Embodiments of an apparatus comprising a light guide including a proximal end, a distal end, a display positioned near the proximal end, an eye-measurement camera positioned at or near the proximal end to image eye-measurement radiation, a proximal optical element positioned in the light guide near the proximal end and a distal optical element positioned in the light guide near the distal end. The proximal optical element is optically coupled to the display, the eye-measurement camera and the distal optical element and the distal optical element is optically coupled to the proximal optical element, the ambient input region and the input/output region. Other embodiments are disclosed and claimed.