An ophthalmic surgical system (100, 200), comprising: a surgical microscope operable to provide a field of view of a surgical site to a user; a display device (126, 128, 222) in communication with the surgical microscope, the display device operable to output a graphical overlay into the field of view of the surgical microscope; a tool configured to be inserted into a patient and operable to perform a surgical task associated with the surgical site while the user visualizes the field of view using the surgical microscope; a computing device operable to: generate a control signal (312, 414, 316, 318, 320) to adjust one or more configurable parameters of the tool in the response to user input; and output the control signal (312, 414, 316, 318, 320) to the tool to control the tool according to the user input; and an input device operable to receive the user input from the user to adjust the one or more configurable parameters associated with the tool; wherein the computing device comprises a graphical overlay module including computer-executable instructions for generating the graphical overlay in the field of view; characterized in that: the graphical overlay includes fields (405, 407) for displaying, selecting and modifying the one or more configurable parameters, such that the user input is entered using the fields (405, 407) while the user visualizes the field of view using the surgical microscope; and the computing device is further configured to display in the field of view an activation field to manually activate or deactivate the graphical overlay in response to a user selection of the activation field. a surgical microscope operable to provide a field of view of a surgical site to a user; a display device (126, 128, 222) in communication with the surgical microscope, the display device operable to output a graphical overlay into the field of view of the surgical microscope; a tool configured to be inserted into a patient and operable to perform a surgical task associated with the surgical site while the user visualizes the field of view using the surgical microscope; a computing device operable to: generate a control signal (312, 414, 316, 318, 320) to adjust one or more configurable parameters of the tool in the response to user input; and output the control signal (312, 414, 316, 318, 320) to the tool to control the tool according to the user input; and generate a control signal (312, 414, 316, 318, 320) to adjust one or more configurable parameters of the tool in the response to user input; and output the control signal (312, 414, 316, 318, 320) to the tool to control the tool according to the user input; and an input device operable to receive the user input from the user to adjust the one or more configurable parameters associated with the tool; wherein the computing device comprises a graphical overlay module including computer-executable instructions for generating the graphical overlay in the field of view; characterized in that: the graphical overlay includes fields (405, 407) for displaying, selecting and modifying the one or more configurable parameters, such that the user input is entered using the fields (405, 407) while the user visualizes the field of view using the surgical microscope; and the computing device is further configured to display in the field of view an activation field to manually activate or deactivate the graphical overlay in response to a user selection of the activation field. the graphical overlay includes fields (405, 407) for displaying, selecting and modifying the one or more configurable parameters, such that the user input is entered using the fields (405, 407) while the user visualizes the field of view using the surgical microscope; and the computing device is further configured to display in the field of view an activation field to manually activate or deactivate the graphical overlay in response to a user selection of the activation field.