Example systems, devices, media, and methods are described for controlling virtual elements or graphical elements on a display in response to hand gestures detected by an eyewear device that is capturing frames of video data with its camera system. An image processing system detects a series of hand shapes in the video data and determines whether it matches a predefined series of hand gestures. Each predefined series of hand gestures is associated with an action. The system controls movement of the virtual element, relative to the display, in accordance with the associated action. In an example hand shape that includes a thumb sliding along an extended finger, the system establishes a finger scale along the extended finger, calibrates a graphical scale with the finger scale, and controls movement of an interactive graphical element, such as a slider, according to the current thumb position relative to the calibrated graphical scale.