Efficacy Of Selective Laser Trabeculoplasty After Trabecular Meshwork Microbypass Stent Placement In Pseudophakic Patients With Open Angle Glaucoma

Trabecular meshwork microbypass stents (Glaukos iStent) and selective laser trabeculoplasty (SLT) augment trabecular outflow to lower intraocular pressure (IOP) in patients with open-angle glaucoma (OAG). However, the interaction between these two IOP-lowering modalities has not been well characterized. Previous work from a single center in the United States demonstrated that SLT lowered IOP in both patients who did and did not receive iStent placement; however, iStent did not augment the IOP-lowering effect of SLT. This study did not control for pseudophakia, which is known to independently lower IOP. Our study aims to characterize the efficacy of SLT after iStent placement in pseudophakic patients with POAG.

A retrospective cohort study from a single surgeon in the United States.

A retrospective chart review was performed on 69 pseudophakic eyes (47 patients) and 69 pseudophakic eyes with iStents (41 patients) that underwent SLT. Age at the time of SLT, race, sex, laterality, baseline best corrected visual acuity (BCVA), central corneal thickness (CCT), presence of pigmentary glaucoma or pseudoexfoliation syndrome (PXE), concurrent minimally invasive glaucoma surgery (MIGS) with iStent placement, number of ocular hypotensive medications before and after SLT, mean medicated IOP in the 3 months prior to SLT, and medicated IOP up to 36 months after SLT were collected. The primary outcome was the difference in IOP before SLT and 2 months after SLT.

SLT decreased mean medicated IOP in both patients with and without iStents at 2 months (p=0.001, p=0.0003), but not 18 months (p<0.0001, p=0.07). There was no difference in mean IOP before or after SLT in patients without and with iStents (16.3 vs 15.6, p=0.16) at 2 months (13.9 vs 13.2, p=0.33) and 18 months (14.7 vs 14.5, p=0.73) after SLT. There was no difference in the percentage of patients who achieved >20% reduction in IOP between the two groups at 2 months (32.5% vs 38.2%, p = 0.79) and 18 months (20.0% vs 18.9%, p = 0.97). The mean number of medications after SLT in the iStent group was comparable at baseline (1.52 vs 1.15, p=0.07) and at 2 months (1.44 vs 1.12, p=0.03), but was higher at 18 months (1.73 vs 1.32, p = 0.04).

SLT is effective in decreasing mean-medicated IOP in pseudophakic patients, regardless of the presence of trabecular microbypass stents. Clinicians can counsel patients to consider SLT as an effective therapy after iStent implantation in terms of reducing mean-medicated IOP; however, clinicians should be aware that the presence of an iStent does not make SLT more effective at lowering IOP.