Selective Laser Trabeculoplasty: Outcomes of Multiple Repeat Treatments.

PURPOSE: To characterize intraocular pressure (IOP) reduction, effect duration, and side effect profile of repeat selective laser trabeculoplasty (SLT) used as primary stand-alone treatment for open-angle glaucoma (OAG). The secondary aim was to investigate covariates associated with treatment response to SLT. DESIGN: Retrospective chart review. PARTICIPANTS: A total of 52 patients with treatment-naïve OAG who received 3 installments of 3600 SLT as stand-alone glaucoma therapy. When both eyes met the inclusion criteria, only right eye data were used for analysis. METHODS: The study was conducted in a single specialist practice. First, second, and third SLT (SLT1, SLT2, SLT3, respectively) treatments were compared for IOP reduction and effect duration. Eyes were classified as "treatment responders" if they had ≥20% IOP reduction 4 to 8 weeks post-SLT compared with baseline. Effect duration was the interval between SLT and the time point at which the surgeon decided inadequate IOP control necessitated repeat SLT. Individuals were excluded if they underwent intraocular surgery during the study period or received treatment with adjunctive ocular hypotensive medications. MAIN OUTCOME MEASURES: Reduction in IOP post-SLT and effect duration between treatments. RESULTS: Mean age at SLT1 was 58 years; 50% were male, and 92% were phakic. The SLT1 and SLT3 both resulted in mean 27% IOP reduction at 4 to 8 weeks, whereas SLT2 led to 26% IOP reduction. Response rate (≥20% IOP reduction at 4-8 weeks) was 79% for SLT1, 73% for SLT2, and 81% for SLT3, but the difference was not statistically significant. Response to repeat SLT was not significantly associated with previous SLT outcome. Effect duration was 22.2 months, 33.8 months, and 28.9 months after SLT1, SLT2, and SLT3, respectively. Effect duration was significantly longer after SLT2 (P = 0.0006) and SLT3 (P = 0.0444) compared with SLT1. There was no significant association between SLT response and gender, lens status, or OAG subtype. CONCLUSIONS: For primary stand-alone treatment in OAG, initial and repeat SLTs produced comparable percentage IOP reduction, but repeat SLTs had longer effect duration. Intraocular pressure response to SLT was not predictive of the IOP response to subsequent, repeat SLT treatment.

A review of aqueous outflow resistance and its relevance to microinvasive glaucoma surgery.

Primary open-angle glaucoma is the leading cause of irreversible blindness worldwide, and intraocular pressure reduction remains the only proven treatment strategy. Elevated intraocular pressure occurs as the result of impaired aqueous humor outflow. Both a passive model and a dynamic model have been used to explain trabecular outflow resistance. The passive model posits that the trabecular meshwork acts as a static filter that exerts stable and passive resistance to outflow. In contrast, the dynamic model involves a "biomechanical pump." In recent years, the range of surgical management options for glaucoma has dramatically expanded, particularly the class of procedures known as microinvasive glaucoma surgery. These procedures typically target and enhance specific outflow routes. Optimal patient outcomes with microinvasive glaucoma surgery require a clear understanding of aqueous outflow and a surgical approach that is targeted to overcome the site of abnormal resistance in the individual. We review the anatomy and physiology of trabecular and suprachoroidal outflow that is of relevance to microinvasive glaucoma surgery-performing surgeons.