1. An eye-imaging system, comprising: a camera system, adapted to capture eye-image light that originates as one or more reflections from an eye of a user, the camera system positioned in a head-worn computer, wherein the head-worn computer is adapted to display digital content to a user along a common optical axis that intersects with an eye of the user such that the user can see the digital content; a light source positioned in the head-worn computer such that it irradiates the eye of the user, along the optical axis, with a pattern of light to produce at least a portion of the reflections from the eye of the user; and a processor adapted to analyze a difference between the irradiated pattern of light and the captured eye-image light, wherein the difference is interpreted as positional changes of the eye of the user.