Intraluminal deposits: A rare cause of glaucoma drainage implant total obstruction.

Purpose: To report the unforeseen complication of total obstruction of a glaucoma drainage implant (GDI) tube lumen by white deposit material and to present a preliminary report identifying the composition of this material.
Methods: Two subjects with a high IOP due to total obstruction of a GDI tube were reviewed. Both patients had a long history with brinzolamide and timolol maleate eye drops. The GDI tube was swept with a 5-0 polypropylene suture stent in order to open the tube. The intraluminal solid sample was successfully collected from the implant tube in one patient. High-performance liquid chromatography-mass spectrometry (HPLC-MS) was used to determine the origin of the intraluminal sample.
Results: Intraluminal deposits containing components of antiglaucoma drugs e.g., timolol and brinzolamide are a rare cause of total obstruction of GDI tubes.
Conclusions: Our study describes a new cause of total obstruction GDI tubes. The long-term use of timolol maleate and brinzolamide and their presence in the intraluminal solid sample collected from the blocked GDI tube suggest that the glaucoma medication may have a role in the pathogenesis. However, the exact mechanism is unknown and requires further studies.