Eyeworld

EW RESIDENTS 60 January 2018 EyeWorld journal club by Swarup Swaminathan, MD, Stephen Moster, MD, Nimesh Patel, MD, Nicolas Yannuzzi, MD, Eric Duerr, MD, Ann Quan, MD, Nathan Scott, MD, MPP Review of "Trabecular micro-bypass stents approach after conventional glaucoma T he surgical options for managing glaucoma have increased exponentially in recent years. Microinvasive glaucoma surgery (MIGS) is a group of procedures characterized by an ab interno approach, minimal trauma to ocular tissue, rapid post- operative recovery, excellent safety profile, and modest efficacy. 1 Cur- rent approaches include increasing trabecular outflow, suprachoroidal shunts, reducing aqueous produc- tion (endocyclophotocoagulation), and subconjunctival filtration. 2 MIGS are considered lower risk procedures than traditional incision- al glaucoma surgeries (i.e., trabe- culectomy and tube shunts), which have significantly higher rates of sight-threatening complications such as suprachoroidal hemorrhage and endophthalmitis. 3 Despite the risk profile, traditional glaucoma surgery is still considered the gold standard in patients with advanced and progressive glaucoma. 4,5 The iStent trabecular micro-by- pass stent (Glaukos, San Clemente, California) was the first trabecular stent approved by the Food and Drug Administration. The iStent is a 1 mm heparin-coated, non- ferromagnetic titanium stent that allows aqueous humor to bypass the trabecular meshwork and drain directly into Schlemm's canal. 6 The iStent Study Group conducted a multicenter randomized clinical trial evaluating the safety and efficacy of iStent placement in combination with phacoemulsification in pa- tients with mild to moderate open angle glaucoma. 7 A greater propor- tion of patients who underwent phacoemulsification with an iStent achieved an unmedicated IOP <21 mm Hg than phacoemulsification alone after 1 year of follow-up. How- ever, a significant reduction in IOP was observed in patients receiving only phacoemulsification. Implan- tation of multiple stents appears to provide additional IOP reduction compared to placement of a single stent. 8 Macher et al. performed a retrospective study evaluating the outcomes of two trabecular mi- cro-bypass stents in patients with uncontrolled open angle glaucoma and previous filtration surgery. The study included patients with prima- ry open angle glaucoma, pseudoex- foliation glaucoma, and pigmentary glaucoma. All patients required additional IOP lowering while using at least two IOP-lowering drops for greater than 6 months after at least one prior filtration surgery. An open angle was required on gonioscopy. The surgical procedure included injecting two iStents utilizing a temporal corneal wound. Of note, the new iStent inject devices (G2-M- IS injector) were utilized, as per the procedure previously described in the literature. 9 In the postoperative period, all patients were placed on topical timolol and pilocarpine for 2 weeks only to prevent synechiae. In this study, 11 eyes (26%) were phakic and underwent concur- rent cataract removal while the re- maining 33 (74%) were pseudopha- kic. At 12 months postoperatively among patients who had only one previous failed filtration surgery, IOP was reduced from 23.8 ± 3.9 to 15.2 ± 2.7 mm Hg. At 12 months among those with multiple prior failed filtration surgeries, IOP decreased from 26.1 ± 5.7 mm Hg to 16.3 ± 3.3. There was also a reduction in the number of medications used, from 2.7 ± 0.9 to 2.0 ± 1.1. Notably, 15 eyes (36%) required a second- ary glaucoma procedure within 6 months after the described interven- tion. The authors utilized an iStent placement grading system to gauge stent positioning, which has not been completed in prior studies and has not been standardized. A total of three eyes (7%) had a post-trabec- ular position of the stent, and only one implant was visible after surgery in two eyes (5%). This study challenges our current approach to the surgical management of glaucoma. MIGS has been generally reserved for early stages of glaucoma, potentially bridging the gap between laser tra- beculoplasty and traditional glauco- ma surgery. Use of MIGS in patients with advanced glaucoma has been limited to date. These devices are being implanted with increasing frequency prior to trabeculectomy, but they have not typically been considered in eyes that have already undergone trabeculectomy surgery with subsequent failure. This study raises the question of whether our standard algorithm for glaucoma surgical treatment should be revised. Bascom Palmer Eye Institute residents Source: Bascom Palmer Eye Institute Steven Gedde, MD, vice chairman of education and residency program director, Bascom Palmer Eye Institute MIGS devices are most commonly used for mild to moderate glauco- ma. I asked the Bascom Palmer residents to review this January JCRS paper on using two iStents for uncontrolled glaucoma. —David F. Chang, MD, EyeWorld journal club editor

• Blank Page
• Blank Page (1)