Gel Stent Statistically Noninferior to Trabeculectomy in Glaucoma Treatment

Arsham Sheybani, MD

Courtesy of Washington University School of Medicine

New results from the multicenter, randomized, Gold Standard Pathway Study investigating a gel stent versus trabeculectomy found the gel stent was statistically non-inferior to trabeculectomy in eyes with open-angle glaucoma (OAG).¹

In the analysis, 62.1% of gel stent-treated eyes and 68.2% of trabeculectomy-treated eyes achieved the trial’s primary endpoint of ≥20% IOP reduction at month 12 without an increase in topical IOP-lowering medications, clinical hypotony, vision loss to counting fingers, or secondary glaucoma surgical intervention (SSI).

“At Month 12 following implantation of the gel stent, findings of this study are consistent with those of other recently published prospective studies in which the gel stent was implanted ab interno,” wrote corresponding author Arsham Sheybani, MD, Washington University School of Medicine.

The Gold Standard Pathway Study was the first prospective study to compare the effectiveness and safety of the gel stent compared with those of trabeculectomy, considered the gold standard in glaucoma treatment. It was conducted between October 2018 and May 2021 at 35 centers in the United States, where eligible study participants were randomized 2:1 to the gel stent or trabeculectomy arm at the site level.

Participants were ≥18 years of age and had OAG with an IOP ≥15 mmHg and ≤44 mmHg uncontrolled on current topical IOP-lowering therapy. For the purpose of analysis, investigators assessed IOP at baseline and all postoperative visits. They additionally recorded the use of all topic IOP-lowering medications, best-corrected visual acuity (BCVA), and biomicroscopy findings at all visits.

As IOP-lowering alone may not fully reflect the outcomes of filtering surgery, the primary endpoint was a composite of effectiveness and safety parameters defined as the proportion of patients at month 12 achieving ≥20 IOP reduction from baseline without medication increase, clinical hypotony, vision loss to counting fingers, or SSI in a noninferiority test with 24% margins. Secondary endpoints included mean IOP and medication count over time, postoperative intervention rate, visual recovery, and patient-reported outcomes.

Of 158 eyes enrolled at 30 centers, 139 underwent gel stent implantation (n = 95; 68.3%) or trabeculectomy (n = 44; 31.7%), and 115 of 239 (82.7%) completed the study. Demographics and baseline characteristics were balanced between treatment arms (P ≥ .161).

Upon analysis, the gel stent was statistically non-inferior to trabeculectomy, with a between-treatment difference of –6.1% (95% confidence interval [CI], –22.9% to 10.8%; P = .487). Data showed 62.1% (gel stent) and 68.2% (trabeculectomy) of patients achieved the primary endpoint of ≥20% IOP reduction from baseline.

Regarding secondary endpoints, the mean IOP was 14.4 mmHg on 0.6 medications in the gel stent arm and 11.8 mmHg was 0.5 medications in the trabeculectomy arm. The mean reductions in IOP and topical IOP-lowering medication count from baseline were statistically significant in both treatment arms at all time points (P <.001 for all).

The analysis indicated the between-treated difference in mean IOP reduction from baseline (2.8 mmHg; 95% CI, 0.4 to 5.2) was statistically significant at Month 12 (P = .024), but the between-treatment difference in mean medication reduction from baseline (0.3; 95% CI, –0.0 to 0.7; P = .068) was not.

Sheybani and colleagues also indicated the gel stent resulted in fewer eyes requiring in-office postoperative interventions after excluding laser suture lysis (P = .024), as well as faster visual (P ≤.048), and greater 6-month improvements in visual function problems (P ≤.022). The most common adverse events experienced in the gel stent and trabeculectomy arms were reduced visual acuity (38.9% vs. 54.5%), hypotony (23.2% vs. 50.0%), and IOP increased by ≥10 mmHg from baseline (21.1% vs. 11.4%),

“It is also worth noting that following gel stent implantation, return to baseline visual acuity occurred faster (likely because gel stent implantation was performed without conjunctival dissection), sustained worsening of BCVA was not observed at Month 12, and fewer patients exhibited worsening in BCVA (≥2 lines) at any time during the study, compared with trabeculectomy,” investigators wrote.

References

1. Sheybani A, Vera V, Grover DS, et al. Gel Stent vs Trabeculectomy: The Randomized, Multicenter, Gold Standard Pathway Study (GPS) of Effectiveness and Safety at 12 Months: Gel Stent vs Trabeculectomy: A Prospective Randomized Study [published online ahead of print, 2023 Mar 25]. Am J Ophthalmol. 2023;S0002-9394(23)00134-4. doi:10.1016/j.ajo.2023.03.026