Clinical outcomes of trabecular microbypass stent (iStent®) implantation in medically controlled open‐angle glaucoma in the Korean population

Abstract

PurposeTo evaluate the safety and efficacy [intraocular pressure (IOP)‐lowering effect and medication use] of a single trabecular microbypass stent (iStent®; Glaukos Corp., San Clemente, CA, USA) for medically controlled open‐angle glaucoma.MethodsThis retrospective case‐series included 42 eyes of 34 patients with medically controlled open‐angle glaucoma with IOP less than 21 mmHg. Clinical outcomes analyzed were IOP, medication use, corrected distance visual acuity (CDVA), and surgical complications. Surgical success was defined according to three criteria: (A) IOP <21 mmHg without medication; (B) IOP <18 mmHg without medication; and (C) IOP <18 mmHg with or without medication. Patients were followed for a minimum of six months postoperatively.ResultsMean IOP was reduced from 15.8 ± 2.8 mmHg to 14.5 ± 2.8 mmHg (p < 0.001), while mean number of medications decreased from 2.2 ± 1.2 to 0.8 ± 1.1 at final visit (p < 0.001). Surgical success rates were 78.6%, 61.9%, and 97.6% at six months and 78.6%, 59.5%, and 95.2% at final visits according to criteria A, B, and C. Meanwhile, 59.5% of patients were medication‐free at their final visit. The relative risk of surgical failure by Criterion B was 4.337 (95% confidence interval:1.799–10.454) times greater in the higher‐medication group (three or more preoperative medications). CDVA was significantly improved from 0.41 ± 0.10 to 0.09 ± 0.07 LogMAR in the combined phacoemulsification and iStent® implantation group (p < 0.001). There was no case whose vision was threatened (vision loss of two or more lines) or who showed severe complications after surgery.ConclusionsSingle trabecular microbypass stent implantation was effective in reducing IOP and medication usage in patients with open‐angle glaucoma with a low preoperative IOP. Our results imply that it is more difficult to achieve low target IOP control in eyes with higher numbers of preoperative medications.