Association between prior selective laser trabeculoplasty and phaco-iStent inject efficacy

Background: To evaluate the association between prior selective laser trabeculoplasty (SLT) on intraocular pressure (IOP) lowering efficacy of phacoemulsification combined with iStent inject (phaco-iStent). Methods: Retrospective study of 1550 eyes of 1023 patients with and without prior SLT that underwent phaco-iStent. Surgical success was defined at 12 months using three different endpoints: (A) IOP ≤ 21 mmHg and ≥ 20% IOP decrease, or ≥ 1 medication reduction vs. baseline, (B) ≥ 1 medication reduction with no increase in baseline IOP or (C) IOP ≤ 21 mmHg and ≥ 20% IOP decrease alone with no increase in baseline medication use. The prior SLT and no SLT patients were propensity score matched by age, baseline IOP and IOP-lowering medication use and visual field mean deviation (VF MD). Results: Three hundred and sixty-eight eyes (184 eyes per group) of 313 patients were matched based on baseline IOP and medications, VF MD, and age at surgery. Prior SLT was associated with an increased risk of failure using endpoints A [hazards ratio (HR) 2.13, 95% confidence intervals (CI) 1.34—3.38], B (HR 1.73, CI 1.1—2.72) and C (HR 1.51, CI 1.05—2.16). In eyes with prior SLT, higher baseline IOP was significantly associated with a lower risk of failure to achieve a minimum 20% reduction in IOP from baseline (HR 0.89, 0.85—0.94, p < 0.001). Conclusion: In this observational study, prior SLT was associated with an increased risk of failure after phaco-iStent inject surgery. In eyes with prior SLT, there was a significantly decreased risk of failure in eyes with higher baseline IOP.