Clinical Investigation of New Glaucoma Procedures

Kateki Vinod; Steven J. Gedde


Curr Opin Ophthalmol. 2017;28(2):187-193. 

In This Article


Retrospective case series and nonrandomized prospective studies have provided valuable information about new glaucoma procedures. However, results from these study designs should be interpreted with caution because of the potential influence of selection bias. Randomized clinical trials provide the highest level of evidence for surgical interventions and are critical in our evaluation of the current spectrum of glaucoma procedures. Selection of an appropriate comparator can be challenging. Although the gold standard for glaucoma surgery, trabeculectomy cannot always reasonably be compared to surgeries that do not bypass downstream resistance to flow, as their degree of IOP reduction and complication profiles are expected to be different. Several studies have demonstrated that phacoemulsification can produce substantial and sustained IOP reduction.[7,8] Therefore, surgeries that are commonly combined with phacoemulsification should be compared to phacoemulsification alone, as has been done for iStent, Hydrus Microstent, and CyPass Micro-Stent.

There appears to be an inevitable trade-off between safety and efficacy. Among the procedures discussed, Trabectome, iStent, and Hydrus Microstent appear to be the safest, but at the expense of a modest degree of IOP lowering and reduction in medication burden. The newer subconjunctival, bleb-forming procedures most closely resemble trabeculectomy, and appear to have an expectedly greater ability to lower IOP but higher risk of hypotony than Schlemm's canal-based surgery. Future randomized trials and extended follow-up from published studies are needed to improve our understanding of the long-term efficacy and safety of the newer procedures and to further define their role in clinical practice.