Ophthalmic surgical devices, systems, and methods for automatically controlling the injection or extraction of viscous fluids from a patient's eye are provided. A syringe pump connected with an actuation line and a powered syringe provides pressures for viscous fluid injection or extraction in a vitreous chamber of the eye. A sensor disposed adjacent to or inside the eye determines sensor data relating to an intraocular pressure (IOP). The controller receives the sensor data and regulates the injection or extraction of the viscous fluid in response to the detected IOP, such as by controlling the syringe pump. The controller may determine whether the IOP is above an upper threshold or below a lower threshold and may control the syringe pump to regulate the injection or extraction of viscous fluid to maintain the IOP between the upper and the lower thresholds.