Hydrus Microstent

The Hydrus ® Microstent was approved by the FDA for use in conjunction with cataract surgery for the reduction of intraocular pressure in adult patients with mild-moderate open-angle glaucoma in August 2018. The implant is designed to have adequate structural thickness to support the tissue of the canal while providing maximum open flow areas through the canal, with the proximal portion of the implant exiting the canal through the trabecular meshwork (TM) to allow inflow of aqueous humor from the anterior chamber. {Summary of Safety and Effectivness (SSED)Template (fda.gov)}

3-year outcomes of the HORIZON study comparing cataract surgery (CS) with Hydrus Microstent (Ivantis, Inc) implantation vs CS alone:

• At 3 years, the number of glaucoma medications was 0.4 ± 0.8 in the microstent group and 0.8 ± 1.0 in the CS group (P < 0.001), and 73% of microstent group eyes were medication free compared with 48% in the CS group.{Ahmed IIK, Rhee DJ, Jones J, Singh IP, Radcliffe N, Gazzard G, Samuelson TW, Ong J, Singh K; HORIZON Investigators. Three-Year Findings of the HORIZON Trial: A Schlemm Canal Microstent for Pressure Reduction in Primary Open-Angle Glaucoma and Cataract. Ophthalmology. 2021 Jun;128(6):857-865.}

There was a superior reduction in intraocular pressure and medication use in patients with mild-moderate POAG undergoing cataract surgery and Hydrus microstent implantation vs cataract surgery alone.{Samuelson TW, Chang DF, Marquis R, Flowers B, Lim KS, Ahmed IIK, Jampel HD, Aung T, Crandall AS, Singh K. A Schlemm Canal Microstent for Intraocular Pressure Reduction in Primary Open-Angle Glaucoma and Cataract: The HORIZON Study. Ophthalmology. 2019 Jan;126(1):29-37.}

Intraocular pressure was significantly lower at 2 years in the Hydrus plus cataract surgery group compared with the cataract surgery alone group, with no differences in safety in patients with open-angle glaucoma.{Pfeiffer N, Garcia-Feijoo J, Martinez-de-la-Casa JM, Larrosa JM, Fea A, Lemij H, Gandolfi S, Schwenn O, Lorenz K, Samuelson TW. A Randomized Trial of a Schlemm’s Canal Microstent with Phacoemulsification for Reducing Intraocular Pressure in Open-Angle Glaucoma. Ophthalmology. 2015 Jul;122(7):1283-93.}

Based on data synthesized in Cochrane reviews, randomized clinical trial data associate the Hydrus with greater drop-free glaucoma control and IOP lowering than the iStent; however, these effect sizes were small.{Bicket AK, Le JT, Azuara-Blanco A, Gazzard G, Wormald R, Bunce C, Hu K, Jayaram H, King A, Otárola F, Nikita E, Shah A, Stead R, Tóth M, Li T. Minimally Invasive Glaucoma Surgical Techniques for Open-Angle Glaucoma: An Overview of Cochrane Systematic Reviews and Network Meta-analysis. JAMA Ophthalmol. 2021 Sep 1;139(9):983-989.}

The Hydrus had a greater rate of complete surgical success and reduced medication use compared to 2 istent at 1 year{Ahmed IIK, Fea A, Au L, Ang RE, Harasymowycz P, Jampel HD, Samuelson TW, Chang DF, Rhee DJ. A Prospective Randomized Trial Comparing Hydrus and iStent Microinvasive Glaucoma Surgery Implants for Standalone Treatment of Open-Angle Glaucoma: The COMPARE Study. Ophthalmology. 2020 Jan;127(1):52-61.}

Both Hydrus and SLT decreased IOP in patients with uncontrolled Primary open angle glaucoma, with Hydrus having significant reduction in medication dependence as well.{Fea AM, Ahmed II, Lavia C, Mittica P, Consolandi G, Motolese I, Pignata G, Motolese E, Rolle T, Frezzotti P. Hydrus microstent compared to selective laser trabeculoplasty in primary open angle glaucoma: one year results. Clin Exp Ophthalmol. 2017 Mar;45(2):120-127.}