An aspiration circuit for a fluidics system (11) for selectively controlling aspiration, comprises an aspiration line (52) operatively connected to a surgical instrument (42), an aspiration exhaust line (54) operatively connected to a waste receptacle (58). The aspiration vent line (60) is connected at a first end to the aspiration line； a selectively variable vent valve (62) is operatively connected to the aspiration vent line, wherein the variable vent valve may be selectively moved to selectively change aspiration pressure within the aspiration line. An irrigation line (50) is operatively connected to the surgical instrument (42) and an irrigation pressure sensor is operatively connected to the irrigation line (50). An actuator is connected to the vent valve (62), wherein the irrigation pressure sensor and actuator are connected to a controller (40), which is operative to initiate the actuator to move the vent valve in response to predetermined pressure values detected by the irrigation pressure sensor to vary the aspiration pressure within the aspiration line. The vent valve (62) is a rotary valve that further comprises an input opening (68), an output opening (69) and a channel (66) that connects the input opening to the output opening. The vent valve (62) may be selectively rotated to selectively position the channel (66) in at least partial communication with the aspiration vent line (60).
