What are Trabecular Bypass Implants?
Trabecular bypass implants are tubes that work by shunting aqueous fluid from the anterior chamber through the sclera into the subconjunctival space. The EX-PRESS® Glaucoma Filtration Device would fit within this definition. Because they shunt fluid into the subconjunctival space a bleb is produced. The use of antimetabolites such as Mitomycin-C (MMC) or 5-FU may be necessary in order to maintain the bleb.
Is this beginning to sound like a modified trabeculectomy? If so, it’s because trabecular bypass implants are essentially attempts to achieve the same outcome as trabeculectomy but with better control over the rate of fluid flow out of the eye. In theory this should result in fewer unwanted complications such as early and chronic hypotony. It also means that all of the unwanted long-term complications related to bleb formation and antimetabolite use are still possible.
Types of Trabecular Bypass Implants
There are three trabecular bypass implants that have received the European CE mark and/or are in clinical trials as of the time of this writing:
- InnFocus MicroShunt®
- Rheon Medical eyeWatch™
- XEN Gel Stent