Purpose To determine the relationship between untoward events noted during phacoemulsification surgery associated with aberrant infusion misdirection and their causal relationship to current infusion sleeve design. Setting The New York Eye & Ear Infirmary of Mt. Sinai, New York, New York, USA. Design Retrospective case reports and experimental study. Methods Observations of live cataract surgery were documented with high-definition videography using 3 commercial phacoemulsification platforms. Laboratory studies using a Photron MC2 high-speed camera and the Kitaro cataract surgical system were used to simulate surgical maneuvers and assess flow patterns and visualize the dynamics of fluid movement in the anterior chamber. Color-flow Doppler ultrasound studies were used to demonstrate the effect of infusion fluid on the iris during surgery. Results Misdirected infusion and floppy-iris leaflets were determined to be secondary to a fulcrum effect at the corneal wound that constrained movement of the standard silicone sleeves. The phacoemulsification needles could therefore decenter independently of the infusion sleeve, attenuating infusion volume down 1 side of the sleeve and, as a result, obstructing fluid exiting the ipsilateral port. Conclusions Untoward events associated with aberrant fluid infusion during phacoemulsification surgery were secondary to a fulcrum effect at the corneal wound. Complications included misdirected infusion that facilitated the transport of retained nuclear fragments to the vitreous, inconsistent lens followability during phacoemulsification, and exaggerated movements of the iris particularly consistent with intraoperative floppy-iris syndrome and pseudoexfoliation. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.