Apparatuses, systems, and methods are provided for rapid venting of vacuum to mitigate occlusion break surge within a phaco fluidics aspiration system. The aspiration system may utilize a positive displacement pump to generate flow and a vent valve to vent or moderate the pressure or vacuum level based on pressure sensor feedback detected within the eye and at the pump. Embodiments described herein provide a quick-opening vent valve that produces a quick-opening flow response upon angular rotation of the quick-opening vent valve. The flow performance at the quick-opening vent valve is improved by increasing the effective cross-sectional area of the valve at near-closed valve positions. In particular, the increase in the cross-sectional area is achieved by forming a concaving edge portion to complement a circular edge of and opening of a flow channel formed through the vent valve.