A head-mounted display (HMD) presents content for viewing by users. The HMD includes a display element, an optics block, and a camera. The display element includes content pixels for providing light corresponding to the displayed content and one or more tracking pixels for providing tracking light used for tracking the user's eye movements. The optics block directs light from the display element (light corresponding to the displayed content and that of tracking light) to an exit pupil of the HMD. The camera captures one or images of an eye of the user in response to projecting tracking light on the eye, where the one or more captured images include a distortion of the projected tracking light and are used in determining an orientation of the eye at a time of capturing the one or more images of the eye.