Outcomes Comparison Between Baerveldt 350 and Ahmed ClearPath 250 Tube Shunts for the Treatment of Glaucoma

Tube shunt implantation is a common type of surgery considered standard of care for treating significant potentially-blinding glaucoma where medical and laser treatment, and previous surgeries, have failed to control intra-ocular pressure (IOP) sufficiently to stop glaucoma progression towards blindness.

Since a larger plate tube (e.g., Baerveldt 350) is more difficult to implant requiring longer surgical time and intraoperative ocular muscle manipulation with possible patient discomfort, a smaller plate tube shunt (e.g., Ahmed ClearPath 250) requiring shorter surgical time and no ocular muscle manipulation may have an advantage if the long term surgical outcomes were the same.

However, the literature is lacking regarding the effect of the tube plate size on the final outcomes of tube shunt implantation. Most published comparisons are between totally different types of tube shunts regardless of plate size, often made of different materials, often comparing valved vs. non-valved tube shunts,combining different plate sizes in the same study groups,5 mixing tubes with or without combined cataract surgery in the same study groups, or comparing surgeries performed by several surgeons utilizing different surgical methods. Further, all these studies utilize tubes implanted into the anterior chamber (AC) thus increasing the risk of corneal failure, with no comparisons at all between tube shunts implanted through the ciliary sulcus of the eye designed to reduce the risk of corneal failure. Our Principle Investigator (AW) is specializing and well-published in this type of tube shunt implantation.

This prospective randomized trial is designed to resolve all these confusing factors in the literature and finally provide the answer of whether tube plate size has an effect on the final outcomes of tube shunt implantation by performing a "clean" study that would isolate the effect of tube plate size on long term outcomes. To achieve this goal our study will utilize two non-valved tube shunts with a different plate size (350 vs. 250 mm2) made of identical materials, in eyes that have already had cataract surgery, and all performed by the same surgeon (AW) through the ciliary sulcus.