EyeWorld India June 2017 Issue

60 June 2017 EWAP GLAUCOMA A long-term issue of concern is the potential for peripheral anterior sequelae (PAS). When we create these passageways into the suprachoroidal space, an abrupt closure of the cleft can cause a high spike in IOP. The CyCLE trial showed PAS formation at 10%, 8 the COMPASS trial showed a reduction in PAS formation to 3.1% through a 2-year period. 9 In contrast, if a trabecular stent fails, the pressure tends to return to the patient’s baseline rather than escalate to dangerously high levels. Patient facing decisions Glaucoma is a chronic disease that must be attended for the duration of a patient’s life, and I think that all of these tools have a place in the glaucoma treatment spectrum. As we learn more about these relatively new stents, we may be able to link them directly to specific patient profiles. The trabecular bypass stent restores and maintains that natural physiological outflow and provides a robust benefit profile with minimal downside risk. Furthermore, it opens the door for a titratable therapy. If I use one or two trabecular bypass stents and feel a patient needs additional pressure control, adding a suprachoroidal stent might be my next step. Time will tell if there are patients best served by a suprachoroidal stent as initial therapy. There is a financial misconception out there that these stents are expensive and provide little bang for the buck. If you take the four largest iStent studies and combine them, we see 177 patients with an average reduction of 1.31 medications. That makes the median annual savings from medication reduction about US$720 per patient. In Views from Asia-Pacific Prin ROJANAPONGPUN, MD Associate Professor & Chairman Visanee TANTISEVI, MD Assistant Professor Chulalongkorn University & King Chulalongkorn Memorial Hospital 1873 Rama4 Road, Pathumwan, Bangkok 10330, Thailand Tel. no. +6622564142 Fax no. +6622528290 prinoph@gmail.com, tvisanee@gmail.com F iltering surgery is under attack because of its high rate of complication and unpredictability. MIGS offers better safety profiles, faster recovery, and a simple and more convenient procedure. But this comes with a counterbalance of less IOP lowering efficacy and increased cost. We believe it is justified in less advanced glaucoma cases or when safety and fast recovery is a priority. Different MIGS devices drain aqueous via different channels: trabecular bypass, suprachoroidal space, and subconjunctival space. The iStent and Hydrus microshunts are promising in terms of moderate IOP control with enhanced safety. 1-3 For iStent, more than one implant is suggested by many reports and the placement quadrant must be considered to achieve the target IOP. 4,5 The Hydrus employs the emerging findings of Schlemm’s canal structure and collector channels density. 6 Proper skill and technique will dictate a better outcome. Since the procedure needs good trabecular meshwork visualization and understanding of its structure and function, these implants might not be a good choice in angle closure glaucoma which is still a major problem in East Asia. Notwithstanding, it cannot be exactly stated that it is impossible to do in angle closure eyes as cataract removal can help open the angle to reveal a more accessible trabecular meshwork. We still lack information for whether these microshunts would increase the outflow in the reopened passageway. The suprachoriodal pathway comes into the spotlight because of its voluminous potential drainage space. This may increase efficacy but will compromise safety. A study with gold microshunt implant did not show favorable long-term IOP control. 7 However, over the years, suprachoroidal shunts have been re-innovated, either in terms of material composition or flow design. CyPass and iStent SUPRA are small tubes that can be introduced ab interno. It is performed solely or in combination with cataract surgery. However, the long-term results are limited. Financial concern on these new devices depends on whom they were meant for. Most healthcare system in Asia do not yet support these devices. With the improved MIGS outcome and case selection, we will see more and more MIGS in our practice. Once available, we will need to discuss these options with our patients and get them involved in the decision-making process. References 1. Spiegel D, Wetzel W, Neuhann T, et al. Coexistent primary open-angle glaucoma and cataract: interim analysis of a trabecular micro-bypass stent and concurrent cataract surgery. Eur J Ophthalmol . 2009 May-Jun;19(3):393-9. 2. Arriola-Villalobos P, Martínez-de-la-Casa JM, Díaz-Valle D, et al. Combined iStent trabecular micro-bypass stent implantation and phacoemulsification for coexistent open-angle glaucoma andcataract: a long-term study. Br J Ophthalmol . 2012 May;96(5):645-9. 3. Neuhann TH. Trabecular micro-bypass stent implantation during small incision cataract surgery for open-angle glaucoma or ocular hypertension: Long-term results. J Cataract Refract Surg . 2015; 41:2664–2671. 4. Katz LJ, Erb C, Carcelleretal GA. Prospective, randomized study of one, two, or three trabecular bypass stents in open-angle glaucoma subjects on topical hypotensive medication. Clin Ophthalmol . 2015;9:2313–2320. 5. Malvankar-Mehta MS, Chen YN, Iordanous Y, Wang WW, Costella J, Hutnik CM. iStent as a solo procedure for glaucoma patients: a systematic review and meta-analysis. PLOS ONE . 2015;10(5): ArticleIDe0128146 6. Carreon TA, Edwards G, Wang H, Bhattacharya SK. Segmental outflow of aqueous humor in mouse and human. Exp Eye Res . 2017 May;158:59-66. 7. Skaat A, Sagiv O, Kinori M, Ben Simon GJ, Goldenfeld M, Melamed S. Gold Micro-Shunt Implants Versus Ahmed Glaucoma Valve: Long-term Outcomes of aProspective Randomized Clinical Trial. J Glaucoma . 2016 Feb;25(2):155-61. Editors’ note: Drs. RojanaPongpun and Tantisevi declared no relevant financial interests. MIGS – from page 58 continued on page 63