Abstract: A head-mounted device may have left-eye and right-eye optical modules, each of which includes a lens barrel/support, a gaze tracker in the lens barrel, a display coupled to the lens barrel, and a plurality of lenses in the lens barrel that provide an image from the display to a corresponding eye box. The gaze tracker may include light emitters mounted on a printed circuit and light detectors. Each of the lenses may include a peripheral edge that defines a footprint that entirely overlaps a footprint of the printed circuit. The display may be mounted in a display bezel, and the display bezel may include recesses in which the light emitters are mounted. The recesses may be chamfered to increase the signal-to-noise ratio (SNR) of the gaze tracker. Alternatively or additionally, a lens and/or a reflector may overlap the light emitters to increase the SNR of the gaze tracker.