Schlemm's Bidirectional Fluid Wave and Luminal Blood Reflux as Novel Intra-Operative Signs Confirming Optimal Placement of the iStent.

Purpose: Trabecular micro-bypass devices (TBDs) such as the iStent series (Glaukos Corporation, Laguna Hills, CA), are effective in reducing intraocular pressure (IOP). However, precise placement of TBDs is crucial in achieving surgical efficacy, as device malpositioning may lead to suboptimal IOP reduction. We demonstrate two novel intra-operative signs to aid confirmation of accurate iStent placement, without reliance on imaging technologies.

Methods: Surgical technique report with video accompaniment.

Surgical technique: Two intra-operative clinical signs which confirm optimal iStent placement are described: (1) Luminal Blood Reflux - achieved by gently decompressing the anterior chamber, with or without flushing of the stent lumen with balanced salt solution (BSS), thereby confirming stent positioning in the Schlemm's Canal (SC). (2) Schlemm's Bidirectional Fluid Wave (SBFW) - observable when flushing with BSS, suggesting fluid movement in the canal segments adjacent to the iStent device, thereby confirming stent patency and positioning in the SC.

Conclusion: The identified signs are useful, feasible and reproducible indicators of accurate iStent placement. Future studies may evaluate the application of these confirmatory manoeuvres in diverse clinical contexts and further establish correlation with clinical outcomes.