36-Month Outcomes of Standalone Kahook Dual Blade Goniotomy Compared with Ab-Interno Closed Conjunctiva Xen Gel Stent Implantation

Abstract

Purpose: To compare the safety and effectiveness of standalone Kahook Dual Blade (KDB) excisional goniotomy to standalone ab-interno Xen gel stent implantation in eyes with moderate-to-severe open-angle glaucoma (OAG).

Methods: A single-center, retrospective study including eyes with moderate-to-severe OAG undergoing standalone KDB goniotomy or Xen gel stent implantation was conducted. Intraocular pressure (IOP), the number of antiglaucoma medications taken daily, and best-corrected visual acuity (BCVA) were recorded at baseline and for up to 36-months. Primary outcomes assessed included changes from baseline in IOP and the number of antiglaucoma medications taken. Intergroup comparisons were conducted using independent-samples Student's t-tests. The incidence of intraoperative and postoperative adverse events and the need for glaucoma surgical re-interventions were also recorded.

Results: Eyes receiving standalone KDB (n=26) or Xen gel stent (n=45) surgery were analyzed. The baseline mean IOP and number of antiglaucoma medications in both groups were as follows: KDB: 23.2 ± 6.0 mmHg, 2.2 ± 1.4 medications; Xen: 22.7 ± 8.8 mmHg, 3.0 ± 1.0 medications. At 36 months, IOP was reduced to 16.6 ± 5.4 mmHg in KDB eyes (n=23, -23.5%; p=0.0004) and 15.3 ± 5.6 mmHg in Xen gel stent eyes (n=15, -22.1%; p=0.006), while number of antiglaucoma medications was reduced to 1.1 ± 0.7 (-30.8%; p=0.0005) and 2.2 ± 1.4 (-25.6%; p=0.01), respectively. Three eyes (11.5%) in the KDB group and 19 eyes (42.2%) in the Xen gel stent group required additional surgery before month 36 due to refractory high IOP.

Conclusion: Both KDB goniotomy and Xen gel stent implantation significantly lowered the IOP and antiglaucoma medication burden in patients with moderate-to-severe OAG. While the Xen gel stent is frequently used to treat moderate-to-severe OAG patients with uncontrolled IOP, standalone KDB goniotomy may be equally effective as a long-term intervention, reducing the need for subsequent glaucoma surgery.

Keywords: kahook dual blade; micro-invasive glaucoma surgery; open angle glaucoma; xen gel stent.

Figure 1

Mean IOP (in mmHg) at baseline and all time points for KDB goniotomy and Xen gel stent implantation groups. N values at baseline, 1 month, 3 month, 6 months, 12 months, 24 and 36 months were 26, 26, 23, 22, 24, 18, and 23 in the KDB group and 45, 44, 42, 34, 25, 21and 15 in Xen Gel Microstent group. Error bars indicate standard deviation.

Figure 2

Kaplan-Meier cumulative probability of failure for Kahook Dual Blade goniotomy and Xen gel stent implant. There was significant difference between both groups (log-rank p= 0.008).

Figure 3

Mean medication use at baseline and all time points for KDB goniotomy and Xen gel stent implantation groups. N values at baseline, 1 month, 3 month, 6 months, 12 months, 24 and 36 months were 26, 26, 23, 22, 24, 18, and 23 in the KDB group and 45, 44, 42, 34, 25, 21and 15 in Xen Gel Microstent group. Error bars indicate standard deviation.