EyeWorld India September 2017 Issue

said. “It may be a viable alternative for patients with elevated episcleral venous pressure.” Subconjunctival procedure XEN45 Gel Stent (Allergan, Dublin, Ireland) is a stent made of a soft, collagen-derived gelatin. It is 6 mm long and is approximately the width of a human hair. The stent is injected through a small self-sealing corneal incision using a preloaded IOL-like injector. After being implanted in the eye, it creates a gentle outflow of aqueous from the anterior chamber into the subcon- junctival space. “XEN is a much safer inter- vention for people who might otherwise need a traditional tube surgery,” Dr. Greenwood said. “The data on both the CyPass and the XEN are early but good, so we are learning more as surgeons gain more experience with these de- vices.” Why MIGS? According to Dr. Berdahl, the ideal patient for a MIGS procedure is someone who needs a modest amount of IOP lowering. “Some procedures, like XEN, can get the pressure a little bit lower, but that comes with a trade for a little more risk and a little more postoperative care as opposed to an iStent, which can provide nice IOP lowering with a nice safety profile, but likely not down into the very low double Staining of the trabecular meshwork with trypan blue at the point of the incision in the meshwork. The opening in the meshwork exposes the white posterior wall of Schlemm’s canal. Note the “flaps” of the blue trabecular meshwork. Source: Reay Brown, MD Intraoperative view of an iStent in good position. The remainder of the stent is pointing to the left and is covered by the trabecular meshwork. Source: Michael Greenwood, MD September 2017 EWAP SECONDARY FEATURE 23 Views from Asia-Pacific Manchima MAKORNWATTANA, MD Associate Professor of Ophthalmology, Thammasat University Faculty of Medicine Paholyothin Street, Klong Laung Pathumtani 11120 Thailand Tel. no. +66813767027 manchima123@yahoo.com M IGS procedures have been introduced into glaucoma management for a decade, trying to fill the gap between eyedrops and conventional trabeculectomy—which many surgeons have difficulty dealing with, with several complications such as hypotony, aggressive scar formation, severe intraoperative complications from tremendous changes in IOP, preoperative and intraoperative conditions, and also bleb-related infection or endophthalmitis. Only if a glaucoma surgery has a very high success rate with as few complications as modern cataract surgery would glaucoma treatment shift to glaucoma surgery instead of convincing patients to endure various ocular complications from anti-glaucoma eye drops, for example chronic irritation, ocular hyperemia, prostaglandin-related periorbitopathy (PAP), panda eyes, etc. What bring MIGS to attention are the safety and the earlier intervention than conventional trabeculectomy. However, performing successful MIGS does need angle surgery skills and appropriate and wise patient selection that depend on glaucoma conditions and MIGS working area, the canal, and the suprachoroidal space or the subconjunctival space. In thin, fragile conjunctiva or poor ocular surface patients, subconjunctival space MIGS should be avoided due to future bleb-related complications such as bleb-related endophthalmitis and chronic bleb leakage. For contact lens wearers or swimmers, the non-bleb MIGS, suprachoroidal, and canal surgeries should be considered. However, the non-bleb MIGS provides surgeons with fewer options to manipulate the aqueous drainage postoperatively compared to bleb MIGS, such as needle revision to enhancing the aqueous flow. The other obstacles would be commercial availability, the studies of IOP lowering efficacy, safety and long-term outcomes. Expense and the partial or full reimbursement from insurance are also another surgeon and patients’ concerns. MIGS are recommended in mild to moderate glaucoma. Unfortunately, having financial concerns without any insurance coverage may delay MIGS and prolong exposure to BAK from anti-glaucoma eye drops, which might cause less favorable outcomes due to BAK-related conjunctival tissue fibrosis. On the other hand, performing MIGS in the early stage of glaucoma and in less-BAK exposed eyes may achieve better IOP control. In my opinion, MIGS will take more and more roles in glaucoma care because of its safety, fewer complications, and mild to moderate IOP lowering efficacy. However, conventional trabeculectomy is still an important part of glaucoma care globally in terms of effective pressure reduction and economically friendly surgery. Editors’ note: Dr. Makornwattana declared no relevant financial interests. continued on page 24