Minimally Invasive Glaucoma Surgeries May Help Manage Intraocular Pressure

Amanda Bicket, MD, MSE

Investigators of a new study assessed the potential of minimally invasive glaucoma surgeries, finding that some techniques may allow patients to manage intraocular pressure (IOP) without the need for medication.

The study was led by Amanda Bicket, MD, MSE, of the University of Michigan, and consisted of data reviews of randomized clinical trials. The team utilized the Cochrane Database of Systematic Reviews, summarizing quantitative data and descriptive analyses from reviews evaluating a variety of minimally invasive surgeries.

They further compared these surgeries with cataract extraction along, other minimally invasive procedures, laser trabeculoplasty, or medical therapy.

As such, their analysis sought “to highlight current evidence for MIGS [minimally invasive glaucoma surgeries] interventions and uncover areas where opportunities for important research remain.”

The Review

In their overview, which included 6 Chochrane reviews published between December 1, 2018 - February 28, 2021, Bicket’s team evaluated the proportion of patients who did not need to use medication to reduce IOP post-surgery.

“Most RCTs included in these reviews reported outcomes according to US Food and Drug Administration guidelines, recording change in IOP from baseline and describing washout of IOP-lowering medications before baseline and postoperative IOP measurements,” they wrote.

The prespecified primary outcomes were analyzed on both a short-term (<6 months), medium-term (6-18 months), as well as long-term (>18 months) basis.

All 6 reviews discussed trabecular bypass with iStent or Hydrus microstents, ab interno trabeculotomy with Trabectome, subconjunctival and supraciliary drainage devices, and endoscopic cyclophotocoagulation.

According to moderate certainty evidence, adding Hydrus as a surgical procedure was considered safe and associated with a greater likelihood of not requiring medication for glaucoma control at medium-term (relative risk [RR], 1.6; 95% CI, 1.4-1.8) and long-term (RR, 1.6; 95% CI, 1.4-1.9) follow-up. 

Additionally, this surgery led to a 2.0 mg Hg (95% CI, −2.7 to −1.3 mm Hg) greater IOP reduction at long-term follow-up compared to cataract surgery alone.

The team also reported that iStent similarly improved medication-free (or drop-free) disease control versus just cataract surgery (RR, 1.4; 95% CI, 1.2 to 1.6). However, this improvement was not maintained through short-term follow-up.

“Addition of a CyPass microstent improved drop-free glaucoma control compared with cataract surgery alone (RR, 1.3; 95% CI, 1.1 to 1.5) but was associated with an increased risk of vraision loss,” they added.

Discussion

Bicket and colleagues thus concluded that Hydrus outperformed the iStent and CyPass in terms safe IOP control.

“Both Hydrus and CyPass, when combined with cataract surgery, conferred a modest but statistically significant mean reduction in IOP over cataract extraction alone (2.0- 2.3 mm Hg)," they indicated. "The evidence for these findings was of moderate to high certainty and network meta-analyses did not strongly favor one device over the other.

Nevertheless, they acknowledged the many gaps that still exist in the evidence base for minimally invasive glaucoma surgeries. These gaps were particularly noticeable for subconjunctival devices, which were not identified in 2 of the included Cochrane reviews.

“Vision researchers and device manufacturers might aid in bridging these gaps with well-designed RCTs reporting effectiveness, safety, and health-related QOL outcomes at 24 months and beyond,” the investigators wrote.

The study, “Minimally Invasive Glaucoma Surgical Techniques for Open-Angle Glaucoma: An Overview of Cochrane Systematic Reviews and Network Meta-analysis,” was published online in JAMA Ophthalmology.