Aqueous Angiography Reveals Discordance with Intraoperative Signs of iStent Outflow

Minimally Invasive Glaucoma Surgeries (MIGS) have documented variable clinical efficacy. To ensure intraoperative functionality of trabecular bypass MIGS, procedures like trypan blue dye stained episcleral venous flow andsigns such as blood reflux in the anterior chamber have been used as surrogate markers for checking functionality of MIGS procedures. Aqueous angiography (AA) images the flow of fluorescent tracer dyes within the aqueous humor outflow channels after intracameral injection of the tracer dye, thus providing confirmatory evidence for the functionality of any trabecular bypass MIGS procedure. Herein, we discuss a novel case comparing the above intraoperative surrogate markers with the confirmatory imaging technique of AA for the functionality of MIGS. A lack of concordance between the two was noted, which provides a word of caution to surgeons using these techniques to ensure functionality of trabecular bypass MIGS. This case indicates the need for further research towards evaluating the validity of these intraoperative surrogate markers for assessing the functionality of trabecular bypass MIGS.