Hydrus microstent for the treatment of primary open-angle glaucoma: overview of its safety and efficacy

ABSTRACT

Introduction

Minimally invasive glaucoma surgeries (MIGS) are now a consolidated reality in many surgical units. The Hydrus Microstent is one of several MIGS devices bypassing trabecular outflow and had excellent results over the years. This article aims to review the key features of the Hydrus Microstent in terms of design, efficacy, and safety.

Areas covered

The present review analyses the main characteristics of the device by evaluating the technical and physical details of its functioning. The evidence that supports a clinical decision summarizes the most influential clinical trials and the most accurate systematic reviews.

Expert opinion

The Hydrus device has been extensively studied regarding biocompatibility and outflow potential. The subsequent clinical studies have been well-built and proved that the device effectively reduces intraocular pressure (IOP) and the eyedrop load. The device covers almost a quarter of Schlemm’s canal circumference, offering at least two advantages: cannulating the Schlemm’s canal provides evidence that the device has been implanted correctly; covering a larger area potentially allows to target multiple collector channels or at least areas of active outflow. This scaffold may prove more effective in naïve patients or subjects who used antiglaucoma eyedrops for a limited period, as the prolonged use of hypotonic medications has been associated with the surgical failure of ab interno microhook trabeculotomy.

KEYWORDS:

• Hydrus Microstent
• glaucoma surgery
• MIGS
• IOP medication
• safety
• primary open-angle glaucoma

Article highlights

• The Hydrus device is made of nitinol, a material with medical applications since 1970. It is a non-luminal open structure with a curvature consistent with Schlemm’s canal (SC), thus providing an intracanalicular scaffold and an alternate route to aqueous humor outflow.

• Biocompatibility studies in rabbit and primate eyes showed no evidence of inflammation, granuloma formation, or metallosis and minimal damage to Schlemm’s canal (SC) endothelium

• Two prospective randomized clinical trials proved that the combined implantation of the Hydrus device with cataract surgery was significantly superior to cataract surgery alone in terms of IOP medication reduction over at least two years.

• A prospective comparative case series proved the superiority of the Hydrus as a solo procedure in terms of medication reduction compared to SLT

• Collectively the Hydrus device has a remarkably high safety profile. It does not seem to determine a significant reduction of the endothelial cell count

• The results of an international real-life registry suggest that the randomized clinical trial Hydrus results are replicable in a real-world scenario

Declaration of interests

AM Fea is a consultant for Ivantis, Glaukos, AbbVie, EyeD, iSTAR, Elios Vision, Santen. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.