Abstract
Purpose :
To assess the clinical outcomes and bleb morphology following sub-tenon’s surgical implantation of the XEN Gel Stent.
Methods :
A retrospective review of 17 eyes of 17 patients after sub-tenon’s (open) XEN Gel implantation. The clinical outcomes noted were intraocular pressure (IOP) and number of anti-glaucoma medications at 1, 3 and 6 months post-operatively. Bleb morphology was studied by utilizing the anterior segment feature of the Triton Swept-Source Optical Coherence Tomography (OCT). The bleb characteristics noted were: bleb wall thickness, internal height, and degree of internal reflectivity, which was classified as low (1), medium (2), high (3) according to the colour scale on AS-OCT. The bleb morphology was further characterized as uniform (1), sub-conjuctival separation (2), microcytic multiform (3) and multiple internal layer (4).
Results :
Mean pre-operative IOP was 28.59+8.57mmHg on 3.53+1.01 anti-glaucoma medications. A statistically significant reduction in IOP was noted at postoperative months 3 and 6 with a mean IOP reduction of 13.24+4.25mmHg and 15.0+6.89mmHg (n=14), respectively.
At most recent follow-up, mean IOP was 14.65 + 5.96mmHg, representing a 45% overall decrease in IOP. In functional blebs (n=15), AS-OCT showed a bleb wall thickness of 103.33+31.29µm, bleb height of 542.6+126.297 µm with the presence of a posterior episcleral fluid (PEF) lake of 389.73+277.02 µm. 87% of functional blebs showed a medium (2) internal reflectivity along with medium-high bleb wall reflectivity. Most of the blebs were characterized as having multiple internal layers (40%). While both early (< 12 months) and late blebs (>12 months) were found to have medium internal reflectivity (91% and 75% respectively), the bleb wall thickness was noted to have lower reflectivity (50%) in late blebs as compared to medium-high (100%) in early blebs.
Conclusions :
The sub-tenon’s (open) technique of XEN Gel implantation has been noted to provide significant IOP control with a low rate of post-operative bleb needling. This study helps characterize the bleb appearance and morphology and begins to help us understand the bleb changes with time so that we can better manage the postoperative course following implantation of these devices. Sub-tenon’s placement of Xen Gel implant allows for good IOP control, and AS-OCT imaging can provide useful information regarding bleb appearance and morphology.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.