Presented at the: 2020 Annual Meeting and Exhibition of the Canadian Ophthalmological Society (COS) in Vancouver, BC, Canada (ePoster) and at the University of Toronto Department of Ophthalmology & Vision Sciences (DOVS) 62nd Annual Research day.
Purpose: Micro-invasive glaucoma surgery (MIGS) is a less traumatic and potentially safer surgical method for patients with open-angle glaucoma. However, it is a recent development for which the high-quality literature must be evaluated.
Study design: Systematic review
Methods: A review of MIGS was conducted by searching Ovid MEDLINE, EMBASE, and Cochrane CENTRAL (2006 to 2019). The primary efficacy indicators were reductions in intraocular pressure (IOP) and topical medication use postoperatively. Adverse event analysis was conducted; risk of bias assessment was performed using the Cochrane, Newcastle-Ottawa, and World Glaucoma Association recommendations.
Results: From 10076 articles identified, 3476 baseline eyes across 20 trials met all eligibility criteria and were included. The mean age was 69.5 ± 2.9, 53.7% were female, 77.4% were Caucasian, and 80% of included studies were randomized controlled trials. One study had last follow-up at less than one year, fifteen studies had follow-up extending 1-2 years, and four had longer than two years of follow-up. MIGS procedures or devices assessed included ab interno canaloplasty (ABiC), cyclophotocoagulation (CPC), CyPass® Micro-Stent, excimer laser trabeculotomy (ELT), Hydrus® Microstent, iStent® (1st generation), iStent® inject (2nd generaton), Kahook Dual Blade®, micropulse (MDLT), Trabectome®, and XEN® Gel Stent. A pattern of more significant IOP and medication reduction was observed in patients who received a MIGS device relative to control intervention. Across all studies at last follow-up, the mean IOP reduction was 8.0 ± 2.2 mmHg (n = 2067; range: 2.4–16.5 mmHg) vs. 7.1 ± 3.3 mmHg (n = 1234; range: 1.7–16 mmHg) and the mean reduction of topical medications was 1.4 ± 0.4 (n = 1864; range: -0.2–3 mmHg) vs. 1.0 ± 0.7 (n = 1234; range: -1–3 mmHg) in MIGS vs. control eyes, respectively. The 1st generation iStent had the most literature supporting its efficacy, followed by the Hydrus. Adverse events were more common among phaco-only eyes (42.3%) vs. standalone-MIGS eyes (21.9%); the rate was 45.0% for phaco-MIGS eyes. The most common adverse events following MIGS implantation included stent obstruction, inflammation, and repeat surgical intervention.
Conclusions: Overall, there is some evidence to support the role of trabecular bypass and suprachoroidal MIGS devices in the treatment armamentarium for glaucoma. MIGS can effectively reduce IOP, decrease the number of topical medications taken, and minimize the number of complications associated with more invasive surgical devices, thus improving quality of life. We await the upcoming RCT evidence from other MIGS devices including the XEN® Gel Stent and InnFocus MicroShunt and hope through this iterative process to elucidate the comparative efficacy, safety, and future role of MIGS in the glaucoma surgical paradigm.
Keywords: MIGS, ocular drainage implant, glaucoma surgery, filtration surgery, open-angle glaucoma, IOP reduction
Studies Included in Analysis: