Subconjunctival filtration procedures
The XEN Gel stent (Allergan), also approved by the FDA in 2016, and the investigational InnFocus Microshunt Glaucoma Drainage System (InnFocus), lower IOP by creating a pathway for aqueous humor outflow to the subconjunctival space. The XEN Gel stent represents the third generation of the device. Featuring a 45-µm lumen, its design provides good IOP lowering while protecting against hypotony.
With follow-up to 1 year after implantation of the current XEN Gel stent, IOP was reduced by 40% and medication burden by 85%. Data from 3 years of follow-up with earlier iterations of the device show sustained efficacy.
The procedure for implanting the XEN Gel stent is a sutureless procedure that involves a needle stick. Mitomycin-C is used, and a bleb is created, but it is an ab interno procedure, where the filtration bleb is lower lying and less avascular than the blebs created with ab externo procedures, such as trabeculectomy or the ExPress Glaucoma Filtration Device (Alcon Laboratories), Dr. Vold said.
“Up to 25% of the blebs following the XEN implant procedure require needling, but my sense is that as we gain experience, we can potentially reduce the needling rate to 5% to 10%,” he added.