A novel use of trypan blue during canalicular glaucoma surgery to identify aqueous outflow to episcleral and intrascleral veins

Purpose: We describe a novel technique comprising the use of trypan blue to confirm aqueous outflow to collector channels and aqueous veins after goniotomy with the Kahook Dual Blade (New World Medical, Rancho Cucamonga, CA). Intraocular dyes have been safely used during ophthalmic surgery to evaluate the patency of the trabecular meshwork and collector channels. Further, trypan blue has been safely used to stain the anterior capsule of the lens in cataract surgery, to enhance visualization for capsulorhexis; similarly, trypan blue has been safely used to stain the trabecular meshwork for enhanced visualization during glaucoma angle surgery. Channelography enables evaluation of the collector channels during canaloplasty with fluorescein dye; episcleral fluid wave enables evaluation of the intraoperative structural patency of the conventional outflow system, from the anterior chamber to the episcleral and conjunctival distal collectors after Trabectome goniotomy (NeoMedix Corporation, Tustin, CA). Patients and Methods: We evaluated 4 cases of glaucoma patients who underwent goniotomy with the Kahook Dual Blade to observe whether trypan blue could identify the patency of Schlemm's canal and aqueous egress to episcleral and intrascleral veins. Results: We successfully confirmed the outflow pathway via Schlemm's canal and collector channels with trypan blue in 3 of the 4 cases. Conclusions: We conclude that trypan blue can be used safely to confirm both aqueous outflow and the patency of Schlemm's canal and aqueous veins during canalicular glaucoma surgery.