The initial sketches of the concept the lens with the sensor monitoring pupil dilation and reporting information to a physio, however if a player is unwillingly to wear a scrum-cap why would he wear a lens?

I moved away from the lens and towards a thin piece of tape strapped on the brow with cameras to monitor the pupil dilation.

Potential idea for the responsibility moving to the ref.

A couple of models testing if the camera would have view of the pupil, using light to verify. In this angle it doesn't view enough of the pupil.

Slight change of the angle views a lot more of the pupil

attempt from below.