EyeWorld Asia-Pacific June 2018 issue

Making MIGS – from page 40 June 2018 42 EWAP SECONDARY FEATURE Views from Asia-Pacific Paul HEALEY, B(Med)Sc, MBBS(Hons), MMed, PhD, FRANZCO Eye Associates 187 Macquarie St, Sydney NSW 2000, Australia phealey@glaucoma.net.au Making MIGS Choices: The Asia-Pacific Perspective O ne of the challenges of glaucoma treatment is that not everyone responds in the same way to the same therapy. This makes choices of treatment particularly important. We are fortunate to have more choices in glaucoma therapy than ever before. But how do we choose between medications, laser, and the increasing array of minimally invasive surgical options? Here are a few additional considerations for MIGS in the Asia-Pacific. Glaucoma Severity and IOP goals Our region has enormous variability in glaucoma severity, treatment, and IOP goals. In many countries, patients with very high IOPs, without access to a regular ophthalmic review or even supply of medication progress rapidly to blindness and are usually treated with primary surgery. But without adequate postoperative care, trabeculectomy outcomes can be poor. While we would not normally think MIGS would be efficacious compared to trabeculectomy in these circumstances, the reduced follow-up requirements and greater safety profile may give it an important role. MIGS may also be a particular asset when added to existing cataract surgery outreach programs in areas otherwise without resources. We also have large numbers of people in our region with normal tension glaucoma. In these patients, progression rates are usually slower, but target IOPs are very low. These may be beyond the reach of canalicular stents and only sometimes in reach of supraciliary stents. Filtering stents may still have an important role but like trabeculectomy, require management of wound healing and lifelong vigilance for infection. Angle Closure and Angle Closure Glaucoma The Asia-Pacific is home to most of the world’s angle closure disease and blindness. Some 15% of Chinese eyes have anatomically narrow angles and 15% remain occludable after iridotomy. In this scenario we would expect intraocular MIGS to cause PAS and subsequent failure. While lens extraction may be key, the role of intraocular MIGS in angle closure remains uncertain. “ While there is a general view in high-resource countries that MIGS is a nice adjunct to cataract surgery, its true potential just may be as an inexpensive, cost- effective tool that will change glaucoma around the world. ” –Paul Healey, M(Med)Sc, MBBS(Hons), MMed, PhD, FRANZCO Resources, Availability & Training Lastly but most importantly, the promise of MIGS will remain only a promise without adequate resources, affordable products, and appropriate training. While there is a general view in high-resource countries that MIGS is a nice adjunct to cataract surgery, its true potential just may be as an inexpensive, cost-effective tool that will change glaucoma around the world. If MIGS really is the “cataract surgery” of glaucoma, is it phacoemulsification? Only time, research, and clinical experience will tell. Editors’ note: Prof. Healey is a consultant for Alcon, Allergan, and Glaukos. Chelvin SNG, MD Consultant and Assistant Professor National University Hospital, Singapore 33 St. Thomas Walk, #21-06, Singapore 238113 Tel. no. +6590083991 chelvin@gmail.com M inimally invasive glaucoma surgery (MIGS) has carved out a niche in the glaucoma treatment algorithm, fulfilling a previously unmet need for safer glaucoma surgery that can be offered to patients with less severe disease. 1 The foray of MIGS into Asia was initially tentative but has gathered momentum in recent years. Singapore is at the heart of the MIGS revolution, with the iStent (both iStent Trabecular Bypass Stent and iStent Inject), XEN, InnFocus Microshunt and Hydrus available at certain hospitals, either as a clinical service or through participation in a clinical trial. Asian glaucoma specialists, just like those in the West, are now faced with multiple surgical options for their glaucoma patients, resulting in the paradox of choice. Appropriate patient selection is key to the success of glaucoma surgery, especially MIGS. Even trabeculectomy outcomes can look dire when performed in inappropriate cases, such as in aphakic eyes. In terms of safety and efficacy, not all MIGS devices are created equal. On one end of the spectrum, trabecular bypass devices and procedures have high safety profiles but are modest in their effects, hence are more appropriate for patients with mild-to-moderate glaucoma. 2 On the other end, subconjunctival devices are potentially as effective as trabeculectomy, but can results in more severe complications, such as bleb-related infections. 3 Hence, the MIGS surgeon must weigh the relative importance of safety versus efficacy in each patient and select the most suitable device. Unlike the situation in the United States of America where the use of certain MIGS devices (e.g., the iStent and the Cypass) is restricted to cataract surgery, standalone MIGS is permitted in Asia, allowing pseudophakic patients access to these devices. While most of the clinical data on MIGS is in the context of primary open angle glaucoma, there is great potential for these devices in currently off- label indications, such as primary angle closure glaucoma (PACG). PACG is more prevalent in Asian compared with Caucasian populations, and my preliminary data suggest that XEN implantation is effective in Asian eyes with PACG for up to 18 months. An Allergan-sponsored multicenter study on the XEN implant in PACG is about to commence, and the efficacy of other MIGS devices in PACG eyes should also be investigated. Another subconjunctival MIGS device, the InnFocus Microshunt, is able to achieve intraocular pressure in the low teens. 4 Hence, it is particularly promising in Asia where patients often present with advanced glaucoma. The arrival of MIGS has undeniably enhanced the glaucoma surgical armamentarium in Asia. However, the cost of these devices may be prohibitive in many Asian countries and the cost-effectiveness of MIGS would need to be established. References 1. Sng CC, et al. Microinvasive glaucoma surgery. J Ophthalmol. 2017;2017:9845018. 2. Chen DZ, et al. Safety and efficacy of microinvasive glaucoma surgery. J Ophthalmol. 2017;2017:3182935. 3. Sng CC, et al. XEN-45 collagen implant for the treatment of uveitic glaucoma. Clin Exp Ophthalmol. 2017 Oct 20. [Epub ahead of print] 4. Batlle JF, et al. Three-year follow-up of a novel aqueous humor microshunt. J Glaucoma. 2016;25:e58-65. Editors’ note: Dr. Sng is a consultant for Allergan, Santen, and Alcon, and receives travel support and honoraria from Glaukos.