Devices, systems, and methods for treatment of an eye alter aspiration flow from the eye in response to an occlusion of the aspiration conduit pathway. Where aspiration is drawn from the eye using a volumetric pump, the pump can be reversed so as to induce fluid reflux from the aspiration conduit pathway into the eye to help clear the occlusion. The pump may vary the reverse flow in response to sensed aspiration pressure or the like, and the reverse flow may be halted before the pressure within the aspiration conduit pathway adjacent the eye significantly exceeds the irrigation fluid pressure and/or the pressure within the eye. Reflux may alternatively be generated by modulating a vent valve disposed between an irrigation conduit pathway and the aspiration conduit pathway.