An eye tracking system comprises a structured light emitter, a camera assembly, and a controller. The structured light emitter illuminates a portion of an eye of a user with a dense structured light pattern. The dense structured light pattern produces a distorted illumination pattern on the portion of the eye. The camera assembly captures one or more images of the distorted illumination pattern that is associated with the portion of the eye. The controller estimates a position of the eye based on the captured one or more images and a model of the eye. The eye tracking system may be part of a head-mounted display.