In a see-through waveguide-based HMD device configured to display holographic virtual images within a field of view (FOV) of the device user, a single pixel or group of pixels are lit to supply illumination at known locations on the display that is reflected from the user's eyes and captured by one or more sensors in an eye tracker. The eye tracker may apply real-time image analysis to the captured reflected light, called “glints,” to extract features of the user's eyes to determine where the HMD device user is looking—the gaze point—and calculate eye movement, location, and orientation. A negative lens functionality utilized in the HMD device to provide a fixed focal depth for the virtual images enables the lit pixels to function as virtual glint sources for the eye tracker sensor that are located at the fixed focal depth and from multiple illumination positions within the user's FOV.