EyeWorld Asia-Pacific December 2018 Issue

Trabecular outflow options by Rich Daly EyeWorld Contributing Writer AT A GLANCE • FDA-approved stents have undergone clinical trials that demonstrate their ef cacy. • Among options, stenting of the trabecular meshwork is seen as straightforward and the most widely learned approach. • A fundamental question on the canal remains whether to open one area, a few areas, or the whole canal for maximum IOP reduction. Surgeons address the growing number of trabecular outflow options and their preferences T he growing number of trabecular outflow surgi- cal options require careful consideration. The iStent (Glaukos, San Cle- mente, California), a trabecular bypass device instilled at the time of cataract surgery through a clear corneal incision, was FDA approved in 2012 and followed by the iStent inject, which received FDA approv- al in June 2018. The latter device allows for the implantation of two devices, noted Dana Wallace, MD , glaucoma specialist, Thomas Eye Group. Another stent is the Hydrus (Ivantis, Irvine, California), which uses a clear corneal incision at the time of cataract surgery and serves as a stent and scaffold for several clock hours of Schlemm’s canal. That device has not yet received FDA approval but may in the near future, said Nathan Radcliffe, MD , assistant professor of ophthal- mology, Icahn School of Medicine at Mount Sinai, New York. Beyond stents, surgeons have a number of different ways to ad- dress the trabecular meshwork, in- cluding two trabecular procedures that remove or expand parts of the canal without a stent. Both the Trabectome (Ne- oMedix, Tustin, California) and Kahook Dual Blade (New World Medical, Rancho Cucamonga, California) are performed through a clear corneal incision, unroof the trabecular meshwork, and can perform trabeculotomy for several clock hours. Another trabecular outflow op- tion is gonioscopy-assisted trans- luminal trabeculotomy (GATT), which can be performed through a clear corneal incision and uses an ab interno approach with either a suture or the iTrack microcatheter (Ellex, Adelaide, Australia) to per- form 360 trabeculotomy. “If performed with the iTrack microcatheter, viscodilation can be performed concurrently, which can improve outflow through Schlemm’s canal,” Dr. Wallace said. “It can be done independently of cataract surgery.” Approaches to canaloplasty include use of the iTrack micro- catheter, the Visco360 device (Sight Sciences, Menlo Park, California), which can perform a 360 ab in- terno canaloplasty, and the Omni Combined Procedure System (Sight Sciences), which uses an ab interno approach to perform both 360-de- gree viscodilation of Schlemm’s canal and a 360-degree trabecul- otomy. Choice matters Surgeons’ choices among the op- tions should be considered for safety and efficacy. Dr. Radcliffe noted that FDA- approved stents have 1 or 2 years of clinical trials that demonstrate their efficacy with prospective studies of hundreds of patients. Trabecular procedures have less efficacy and safety data—usually a retrospective or prospective single- armed series of data. The advan- tage of such procedures is that they use established CPT codes, can be performed on any stage of glau- coma, and can be used on patients with any type of insurance. Stents are more limited for both indica- tion and insurance. Clinical considerations should include the way the interventions are used. “In terms of efficacy, the more places you can either stent open or bypass the trabecular meshwork completely will lead to greater efficacy,” Dr. Wallace said. “How- ever, unroofing of the trabecular meshwork for a significant number of clock hours does increase the risk of bleeding.” For that reason, such proce- dures may not be the best choice for patients who are on anticoagu- “ It makes sense that the practitioner who is also treating glaucoma patients would want to be using both stents and the procedures to best tailor options to a patient, taking into account the cataract status, health insurance, and disease state. ” - Nathan Radcliffe, MD continued on page 34 September 2017 EWAP SECONDARY FEATURE 33 Dec 8