Gel Stent Implantation—Recommendations for Preoperative Assessment, Surgical Technique, and Postoperative Management

Abstract

The surgical management of glaucoma offers the potential to lower intraocular pressure (IOP) independent of patients’ compliance with their medication regimen. Procedures such as trabeculectomy and tube shunt placement often yield large magnitudes of IOP reduction, but may be associated with short- and long-term complications. Microinvasive glaucoma surgery (MIGS) offers an alternative surgical approach that is inherently less invasive; however, most devices that fit in this category are associated with a lesser degree of IOP-lowering efficacy compared with traditional glaucoma surgeries. A newer MIGS device, a gel stent that facilitates drainage to the subconjunctival space, appears to offer similar IOP reduction to trabeculectomy, but with much less tissue manipulation; better predictability; and less sight-threatening complications, thus making it a potentially safer and more predictable surgical option in appropriate patients. The following proposed protocol, based on evidence-based practices and augmented where necessary by the opinions of experienced surgeons, provides guidance for the pre-, intra-, and postoperative management of patients receiving a gel stent implant. The goal of this protocol is to provide a framework for better patient selection and preparation, surgical pearls, and how best to assess and manage patients in the postoperative period.

Two-year results of a multicenter study of the ab interno gelatin implant in medically uncontrolled primary open-angle glaucoma

“…In line with the increasing trend of subconjunctival injection of MMC in trabeculectomy, all eyes implanted in this study received subconjunctival antifibrotic injection (range: 10-80 μg for MMC; two patients received 500-μg 5-FU) to allow precise dosing, compared with the traditional sponge method [44,45]. The study thus adds to the prospective data on the perioperative administration of MMC by subconjunctival injection with implantation of the gelatin stent, at dosages aligned with expert recommendations (10-40 μg) [46].…”

“…Potential study limitations include some variability in the perioperative regimens, which may have impacted the study outcomes. Current recommendations from surgeons experienced with the gelatin stent suggest that preoperative preparation of the conjunctiva and ocular surface, placement closer to the 12 o'clock position, avoiding penetration of Schlemm's canal during implantation, making sure that the implant is free and mobile under the conjunctiva at the end of surgery, and achieving specific target IOP on day 1 or a low week-1 delta IOP, among others, may help optimize outcomes; most, however, were not published and thus not implemented during this study [46]. At the time of initiation of this study, the gelatin stent was very new on the market and no best practices were established, so the study results also reflect the investigators' learning curve with the surgery [46] and the variation in preand postoperative regimens associated with typical clinical settings.…”

“…Current recommendations from surgeons experienced with the gelatin stent suggest that preoperative preparation of the conjunctiva and ocular surface, placement closer to the 12 o'clock position, avoiding penetration of Schlemm's canal during implantation, making sure that the implant is free and mobile under the conjunctiva at the end of surgery, and achieving specific target IOP on day 1 or a low week-1 delta IOP, among others, may help optimize outcomes; most, however, were not published and thus not implemented during this study [46]. At the time of initiation of this study, the gelatin stent was very new on the market and no best practices were established, so the study results also reflect the investigators' learning curve with the surgery [46] and the variation in preand postoperative regimens associated with typical clinical settings. Another potential limitation is the fact that < 5% of the study population was of Asian and Black/African ethnicity mITT, modified intent-to-treat; phaco, phacoemulsification with intraocular lens placement a Among study eyes that underwent needling at any time point IOP, intraocular pressure; mITT, modified intent-to-treat; phaco, phacoemulsification with intraocular lens placement; SD, standard deviation a Based on the number of eyes with data available at baseline and the indicated visit [48][49][50].…”

Technique of Xen Implant Revision Surgery and the Surgical Outcomes: A Retrospective Interventional Case Series

“…It is important to consider how to approach Xen implants following the initial surgery to understand when it may be appropriate to perform revision surgery and in which patients it is indicated. In their article, Vera et al [15] provide an excellent flow chart on the management of high IOP post Xen implantation which is largely based on bleb morphology. We agree that in situations where there is no or minimal bleb it is vital to perform gonioscopy to identify lumen occlusion, which can be then treated with YAG laser.…”

“…At this stage, if the bleb remains flat we would proceed to surgical revision to ensure the correct position and function of the implant. Vera et al also [15] describe the option of revision at this stage, but they do not document the details of the surgical technique and the likelihood of success.…”