Automated Gonioscopy Assessment of XEN45 Gel Stent Angle Location After Isolated XEN or Combined Phaco-XEN Procedures: Clinical Implications

Abstract

Précis: Angle location of the XEN implant both in isolated and in combined procedures did not appear to influence long-term outcomes. However, more posterior stent placements seem to be associated with increased early postoperative complications. Purpose: The purpose of this study was to assess success and safety outcomes of different levels of insertion of the XEN45 gel stent in the angle in standalone and combined procedures. Methods: This was a cross-sectional study of patients in whom XEN had been implanted without intraoperative gonioscopy. Automated gonioscopy was used for postoperative analysis of the XEN location, classified as anterior or posterior relative to the scleral spur. Absolute success was defined as ≥20% intraocular pressure decrease from baseline and ranging from 6 to 21 mm Hg without medication and qualified success if medicated. The need for additional drainage surgery was considered failure, but needling was allowed. Clinical data were retrieved from patient files. Results: Gonioscopy-assisted XEN location was performed on 42 eyes of 33 patients (14 isolated and 28 combined procedures) on average 18±9 months after surgery. Absolute (32% vs. 35%; P>0.99) and qualified (44% vs. 65%; P=0.22) success was similar in both anterior and posterior placements, respectively. Kaplan-Meier survival analysis yielded similar median survival times for both groups. The distribution of XEN insertion level in the angle was similar in standalone and combined procedures (P=0.75). Although overall safety outcome measures did not differ significantly, the proportion of intraoperative and early postoperative complications was higher in posterior XEN placements (P=0.03). Conclusions: Different locations of XEN45 did not seem to significantly impact late success and safety outcomes, although stents inserted more posteriorly may be associated with a higher rate of early complications. Combined implantation of XEN with phacoemulsification does not seem to influence stent location in the iridocorneal angle in a setting without intraoperative gonioscopy.

Intraocular Pressure and Medication Changes Associated with Xen Gel Stent: A Systematic Review of the Literature

“…Among 58 studies that recorded a minimum of 12 months of follow-up, the postoperative weighted mean IOP was 13.6 mm 4,5,12,15,16,[19][20][21][22]72 In all three groups of studies, the weighted mean average number of postoperative medications was less than 1. The results were similar for a second analysis in which studies were clustered in terciles from lowest mean baseline IOP to highest: First 19 studies (range, 15.3-21.0 mm Hg), 4,10,12,21,22,26,32,35,37,41,[46][47][48]50,54,60,61,65,68 second 20 studies (range, 21.1-23.4 mm Hg), 24,28,30,31,33,34,38,40,[42][43][44][45]53,55,57,58,[62][63]…”

“…5,10,11,15,21,22,29,31,37,40,43,44,50,54,55,58,63,69 In 41 retrospective studies representing 3111 total eyes, a median of 52 eyes (range, 13-242) were followed for a median of 12 months (range, 6-36). 4,12,16,19,20,[24][25][26][27][28]30,[32][33][34][35][36]38,39,41,42,[45][46][47][48][49][51][52][53][56][57][58][59][60][61]…”

“…5,15,16,19,20,25,27,29,36,39,49,51,52,56,59,66,67,70,72 There were 49 studies (n = 3587 eyes) available for an analysis of outcomes by mean baseline age. 4,5,10,11,15,16,[19][20][21][22][24][25][26][27][28][29][30][32][33][34][35][36][37][38][39][40][41][42][43][44]46,47,[49]…”

Recanalization of XEN-45 gel stent occlusion with cortical material after phaco-XEN surgery using Nd: YAG laser treatment

“…Recently, Barao and colleagues reported that placement of the XEN stent in a more posterior location might be associated with increased early complications on an automated gonioscopic study. [ 11 ] In our patient, the approximate length of the XEN gel implant in the anterior chamber was 1.0 mm, and it was placed anteriorly to the scleral spur. We hypothesize that, for the patient in this report, there was enough space between the iris and the stent tip to prevent iris-XEN contact or iris-XEN occlusion in the early postoperative hypotony phase.…”

Moving beyond the Slit-Lamp Gonioscopy: Challenges and Future Opportunities

“…Post-surgical findings were also evaluated by Barão et al who analyzed the location of the XEN stent imaged by GS-1. They found that that different locations of XEN did not seem to significantly impact late success and that combined implantation of XEN with phacoemulsification does not seem to influence stent location [ 28 ]. More recently, Matsuo et al used the GS-1 device to investigate the pattern of peripheral anterior synechia (PAS) formation after ab-interno trabeculotomy and they found that PAS formation rate was significantly higher within the incision compared to other angle sectors.…”