One-year analysis of the iStent trabecular microbypass in secondary glaucoma

Purpose: To evaluate the midterm efficacy and safety of the iStent (R) glaucoma device in patients with secondary open-angle glaucoma. Patients and methods: A prospective, nonrandomized, interventional case series involving 10 patients with secondary open-angle glaucoma (traumatic, steroid, pseudoexfoliative, and pigmentary glaucoma) of recent onset who underwent ab interno implantation iStent. Patients were assessed following the procedure on days 1, 7, and 15 and months 1, 3, 6, and 12, and examinations included visual acuity, intraocular pressure (IOP) measurement using Goldmann tonometry, number of glaucoma medications, and complications. Wilcoxon rank-test for data with abnormal distribution was used for the analysis of IOP and glaucoma medications at baseline versus 3, 6, and 12 months following the procedure. Results: The mean baseline IOP was 26.5 +/- 7.9 (range 18-40) mmHg, and significantly decreased in 10.4 +/- 9.2 mmHg at three months (P < 0.05), in 7.4 +/- 4.9 mmHg at six months (P < 0.05), and in 6.6 +/- 5.4 mmHg at 12 months (P < 0.05) following iStent implantation. The mean number of hypotensive medications at baseline was 2.9 +/- 0.7 (range 24). Statistically significant reductions in the number of medications of 1.1 +/- 1.1 were observed at three months (P < 0.05), 1.0 +/- 0.7 at six months (P < 0.05), and 1.1 +/- 0.6 at 12 months (P < 0.05). No significant changes in visual acuity were noted. The most common complications comprised mild hyphema in seven eyes and transient IOP = 30 mmHg in three eyes on postoperative day 1. Obstruction of the lumen of the stent with a blood clot was seen in three eyes, and all instances resolved spontaneously. Conclusion: The iStent is a safe and effective treatment option in patients with secondary open-angle glaucoma, and reduces the topical treatment burden in one hypotensive medication.