EyeWorld Asia-Pacific March 2016 Issue

58 EWAP DEVICES March 2016 Views from Asia-Pacific Prin ROJANAPONGPUN, MD Chairman & Associate Professor, Department of Ophthalmology prinoph@gmail.com King Chulalongkorn Memorial Hospital, Chulalongkorn University 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand Tel. no. +662-256-4142 Fax no. +662-252-8290 W hy MIGS? The most pronounced benefit of microinvasive glaucoma surgery (MIGS) is the reduction in complications when compared to trabeculectomy, which is regarded as the gold standard procedure. But this reduction in complications is also counterbalanced by less IOP lowering efficacy, making MIGS seem minimally effective. Such constraints in some MIGS procedures—not all—limit their use in more advanced cases. Instead of being a standalone procedure, most MIGS studies show an additional benefit when combined with the cataract surgery. When to do MIGS? Initial IOP and degree of glaucomatous optic neuropathy dictate the decision making on whether the surgeon performs filtering surgery or MIGS. In a patient in whom cataract surgery is needed, and IOP does not exceed 30 mmHg, phaco/MIGS is effective and worth doing. Various studies—including phaco/trabectome, phaco/iStent, and phaco/Hydrus—have shown that they indeed provide favorable outcomes with the IOP reduction at around 16–30%, even when the initial IOP is as high as 30 mmHg. However, if the patient has advanced optic neuropathy and visual field loss, it is agreed that combined phaco/trabeculectomy or a staged filtering surgery may be a more appropriate option. Phaco/MIGS—which provides more convenience, faster recovery, less trauma and a higher safety margin—is more appropriate for mild to moderate cases. MIGS alone or cataract surgery alone? Given that there is a chance of being drop-free, the MIGS standalone surgical option may be the preferred option in selected patients. Cataract surgery alone should not be promoted as an effective IOP-lowering procedure except in an angle-closure eye in which the lens is identified as the angle- closure mechanism. The future of MIGS: With the improvement in MIGS outcome and case selection, we will see more and more MIGS in our practice. As with any surgery, to decide whether to go for a conventional trabeculectomy, MIGS or combination surgery is to balance the risks/benefits and discuss the options with our patients. Cost will be an issue in many but not all. References 1. Fea AM. Phacoemulsification versus phacoemulsification with micro-bypass stent implantation in primary open-angle glaucoma: randomized double-masked clinical trial. J Cataract Refract Surg . Mar 2010;36(3):407-412. 2. Samuelson TW, Katz LJ, Wells JM, Duh YJ, Giamporcaro JE, Group USiS. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmol . Mar 2011;118(3):459-467. 3. Wellik SR, Dale EA. A review of the iStent((R)) trabecular micro-bypass stent: safety and efficacy. Clin Ophthalmol. 2015;9:677-684. 4. Maeda M, Watanabe M, Ichikawa K. Evaluation of trabectome in open-angle glaucoma. J Glaucoma . Mar 2013;22(3):205-208. 5. Ting JL, Damji KF, Stiles MC, Trabectome Study G. Ab interno trabeculectomy: outcomes in exfoliation versus primary open-angle glaucoma. J Cataract Refract Surg . Feb 2012;38(2):315-323. 6. Pfeiffer N, Garcia-Feijoo J, Martinez-de-la-Casa JM, et al. A Randomized Trial of a Schlemm’s Canal Microstent with Phacoemulsification for Reducing Intraocular Pressure in Open-Angle Glaucoma. Ophthalmol . Jul 2015;122(7):1283-1293. Editors’ note: Drs. Rojanapongpun and Chansangpetch declared no relevant financial interests. Sunee CHANSANGPETCH, MD sunee.ch@chula.ac.th MIGS devices - from page 57