Pillunat and colleagues have conducted a prospective interventional case series to evaluate the role of selective laser trabeculoplasty (SLT) in reducing 24-hr circadian IOP fluctuations in eyes with primary open-angle glaucoma (POAG) uncontrolled on maximum- tolerated medical therapy (MTMT). Overall, 157 eyes of 157 subjects underwent 360-degree SLT (~100 spots). IOP was measured at 1PM, 4PM, 7PM, 10PM, midnight, and 7AM before and six months after SLT; medication regimens were unchanged during this time to isolate the SLT effect. Mean 24-hr IOP was reduced from 15.1 mmHg to 13.8 mmHg (p < 0.001), and mean 24-hour fluctuations were reduced from 6.5 mmHg to 5.4 mmHg (p < 0.001). The authors concluded that adjunctive SLT lowers both mean 24-hr IOP and 24-hr IOP fluctuations in medically treated patients with POAG. These findings are consistent with similar prior reports. However, the magnitude of effect in this study was small and may represent an underestimation of SLT's effects on IOP and IOP fluctuations when used earlier in the treatment cascade to mirror an ongoing paradigm shift away from the traditional medication-first approach to glaucoma care. Key studies such as the SLT/MED study and the more recent LiGHT study have demonstrated that SLT is at least as effective as, and likely more so than, medical therapy as first-line treatment for POAG, and the ongoing NIH-supported COAST trial is exploring innovative approaches to SLT utilization to optimize medication-free survival when used as primary therapy.
Reserving SLT as fourth-, fifth-, or sixth-line therapy when MTMT fails represents a missed opportunity to utilize this treatment option as first-line therapy where it performs best
Reserving SLT as fourth-, fifth-, or sixth-line therapy when MTMT fails represents a missed opportunity to utilize this treatment option as first-line therapy where it performs best. An additional comment regarding the study design of this trial: IOP fluctuations were defined as the highest IOP minus the lowest IOP of the 6 measurements over 24 hours. As these by definition are the two most outlying values, the potential for mischaracterization of IOP variability is high. An alternative parameter to characterize IOP variability ? the standard deviation of all 6 measurements ? is more robust both because it avoids reliance on the two most outlying values and it utilizes all of the data points. These critiques aside, this study demonstrates that, in eyes with POAG uncontrolled on MTMT, SLT can produce statistically significant reductions in both mean IOP and IOP fluctuations and is likely a reasonable intervention to undertake before the next logical step, which is incisional surgery.