Anterior Segment Optical Coherence Tomography Signs of Local Dilatation Effect of a Micro-Stent on Schlemm’s Canal

Kevin Gillmann; Giorgio Enrico Bravetti; Kaweh Mansouri; André Mermoud

Kevin Gillmann Glaucoma Research Center, Montchoisi Clinic, Swiss Vision Network, Lausanne
Giorgio Enrico Bravetti Glaucoma Research Center, Montchoisi Clinic, Swiss Vision Network, Lausanne
Kaweh Mansouri 1Glaucoma Research Center, Montchoisi Clinic, Swiss Vision Network, Lausanne, Switzerland
André Mermoud Glaucoma Research Center, Montchoisi Clinic, Swiss Vision Network, Lausanne

Abstract

DOI: https://doi.org/10.3126/nepjoph.v10i2.23030

Introduction: The iStent inject® (Glaukos Corporation, CA, USA) is a relatively new device designed to be implanted ab-interno through the trabecular meshwork. This is, to the best of our knowledge, the first in-vivo description of a trabecular bypass device visualised with anterior segment optical coherence tomography (AS-OCT), and report of its structural effect on Schlemm’s canal.

Case Report: A 74 year-old female patient suffering from long-standing primary open-angle glaucoma and nuclear sclerosis underwent cataract surgery combined with the implantation of two iStent injects®. Surgery was uncomplicated and achieved intraocular pressure (-1 mmHg) and medication (-2 molecules) reduction at 6 months. Under AS-OCT (Spectralis OCT, Heidelberg Engineering AG, Germany) the stent appears as a 300 μm long hyper reflective hollow device within the trabecular meshwork. Approximately a third of it protruded into the anterior chamber. Profound OCT signal loss was notable within the shadow of the device. A second AS-OCT section 500 μm beside the microstent shows a markedly dilated Schlemm’s canal, with a major diameter of 390 μm.

Discussions: This report confirms that AS-OCT is a suitable technique to assess microstent positioning, and provides a first report on the in-vivo appearance of a functioning stent. It also indicates that iStent injects® could have a tangible effect on adjacent portions of Schlemm’s canal with, in this case, a 220% increase in canal diameter compared to the observed average (122 μm). This suggests the IOP-lowering effect of trabecular bypass devices could rely on a dual mechanism involving Schlemm’s canal dilatation.

Keywords: Schlemm’s Canal, Micro-Stent