The Episcleral Venous Fluid Wave and Circumferential Extent of Canal-Based Surgery

Blebless canal procedures reduce IOP by increasing flow into the patient’s natural collector system. There is no readily available method of evaluating flow into the aqueous collector channels as performed for external filtration, such as a bleb. The authors previously described the episcleral venous fluid wave (EFW)--a surge of fluid seen in the episcleral veins during phacotrabectome--as a method to determine intraoperative patency of the collector system. The authors demonstrate the EFW and show that it correlates with the extent of angle either cleaved open or stented during canal surgery. The EFW is a new method to visualize patency of the collector system at the time of canal-based surgery and may correlate with reduction in postoperative IOP.