Katz and associates present an interim report of a prospective randomized study of one, two or three trabecular micro-bypass stents as a stand-alone procedure in patients with open-angle glaucoma. A total of 119 patients (38 with one stent, 41 with two stents, and 40 with three stents) were enrolled at one clinical facility in Armenia and followed for 18 months. Mean unmedicated IOP at 18 months was 15.9 ± 0.9 mmHg in the one-stent group, 14.1 ± 1.0 mmHg in the two-stent group, and 12.2 ± 1.1 mmHg in the threestent group. Unmedicated IOP ≤ 18 mmHg at one year was achieved by 89.2%, 90.2%, and 92.1% in the one-stent, two-stent, and three-stent groups, respectively. Unmedicated IOP ? 15 mmHg was seen in 64.9%, 85.4%, and 92.1% of the respective groups. No intraoperative ocular adverse events occurred, but specific data about postoperative complications was not provided. The authors only indicate that no patients experienced complications or adverse events commonly associated with conventional glaucoma procedures.
Most previous studies of the trabecular micro-bypass stent have evaluated the procedure in combination with phacoemulsification cataract extraction. The present study investigated stent implantation alone, thus allowing a determination of the IOP-lowering effect of the stent without the confounding influence of cataract surgery. Furthermore, the measurement of IOP at the annual visit after a medication washout period provides a clearer assessment of the efficacy of stent placement. The current study further establishes the benefit of the trabecular micro-bypass stent in reducing IOP, and also demonstrates an incremental enhancement of efficacy with use of multiple stents.
Cost is an important consideration not factored into the study design. Health insurances will generally only reimburse one stent. Additionally, the U.S. Food and Drug Administration approved the trabecular micro-bypass stent in adult patients with mild to moderate open-angle glaucoma in conjunction with cataract extraction, but not as a stand-alone procedure. The authors have acknowledged some weaknesses of their study. It enrolled a homogeneous population of Caucasian patients, involved a single site, did not mask investigators, and had only one baseline IOP measurement. Despite these limitations, the authors are to be congratulated for contributing an important study on the efficacy of the trabecular micro-bypass stent.