Christoper Go1, Alexandra Klejn2, Nitin Verma1

Purpose: Minimally-invasive glaucoma surgery (MIGS) has been a topic of discussion in glaucoma management for almost two decades. A subgroup of MIGS that is commonly used is implantable MIGS using an ab interno approach including iStent, CyPass, Hydrus and Xen. This study aims to review current literature and compare their effectiveness.
Method: A systematic review is conducted using multiple databases to identify RCTs and non-RCTs from 2008-2018. Inclusion criteria include follow-up period greater than 1 year, patients greater than 18 years of age and less than 15% proportion lost to follow-up. From the identified studies, clinical out- comes were collected including mean IOP, IOP reduc- tion, medication free proportion and adverse events. Result: iStent was investigated most frequently with seven RCTs identified. CyPass and Hydrus were also investigated with large cohort RCTs. Only prospective studies and no RCT were identified for Xen. When comparing the proportion of >20% IOP reduction in the intervention arm (combined cataract
+ MIGS) in the RCTs, iStent achieved 61%, Hydrys 79% and CyPass 77%. In the medication free cate- gory, iStent achieve 71% versus 87% in Hydrus and 85% in CyPass.
Conclusion: Hydrus and CyPass appear to have similar efficacy and are superior to the iStent. How- ever, it is important to note that only one iStent was implanted in the original study whilst the more commonly used iStent Inject encompasses two implants that have been shown to be more effective. As such, superiority cannot be ascertained with cur- rently available evidence and will require further research to be determined.