A device, such as a head-mounted device (HMD), may include a frame and a plurality of mirrors coupled to an interior portion of the frame. An imaging device may be coupled to the frame at a position to capture images of an eye of the wearer reflected from the mirrors. The HMD may also include a mirror angle adjustment device to adjust an angle of one or more of the mirrors relative to the imaging device so that the mirror(s) reflect the eye of the wearer to the imaging device.