An HMD device includes a display panel and an x-prism beamsplitter disposed along a first axis between the display panel and an expected position of an eye of a user. The x-prism beamsplitter directs a first light beam in a first direction from the display panel to the eye along the first axis, directs a second light beam in a second direction along a second axis substantially perpendicular to the first axis, and directs a third light beam in the second direction along the second axis, wherein the second light beam is representative of the first light beam and the third light beam is representative of a reflection of the first light beam off of the eye. The HMD device further includes an imaging camera to capture a composite image comprising a combination of both a representation of the second light beam and a representation of the third light beam.