Three-year effectiveness and safety of the XEN gel stent as a solo procedure or in combination with phacoemulsification in open-angle glaucoma: a multicentre study

Abstract

Purpose: To assess the 3-year effectiveness and safety of the XEN gel stent implanted ab interno in open-angle glaucoma (OAG).

Methods: This study was a multicentre, retrospective chart review of consecutive patients with OAG who underwent ab-interno gel stent placement alone or combined with phacoemulsification between 1 January 2014 and 1 October 2015. Outcome measures included mean changes in intraocular pressure (IOP) and IOP-lowering medication count from medicated baseline at 1, 2, 3 (primary outcome) and 4 years (if available) postimplantation. Intraoperative complications, adverse events of special interest (AESIs) and secondary surgical interventions (SSIs) were recorded.

Results: The safety and effectiveness populations included 212 eyes (primary and secondary) and 174 eyes (primary), respectively. Mean IOP and medication decreased from 20.7 mmHg and 2.5 at baseline (n = 163 primary/first implanted eyes) to 13.9 mmHg and 1.1 medications (n = 76) at 3 years postimplantation, respectively. Mean changes from baseline in IOP (-5.6, -6.2 and -6.6 mmHg) and IOP-lowering medication count (-1.8, -1.6 and -1.4) were statistically significant at 1, 2 and 3 years postimplantation, respectively. Results appeared comparable when implantation was performed with (n = 76) or without (n = 98) phacoemulsification. In primary eyes with 4-year IOP and medication count data (n = 27), mean IOP was 14.0 mmHg on 1.3 medications at 4 years postimplantation. Fifteen (7.1%) eyes had intraoperative complications, 31 (14.6%) experienced 46 postoperative AESIs, and 26 (12.3%) required SSI.

Conclusion: The gel stent effectively lowered IOP and IOP-lowering medication count over 3 years, with a predictable and acceptable safety profile, when implanted via the traditional ab-interno technique.

Keywords: MIGS; XEN; gel stent; glaucoma; implant; intraocular pressure.

Fig. 1

Mean and changes in mean IOP and number of IOP‐lowering medications from baseline over time in the total effectiveness.^a OAG population with both IOP measurement and number of topical IOP‐lowering medications recorded at baseline (n = 163^b) (A) and patient subgroup with POAG (n = 120) (B). Mean IOP data are shown with standard deviations. p values were based on paired t‐tests evaluating the difference in IOP or number of topical IOP‐lowering medications from baseline to the indicated postoperative visit; p < 0.05 was considered statistically significant. ^aAll effectiveness analyses included one eye per patient; in cases of bilateral implantation, only the first implanted eye was analysed. ^b11 patients were excluded from analysis of the primary outcome measures as they did not have both IOP and IOP‐lowering medication count data at baseline. IOP = intraocular pressure, meds = medications, phaco = phacoemulsification with intraocular lens replacement, OAG = open‐angle glaucoma, POAG = primary open‐angle glaucoma, SD = standard deviation.

Fig. 2

Proportion of eyes achieving ≥20%, ≥30% and ≥40% IOP reduction from baseline at 1, 2 and 3 years postimplantation of the gel stent in the effectiveness^a OAG population (n = 174^b). ^aAll effectiveness analyses included one eye per patient; in cases of bilateral implantation, only the first implanted eye was analysed. ^bThis analysis included all patients who had IOP data at baseline. IOP = intraocular pressure, OAG = open‐angle glaucoma, phaco = phacoemulsification with intraocular lens placement.

Fig. 3

Scatter plots of IOP reduction as a function of preoperative IOP at 3 years in the effectiveness^a OAG population (n = 174^b) (A) and patient subgroup with POAG (n = 123) (B). Each data point represents one eye. The grey line delineates IOP reduction (lower portion) from IOP increase (upper portion), relative to baseline IOP. Data points below the 20%, 30% and 40% IOP reduction lines achieved that level of IOP lowering or more. ^aAll effectiveness analyses included one eye per patient; in cases of bilateral implantation, only the first implanted eye was analysed. ^bThis analysis included all patients who had IOP data at baseline. ^cIndicates IOP reduction success, as defined in the protocol. IOP = intraocular pressure, OAG = open‐angle glaucoma; POAG = primary open‐angle glaucoma.

Fig. 4

Proportion of eyes achieving IOP ≤18, ≤16 and ≤14 mmHg at 1, 2 and 3 years postimplantation of the gel stent in the effectiveness^a OAG population (n = 174^b). ^aAll effectiveness analyses included one eye per patient; in cases of bilateral implantation, only the first implanted eye was analysed. ^bThis analysis included all patients who had IOP data at baseline. IOP = intraocular pressure, OAG = open‐angle glaucoma, phaco = phacoemulsification with intraocular lens placement.

Fig. 5

Rates of overall, complete and qualified success at 1, 2 and 3 years postimplantation of the gel stent in the effectiveness OAG population (n = 174)^a,b. ^aAll effectiveness analyses included one eye per patient; in cases of bilateral implantation, only the first implanted eye was analysed. ^bThis analysis included all patients who had IOP data at baseline. Overall success was defined as the sum of complete success and qualified success. Complete success was defined as ≥20% IOP reduction from medicated baseline without SSI, clinical hypotony (as defined in the Outcomes section) or topical IOP‐lowering medications, analysed in the effectiveness population. Qualified success was defined as ≥20% IOP reduction from medicated baseline without SSI or clinical hypotony while remaining on the same number or fewer topical IOP‐lowering medications, analysed in the effectiveness population, and did not include eyes that met the criteria for complete success. Eyes that required more topical IOP‐lowering medications at years 1 (implant, n = 3; phaco + implant, n = 1), 2 (implant, n = 3; phaco + implant, n = 1) and 3 (implant, n = 2; phaco + implant, n = 2), compared with baseline, were excluded from the success analyses. IOP = intraocular pressure, OAG = open‐angle glaucoma, phaco = phacoemulsification with intraocular lens placement, SSI = glaucoma‐related secondary surgical intervention.

Fig. 6

Kaplan–Meier curve showing the estimated probability of maintaining overall success at 3 years following gel stent implantation in the effectiveness^a OAG population with both IOP measurement and number of topical IOP‐lowering medications recorded at baseline (n = 163^b) (A) and patient subgroup with POAG (n = 120) (B). Overall success was defined as a primary eye achieving complete success (≥20% IOP reduction from medicated baseline without SSI, clinical hypotony [as defined in the Outcomes section] or topical IOP‐lowering medications) or qualified success (≥20% IOP reduction from medicated baseline without SSI or clinical hypotony, while remaining on the same number or fewer topical IOP‐lowering medications), excluding eyes that required more IOP‐lowering medications postimplantation, compared with baseline. Failing to achieve the overall success at any time during postimplantation follow‐up was considered as failure. Primary eyes were considered as censored in the Kaplan–Meier analysis when their follow‐up period (including completing the study) ended before they failed. ^aAll effectiveness analyses included one eye per patient; in cases of bilateral implantation, only the first implanted eye was analysed. ^bThis analysis was based on the primary outcome measures and thus excluded 11 patients who did not have both IOP and IOP‐lowering medication count data at baseline. IOP = intraocular pressure, OAG = open‐angle glaucoma, phaco = phacoemulsification with intraocular lens placement, POAG = primary open‐angle glaucoma, SSI = glaucoma‐related secondary surgical intervention.