iSTAT (Intraluminal Suture Transfixed and Titratable) technique for ligature-free Reversal of long-term drainage implant hypotony

PURPOSE: To describe the iSTAT (Intraluminal Suture Transfixed and Titratable) technique, an improvement on prior tube occlusion methods, allowing for variable flow. OBSERVATIONS: A 76-year-old woman who underwent an uncomplicated glaucoma drainage device (GDD) placement for uncontrolled mixed mechanism glaucoma presented with hypotony 4 years post-operatively. The iSTAT technique was performed to adjust the flow in the GDD tube: a 4–0 polypropylene suture tip was blunted with a low-temperature cautery, creating a bulbed end that would occlude the tube. The suture was introduced into the tube bulb-first intracamerally, extending to the plate. If partial occlusion of the tube is desired, the suture can be secured in place by piercing the side wall of the tube tip with the distal end of the suture. After complete occlusion of the GDD tube with a large bulb, the patient had intraocular pressures (IOPs) > 40 mmHg on post-operative day 1, which remained in the 25–30 mmHg range 2–3 weeks post-operatively on maximally tolerated medications. Patient underwent a second revision with a smaller-bulbed stent (with a 3–0 polypropylene suture), which stabilized her IOP at 8 mmHg. CONCLUSION AND IMPORTANCE: The iSTAT technique allows for an ab interno revision, titration of flow, and stabilization of the stent in the wall of the tube. The ab interno approach precludes the need for conjunctival incisions, thus maintaining bleb integrity and permitting surgery under topical anesthesia. The intracameral stabilization of the stent in the tube allows for smaller bulbs to titrate the flow without external ligatures.