EyeWorld Asia-Pacific June 2017 Issue

62 June 2017 EWAP GLAUCOMA Clemente, California) in 62 eyes of 43 patients with primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma, ocular hypertension, or secondary/post-traumatic glaucoma, the 3-year outcomes showed a sustained reduction in IOP, from mean preoperative of 24.1 mmHg to a mean of 14.9 mmHg at 36 months, and an excellent safety profile. 1 The mean pressure reduction of 8.5 mmHg outdid the mean reduction of 4.1 mmHg observed after a 3-year follow-up period in the Ocular Hypertension Treatment Study (OHTS), which examined the effect of topical ocular hypotensive medication in POAG patients, who had a mean preoperative IOP of 23.9 mmHg. 2 Another prospective pilot study involved implantation of two trabecular micro-bypass stents in 39 open-angle glaucoma patients, achieving a significant and sustained reduction in IOP and medication over 18 months of follow up. 3 The mean unmedicated IOP decreased from 25.3 mmHg preoperatively to 17.1 mmHg at 13 months. In a published review on the iStent, the authors show the safety and efficacy of the iStent system based on the outcomes of randomized controlled clinical trials, revealing IOP reductions of 8–27% and medication reductions from 80–100%. 4 Dr. Jünemann elucidated that other MIGS devices like the iStent, Hydrus (Ivantis Inc., Irvine, California), Cypass (Alcon, Fort Worth, Texas), and AqueSys XEN gel stent (Allergan, Dublin, Ireland) showed promise but were not as well-documented through clinical trials. One investigation in open- angle glaucoma patients presenting with IOP values from 22–38 mmHg revealed a mean postoperative IOP of 15 mmHg without medications using the iStent, 5 while the Hydrus achieved at least 20% IOP reduction in 80% of the 100 study eyes with open- angle glaucoma at 24 months after combined cataract plus Hydrus implantation surgery. 6 Initial clinical experience with the Cypass micro-stent showed a mean reduction in IOP of 9.6 mmHg and reduced medications in a study that combined the Cypass with cataract surgery in 167 eyes. 7 Finally, cataract surgery combined with the implantation of the XEN gel stent resulted in a postoperative reduction in IOP of below 18 mmHg in 85% of 37 eyes with open-angle glaucoma. 8 “These MIGS devices each take advantage of different drainage options within the aqueous drainage meshwork. The iStent is a trabecular stent that reduces transtrabecular resistance. The Hydrus is a Schlemm’s canal microstent, while the Cypass uses the suprachoroidal drainage system to shunt aqueous, increasing uveoscleral outflow. The XEN gel stent, however, comes close to traditional filtration surgery Views from Asia-Pacific Ivan GOLDBERG, AM, MBBS, FRANZCO, FRACS Clinical Associate Professor, University of Sydney Floor 4, 187 Macquarie Street, Sydney NSW 2000, Australia Tel. no. +61-2-9247-9972 Fax no. +61-2-9232-3086 eyegoldberg@gmail.com T wo principles need to guide glaucoma management: optimal long- term visual outcomes for patients as individuals and maximization of therapeutic strategic choices at every step along the treatment pathway. The latter principle allows us as clinicians to work with each patient to decide on a management strategy based on likely benefits, taking possible complications into account. Like in a game of chess, possible complications include what future choices might be enabled, or worse, curtailed by any choice made today. For example, choosing to insert a glaucoma drainage device like an Ahmed or a Baerveldt curtails future options for a trabeculectomy. Warmly welcomed therefore is the profusion of loosely named “MIGS” procedures, offering various ways of lowering intraocular pressure (IOP) by very different pathways. They have burst onto the clinical scene in a bewildering array: trabecular by-pass stents, ab interno canalicular patency expansion, supraciliary drains and ab interno bleb-forming stents. Each has supportive evidence, of varying strength and for varying lengths of follow-up. Remember the adage “the curse of glaucoma management is long-term follow-up”. Inevitably, some MIGS approaches, failing to meet needs in the long-term, will join a long historical list of ideas that seemed good at the time, but failed to cut the mustard. Others will prove useful, especially following anticipated improvements. With the dizzying array of MIGS procedures increasingly available, we need to determine which one(s) work best for which patients, for which types of glaucoma, and at what stages in the progressive glaucoma process. To be successful long- term, each device will need to find its niche. As techniques for insertion and perioperative management vary widely between them, one of our major challenges will be to master the necessary skills, to avoid using only one MIGS device as it is the only one we might know how to use safely and effectively. Ironically, with their more modest IOP-lowering efficacy compared with traditional glaucoma drainage surgeries, MIGS devices have burst onto the scene when evidence is strong that ambitious IOP target levels offer better visual preservation. That is why trabeculectomy remains the gold standard: it is the only approach likely to yield single digit IOPs. Being able to perform a high-quality, well-managed trabeculectomy as well as a glaucoma drainage device remain core competencies for ophthalmologists offering a comprehensive glaucoma service, as well as keeping up to date on the emerging long-term results from the many MIGS procedures increasingly on offer. Editors’ note: Dr. Goldberg declared having no relevant financial interests. Trabeculectomy – from page 61