Purpose: :
Given the relatively recent development of Selective Laser Trabeculoplasty (SLT), tremendous inter–operator variability in treatment parameters has occurred without much evidence to support a particular dose response. In an attempt to fill this void, we retrospectively compared intraocular pressure (IOP) response, glaucoma medication usage, and re–treatment rates among open–angle glaucoma patients who underwent either 180°, 270° or 360° of Selective Laser Trabeculoplasty (SLT) of their trabecular meshwork (TM).
Methods: :
In a retrospective chart review of 51 patients, the authors compared the IOP response of SLT in 3 groups: group 1 received SLT treatment over 180° of TM, group 2 received treatment over 270° of TM, and group 3 received treatment over 360° of TM. Post–operative IOP and adjunctive glaucoma medication up to 1 year of follow–up, as well as SLT re–treatment rates by the end of a 2 follow–up period were the main outcome measures.
Results: :
1 year post–operatively, significant mean IOP reductions of 3.8, 3.1 and 3.0 mmHg were determined for each of the groups receiving 180°, 270° or 360° of SLT respectively. However multivariate analysis showed that these reductions were not statistically different from each other (P=0.86). Although the study confirmed the IOP–lowering efficacy of SLT, at 1 year there was neither a significant decrease in the number of glaucoma medications used within, nor among each of the three groups (P=0.75). Finally, it was determined that at the end of a 2 year follow–up period, 33% of the 180° treated patients had undergone a second round of SLT, compared to none in the 270° group, and 11% in the 360° group (P>0.05). The re–treatment rate of the 180° group was statistically higher than the other two groups only when considering patients with primary and normotensive open–angle glaucoma subtypes (P=0.025).
Conclusions: :
SLT treatment of 180°, 270° or 360° of trabecular meshwork resulted in statistically similar intraocular pressure reduction and did not appear to lower the number of glaucoma medications used 1 year after the initial procedure. Among primary open–angle and normal–tension glaucoma patients, the smaller treatment area of 180° in our study increased the likelihood of needing repeat SLT treatment to reach target intraocular pressure.
Keywords: laser • trabecular meshwork • intraocular pressure