Shunting to Subconjunctival Space
Shunting to the subconjunctival space involves the mechanism of diverting aqueous humor to the subconjunctival space from an ab interno stent placed in the angle through a clear corneal incision. The device was created to solve a major problem with tube shunts and trabeculectomy, which is that pressure can reduce, but prevention of hypotony relies on subjective scarring and suture tightness. Shunting to the sub conjunctiva was designed to prevent excessively low pressures and reduce reliance on subjective measures to dictate flow. A bleb is created but it is a more diffuse, low, and less cystic bleb than that with a trabeculectomy. A comfort level with treating blebs post-operatively, such as needling, is required so likely glaucoma specialists and those comfortable with trabeculectomies will find the benefit of this procedure most.
Xen Gel Stent
The Xen gel stent (Allergan) is a soft, permanent, non-migrating, subcon- junctival implant that shunts fluid from the anterior chamber to the subconjunctival space, creating a bleb, much like a trabeculectomy. The Xen stent, however, is implanted ab interno from across the eye through a clear cornea incision. The implant is made of porcine gelatin crosslinked with gluteraldehyde, a material that’s been used for other medical purposes. The cylindrical, 6-mm long implant comes with three di erent-size lumens: 45 μm; 63 μm; and 140 μm.
Watch a video of Zen Gel Stent surgery
Read more about the Zen Gel Stent procedure in an article in Glaucoma Today entitled, “Has a Replacement for Trabeculectomy Finally Arrived?”.